Jun 092013
 

There must be something in the air at the moment; I was recently expounding the virtues of delaying a horse’s training under the saddle only to come across an article last week on The Horse website talking about (race)horse performance at 2, 3 and 5 years related to lesions.

The cause was at that moment of little interest, the age of the horses was. Should we be riding at such immature ages?

Despite being worlds apart, the racehorse industry and the home-hack do have one main thing in common, the wish to turn their beautiful horse into a beautiful rideable horse as soon as possible. After all, most of us don’t just want to look at our horse…

There is plenty of motivation to start early too. In dressage, there is a minimum age at which a horse may compete; according to FEI regulations for international dressage competition, it is six years but for many national events, the rules are different with the minimum age being as low as three. And when one considers horse-racing, the ages are even lower – the racing of two-year-olds is quite commonplace which requires them to be saddled up for the first time when they are not much older than 1½.

For the professional trainer and owner, it is all a question of money. Often the horse is – or can become – quite valuable. Keeping a horse costs money (ironically, for the owners of such horses, it is often just a fraction of their earnings) and the natural desire is to see the horse earn its keep as soon as possible. And eventually, a racehorse can be put out to stud and earn yet more that way – these days not even needing to attain a respectable age with the ability to freeze sperm – but the health of the horse is never the greatest consideration.

So what about the mere mortals of this world? Most horse owners will agree that a horse should not be ridden until it is about 4 years old. A respectable age, one could say; the horse is obviously no longer a foal and is more likely to grow outwards than upwards. However, the growth plates are still a long way off being closed. The last plates will close somewhere between 5½ and eight years old – and it is specifically these growth plates that are found in the back of the horse – all 32 of them!

Most growth plates lie across the weight bearing plane – think of knees, ankles, shoulders etc. – and are less affected by the carriage of weight. But the growth plates in the back lie parallel to the weight bearing plane whereby the back is easily streched and thus can suffer under the weight of the rider.

skeleton of the horseTo clarify, this is the order and the approximate age at which the growth plates close up:

1. Birth: distal phalanx (coffin bone)

2. Birth and six months: middle phalanx

3. Between six months and 1 year: proximal phalanx

4. Between 8 months and 1½ years: metacarpals/metatarsals (cannon bones)

5. Between 1½ and 2½ years: carpal bones

6. Between 2 and 2½ years: radius-ulna

7. Between 2½ and 3 years: ulna/femur, section that carries weight above the radius; tibia

8. Between 3 and 3½ years: humerus; bottom part of the femur

9. Between 3 and 4 years: pelvis begins to close, beginning with the extremities of the ischium, ilium and sacrum

10. Between 3½ and 4 years: lower part (that carries weight) of the scapula (shoulderblade)

; top neck vertebrae

12. From 4 years: tarsal bones then the growth plates between fibula and tibia (not without reason that 18th century literature forbade ploughing, crossing of deep mud and jumping for young horses)

13. Between 5½ and 8 years: vertebrae (the larger the horse and the longer the neck, the longer it takes for the growth plates to close up. For stallions, add another six months: this means a “warmblood” horse of about 17hh will not be fully grown until 8 years old.)

Of course, all this does not mean that we cannot do anything with our horses until they are eight, but it should certainly set us thinking about our training schemes.

For the professional horseworld, time is loss – except the economics are not taken into account. Maybe not so interesting for the racehorse owner – his horse is often little more than a money factory – but certainly for the livery and riding school owners. In much of Europe, the average age of a riding school horse is horrifically low and the general life-expectancy shows no correlation with what a horse should (healthily) be able to reach. Based upon the size of the animal and the size and rate of its heart etc., the horse has a potential life-expectancy of 50 years. Realistically a little lower at around 40 to 43 years. But a horrific number of horses has already been written off by the age of 20 – imagine writing off people when they get to 38 or 40…

Take a look at the table below – and decide for yourself which of the two columns fits your way of thinking best:

Begin training3 years7 years
Full potential7 years10 years
End “useful” life18 years35 years
Total work period15 years?25 years

Just by delaying the moment we start to ride by just 3 years, we can win 10 years in “useful” life. It makes you think…

 

Growth plate information: Timing and rate of skeletal maturation in horses, Dr Deb Bennett, 2005
“Useful Life” table: based on observations by Pierre Enoff, bio-mechanical engineer
Original article published in Dutch: http://www.kobolt.nl/gezondheid/leeftijd-bij-inrijden/   https://sabots-libres.eu/site/engagement/2013/leeftijd-bij-inrijden/

Jun 072013
 

O-Master in proper collectionProper collection is the most efficient way for a horse to carry itself (and also to move). A horse can only collect itself. We cannot force a horse into collection.

Only after I have started my internship at Taonara (Belgium), have I learned what proper collection really means and how it woks scientifically. I also learned the concept of contra collection (by the courtesy of Josepha Guillaum – see article Collection (1)) and finally understood why I always felt like I could not collect the school horses (nor any other horse I ever rode), until now.

I feel that it is time to share my new insights with my readers.

In order to fully understand what I mean with the concept of collection, it is important that you read both parts of the article collection. And please, feel free to comment. I am curious in what you have to say on this topic!

Let me start this article in the same was as I have started the former article Collection (1): Concept and Contra Concept, by trying to define collection.

Definitions of collection:

Wikipedia defines collection as “when a horse carries more weight on his hind legs than on his front legs”. As I have Weight-bearingalready explained in the former article, this understanding of collection is simply wrong. The horse carries around 55% of his weight on the forehand (neck and head), and approximately 45% by the hindquarters. But, these numbers of weight-bearing change constantly, depending on what the horse is doing. When it rests, with the head lowered towards the ground, and one hind leg cocked up, there is more weight on the forehand. However, when it flees there is more weight shifted towards the hind-end (100% weight bearing on the hind legs is achieved when the horse rears). In the picture on the right side, you can actually really see how much weight is one the horse’s forehand (nicely underlined/brought out by the “rider” leaning forwards as well).

Another definition I found was stated in the article Definition Collect, Collection by K. Blocksdorf. This definition states that collection is

When a horse can carry more of its weight on its hindquarters than on the forelegs when ridden or driven. His back will be raised as he engages his stomach muscles. He will be flexing at the poll and will carry himself lightly. This makes the impulsion that comes from the hindquarters much greater (…). The horse can be more easily maneuvered and can carry a rider with greater ease. The horse will reach further underneath its body with its hind legs making stops and turns much more precise.

Overall, I must say that I like this definition a lot, except for the beginning, since it reminds me of the Wikipedia definition. To me, it has many of the most important elements mentioned in collection. Just compare the bullet points below on collection with this definition, and you will find that there actually are a lot of overlaps.

Why do we want collection?

Proper collection is necessary for the horse to carry itself as well as the rider in the most efficient way. Horses are not made for carrying around riders on their back. They must be trained to do so, in order to not break down or get injuries from that. A rider doesn’t only put some extra weight on the horse, but also ads pressure. The horse tries to avoid this pressure by hollowing its back and tense the back muscles (very bad for the horse! And again contra collection!). Another thing that happens when a rider goes on the horse, is that the horse’s balance is disturbed; for a flight animal this can have sever (fatal) consequences. So, before we can even think of collection, we must first teach the horse to stay relaxed, and then to raise his back, and only then can we really start working on proper collection.

Branderup on a properly collected horse

Furthermore, collection is necessary to get the horse to use its body properly, especially when we ask the horse to do something unnatural, i.e. carrying around a rider on his back. Often, the horse hallows its back and tends to fall on his forehand. From this, many injuries can result, especially relating to the back, the head and neck, as ell as the forehand.

Unfortunately, horses are most often not trained in a proper manner and will carry the rider wrong and are usually even taught to perform in contra collection (and even Rollkur). Have you never wondered why there are so many crippled horses coming out of the professional riding disciplines?

So, all things considered, proper collection helps the horse to carry itself and us properly, insures safty of horse and rider, improves any type/discipline of riding, and is a necessity for maintining a healthy horse.

this YouTube video shows a nice way of a high form of collection with the rider

What is proper collection?

Proper collection can be observed most often when the horse runs around freely in the field. Collection occurs (in the wild) when the horse feels in danger, intimidates rivals, fight, flight, imponieren (marries or opponents), and when playing around.

Proper collection has to do with energy, the ego and balance of a horse.

  • In collection, the energy of the horse is collected. When you look at a horse in proper collection (especially the Spanish breeds), than you can really see the energy contained in a horse. In Spanish bull fights for example one can see a lot of truly collected horses full of nearly overflowing energy! One of the most important (pre)conditions for collection related to energy, is impulsion, which can basically be described as energy coming from the hindquarters (moving the horse forward). Impulsion leads to the engagement of the hindquarters. The hind legs are brought deeper underneath the body and for the rider it feels like riding “uphill” instead of “down-hill”.
  • It is important to notice that a horse can only collect itself. We cannot force a horse to collect itself. We can only aid, but we cannot enforce. In order for a horse to want to collect itself, it must feel good about itself – the ego must be pushed (by us) and we will get a horse that wants to present itself to us. In my internship, I have firstly been really introduced to horses that truely feel good about themselves and that love to collect! It is amazing. So, in order to be able to achieve collection, the horse needs strength, flexibility, balance and proprioception, and not to forget, self-confidence and the desire to do so. So it’s not all about pumping muscles, it’s also about the nervous system, comfort and motivation.
  • Collection also has a lot to do with balance. In order for a horse to be collected, it must foremost be balanced – with or without a rider. For a horse it is of necessity to be balanced at all times, otheriwse a predator might have an easy dinner, for the horse cannot run away properly.

In this YouTube video, all of the aspects mentioned above, and the bulletin points underneath can be observed!

Bulletin Points

I have also tried to note down some of the most important things happening in collection:

  • Higher erection of the neck

  • Vertebral column arches upward

  • Collection au natural

    Flexion at the poll

  • Vertical head position

  • Withers come upwards

  • Free and light shoulders

  • Usage of “stomach muscles”/abs

  • Ribcage is lifted up

  • Usage of upper line neck and back muscle (nuchal ligament is contracted)

  • Longissimus dorsi can move freely

  • Get the back up

  • Collection au natural

    The pelvis tilts

  • Engagement of the hindquarters

  • Setting the hind legs under – Stepping in under the body

  • Shorter, higher strides

  • Lowering of the hind leg joints

  • Freely moving tail

  • “Shorter body”

It is important to note that all of these things are interconnected and interrelated. This is due to the horse (bio)mechanics.

More detailed explanations

In this section, I will briefly elaborate on some of the bulletin points mentioned above and try to make the connections between them clear.

  • The joints – hip, knee, hock and pastern – are always bent to a degree, which leads to shock-absorbing movements. This bend affects the forehand as well, since, due to the bending of the joints in the hindquarters, the croup is slightly lowered, which in turns arches the spine slightly upward and thus raises the forehand. This increased flexion of the joints during the weight bearing phase, is a prerequisite for impulsion. (See above – energy/impulsion). The forehand of a horse should not be forgotten though, since it is pushed up by the muscles of the shoulder the chest and also somewhat the neck muscles.
  • A horse uses his abs to support the arch of the back and the croup.
  • The base of the neck is lifted and the upperline muscles are contracted. The nose drops towards the vertical
  • The tail of the horse should be slightly arched (neither tucked in, nor overtly sticking out) in a horizontal line and then fall down freely, moving gently from side to side.

Levade, the highest form of collection

Levade, with rider

Conclusion

I would like to end my article with a quote by the old (horse) master Xenophon:

If one induces the horse to assume that carriage which it would adopt of its own accord when displaying its beauty, then, one directs the horse to appear joyous and magnificent, proud and remarkable for having been ridden.

Finally, one of the nicest videos on collection I have seen so far:

References:

http://horsemanpro.com/articles/collection.htm

http://en.wikipedia.org/wiki/Collection_(horse)

http://www.equusite.com/articles/riding/ridingCollection.shtml (read this article for a bio-mechanic explanation!)

http://www.equusite.com/articles/riding/ridingCollection.shtml

http://www.josepha.info/ (article contra collection)

http://www.pferdemeldungen.de/2011/10/hin-und-weg-von-der-losgelassenheit_1853.html

http://todayshorse.com/what-is-collection/

http://horses.about.com/od/glossaryofhorsetermsc/g/collection.htm

Pictures:

Youtube.com

http://www.youtube.com/user/TaonaraTV#p/u/3/IbHXw7Sj8K4 (Taonara – O-Master)

http://www.youtube.com/watch?v=NDJPDfwidVc&feature=related

http://www.youtube.com/watch?v=aMB0QTDbNjU&feature=related

http://www.youtube.com/watch?v=mAWjTnFqVvA&feature=related

 

Originally published on Stéphanie Kniest’s blog Homo Equus: http://lilith16.wordpress.com/2011/11/15/collection-2-proper-collection/

Jun 072013
 

I believe that one of the most important things to pay attention to when training horses is proper collection.  This concept is probably the most misunderstood concept among a large number of (professional) riders. When I turn on the TV and watch a dressage show, or go into a barn and watch people riding, what I encounter most often is a wrong form of collection  and/or not even an attempt to collect the horse at all. Thus, in either case no collection whatsoever.

 

Definitions of collection

The first thing one usually does when trying to find out about a certain subject is googeling it and usually ending up at Wikipedia. Wikipedia claims that collection is “ when a horse carries more weight on his hind legs than on his front legs” (Wikipedia.com). This statement, even though it is heard most commonly when we talk about collection, is not correct! The horse cannot carry more weight on the forehand than on the hind legs, because in the front of a horse are the neck and the head located. I think that this mistaken statement has arisen due to the fact that it might look like the horse carries less weight on the forehand. This happens because the front legs of the horse are raised, while the pelvis of the horse tilts down (see section proper collection for a more detailed explanation). Another definition works out better: “Collection is the bringing together of both ends of the horse for the purpose of lifting and lightening the forehand”(TodayHorse.com). In this definition, one of the main goals of proper collection, the lightening of the forehand, is brought forward, without implying anything about physical weight being carried on the forehand.

Contra-Collection

Before I will explain what proper collection is (in my next post – the article got really long all of the sudden when I was writing it, so I had to divide it in two posts), I will first introduce the opposite: contra collection. This term has been introduced by a dear friend of mine Josepha Guillaume. Much of my understanding of contra collection (and collection in general) is actually derived from her cliniques and her horses (all of them teaching me a lot). By understanding what contra-collection is (and how it comes about), I feel that one can more easily understand and even better value true collection. To make the connection more clear in the text, the contra-collection aspects are written in bold letters, while the opposite aspects of proper collcetion are written in italics.

Our fault

In my opinion, contra collection has to do with how a horse is being ridden. I believe that it is only because of us that a horse will ever walk in contra collection.Young, untrained horses for example mainly walk in their natural, horizontal balanceContra collection happens when the horse is ridden from “front to back” instead of from “back to front”, or in other words, when the horse pulls himself forward with the forehand (rather than pushing himself with the hindquarters).

Our fault of emplyoing aids

Often some form of “aids”, such as draw reins, running martingales, or tiedowns are applied to force the horse’s neck down. The problem is that all of these so called “aids” strengthen those very muscles that raise the horse’s head and drop the base of his neck. Thus, the horse ends up being even more high-headed and more restive with tighter back and loins muscles, than before.

What exactly happens when we tie a horse down?

  • By pulling the horse’s head down, we distort the balance system of the horse (which, just like in humans, is located between the ears). The horse actually feels like it will fall over; in order to prevent this from happening, it tries to pull its head up again (the lower neck muscle is contracted(rather than the topline neck muscle). This also leads to a contracted back muscle (raher than a relaxed back muscle), which disturbs the horse’smovement and leads to unrhtymic gaits (rather than a rhtymic gait). Furthermore, it starts to fall on his forehand in order to not fall on his nose (muscles are contracted) (rather than a light forehand).
  • By employing a strong hand or aids, the horse is forced into specific frame, which will produce, among other things, a shortened and stiff stride(rather than bent properly the joints of his legs), in which the horse’sshoulders aren’t raised.Furthermore, the hind legs will come out behind the horse and the front legs will be set more underneath the horse (rather than having the hind legs deeper underneath the body). Also, the back of the horse drops down (rather than being raised upward).
  • Also, the horse will probably flex his neck at the centerline (rather than at the poll), which leads the horizontal/straight line to rotate downward in the front (rather than rotate upward). The horse will carry the weight on the forehand with the longissimus dorsi, the shoulders, the lower neck muscles and the front legs. A horse that has been rideen in such manner has a very specific composition: the lower neck buldges outward, there is an unnatural bend on the topline of the neck(extreme S shape), the shoulders are heavily developed while there islittle muscle on the hind legs nor on the topline of the neck, the withers are tugged in and the longissuímus dorsi is so tense that the horse cannot maintain proper rhytem in the gaits.

For a better understanding

I was reading through my article and I feel that it might be helpful to introduce a movie that explains the horse’s anatomy. So, here we go:

Movie 1

Movie 2 (is a video of images on the horse’s anatomy – like you would find in a book)

If you know any other helpful movies, please feel free to comment and introduce those =)

It is always useful when exploring the concept of collection to deepen one’s knoweldge in the horse anatomy. Just buy a book on horse anatomy (for example Gerd Heuschmann – If horses could speak)

Examples

I would like to briefly introduce two examples. in the first example I will explain what happens when the horse’s neck is forced down, while the second example very briefly explains what happens if the horse’s neck is forced too much upward.

If the horizontal line falls to the front (the bit is underneath the hip line) and the horse is asked (usually with spurs) to engage his hind legs by placing them well underneath the body, than the horse’s back will be pressured upward, leaving the hind legs lightened (total opposite of the proper collection). This will also result in the horse’s energy to be waste by him trying the reach the ground and lose balance.

Another example, opposite of lowering the head, is erecting the head. In this case, the horse doesn’t adequately bend his joints in the hind legs and the back becomes pressured downwards.

In neither one example can proper collection be achieved.

Effects of contra collection

–> All in all, what happens is thus the exact opposite of collection, hence the name: contra-collection.

Horses that have been ridden in contra collection for a long time have all the opposite muscles of proper collection well developed and trained. Thus, it is a long way to restore and built up the riight muscles for proper collection (but usually possible)

Also, this form of contra collection will, in the end, lead to pain and injuries of the horse (especially the neck and the forehands, as well as the back). Examples are sore stifles, sore back, kissing spine syndrome, lameness, and all sorts of front end problems.

Click here to check out some really good pictures that help you understand the problematical parts.

_

…to be continued…

References:

http://horsemanpro.com/articles/collection.htm

http://en.wikipedia.org/wiki/Collection_(horse)

http://www.equusite.com/articles/riding/ridingCollection.shtml (read this article for a bio-mechanic explanation!)

http://www.equusite.com/articles/riding/ridingCollection.shtml

http://www.josepha.info/ (article contra collection)

http://www.pferdemeldungen.de/2011/10/hin-und-weg-von-der-losgelassenheit_1853.html

http://todayshorse.com/what-is-collection/

Bilder:

YouTube.com

(1) http://www.youtube.com/watch?v=47SHPAe0s0k

(2) http://www.youtube.com/watch?v=fITBkQOFuBo&feature=related

 

Originally published on Stéphanie Kniest’s blog Homo Equus: http://lilith16.wordpress.com/2011/11/15/collection-1-concept-and-contra-concept/

Jul 012012
 

Welcome to my round up of some of the latest releases in equine science. These scientific equine papers have provided some interesting information sure to spark debate and inform our equine management and training practises; including a most important paper which provides evidence that horses ridden in hyperflexion may experience difficulty breathing because of airway obstruction.

Factors in Horse Training

Does learning performance in horses relate to fearfulness, baseline stress hormone, and social rank?

By Janne Winther, Line Christensen Peerstrup Ahrendt, Randi Lintrup, Charlotte Gaillard, Rupert Palme, Jens Malmkvist

“The ability of horses to learn and remember new tasks is fundamentally important for their use by humans. Fearfulness may, however, interfere with learning, because stimuli in the environment can overshadow signals from the rider or handler. In addition, prolonged high levels of stress hormones can affect neurons within the hippocampus; a brain region central to learning and memory. In a series of experiments, we aimed to investigate the link between performance in two learning tests, the baseline level of stress hormones, measured as faecal cortisol metabolites (FCM), fearfulness, and social rank. Twenty-five geldings (2 or 3 years old) pastured in one group were included in the study. The learning tests were performed by professional trainers and included a number of predefined stages during which the horses were gradually trained to perform exercises, using either negative (NR) or positive reinforcement (PR). Each of the learning tests lasted 3 days; 7min/horse/day. The NR test was repeated in a novel environment. Performance, measured as final stage in the training programme, and heart rate (HR) were recorded. Faeces were collected on four separate days where the horses had been undisturbed at pasture for 48h. Social rank was determined through observations of social interactions during feeding. The fear test was a novel object test during which behaviour and HR were recorded.

Performance in the NR and PR learning tests did not correlate. In the NR test, there was a significant, negative correlation between performance and HR in the novel environment (rS=−0.66, P<0.001, i.e. nervous horses had reduced performance), whereas there was no such correlation in the home environment (both NR and PR). Behavioural reactions in the fear test correlated significantly with performance in the NR test in the novel environment (e.g. object alertness and final stage: rS=−0.43, P=0.04), suggesting that performance under unfamiliar, stressful conditions may be predicted by behavioural responses in a fear test. There was a negative correlation between social rank and baseline stress hormones (rS=−0.43, P=0.04), i.e. high rank corresponded to low FCM concentrations, whereas neither rank nor FCM correlated with fearfulness or learning performance. We conclude that performance under stressful conditions is affected by activation of the sympathetic nervous system during training and related to behavioural responses in a standardised fear test. Learning performance in the home environment, however, appears unrelated to fearfulness, social rank and baseline FCM levels.”

http://www.journals.elsevierhealth.com/periodicals/applan/article/S0168-1591(12)00168-2/abstract

Equine Welfare

Effect of head and neck position on intrathoracic pressure and arterial blood gas values in Dutch Warmblood riding horses during moderate exercise.

By Sleutjens J, Smiet E, van Weeren R, van der Kolk J, Back W, Wijnberg ID.

“OBJECTIVE:To evaluate the effect of various head and neck positions on intrathoracic pressure and arterial oxygenation during exercise in horses.

ANIMALS:7 healthy Dutch Warmblood riding horses.

PROCEDURES:The horses were evaluated with the head and neck in the following predefined positions: position 1, free and unrestrained; position 2, neck raised with the bridge of the nose aligned vertically; position 4, neck lowered and extremely flexed with the nose pointing toward the pectoral muscles; position 5, neck raised and extended with the bridge of the nose in front of a vertical line perpendicular to the ground surface; and position 7, neck lowered and flexed with the nose pointing towards the carpus. The standard exercise protocol consisted of trotting for 10 minutes, cantering for 4 minutes, trotting again for 5 minutes, and walking for 5 minutes. An esophageal balloon catheter was used to indirectly measure intrathoracic pressure. Arterial blood samples were obtained for measurement of Pao(2), Paco(2), and arterial oxygen saturation.

RESULTS:Compared with when horses were in the unrestrained position, inspiratory intrathoracic pressure became more negative during the first trot (all positions), canter and second trot (position 4), and walk (positions 4 and 5). Compared with when horses were in position 1, intrathoracic pressure difference increased in positions 4, 2, 7, and 5; Pao(2) increased in position 5; and arterial oxygen saturation increased in positions 4 and 7.

CONCLUSIONS AND CLINICAL RELEVANCE:Position 4 was particularly influential on intrathoracic pressure during exercise in horses. The effects detected may have been caused by a dynamic upper airway obstruction and may be more profound in horses with upper airway disease.”

http://www.ncbi.nlm.nih.gov/pubmed/22452499

More information on the above paper can be found at http://www.thehorse.com/ViewArticle.aspx?ID=20201

On the significance of adult play: what does social play tell us about adult horse welfare?

By Martine Hausberger, Carole Fureix, Marie Bourjade, Sabine Wessel-Robert and Marie-Annick Richard-Yris

“Play remains a mystery and adult play even more so. More typical of young stages in healthy individuals, it occurs rarely at adult stages but then more often in captive/domestic animals, which can imply spatial, social and/or feeding deprivations or restrictions that are challenging to welfare, than in animals living in natural conditions. Here, we tested the hypothesis that adult play may reflect altered welfare states and chronic stress in horses, in which, as in several species, play rarely occurs at adult stages in natural conditions. We observed the behaviour (in particular, social play) of riding school horses during occasional outings in a paddock and measured several stress indicators when these horses were in their individual home boxes. Our results revealed that (1) the number of horses and rates of adult play appeared very high compared to field report data and (2) most stress indicators measured differed between ‘players’ and ‘non-players’, revealing that most ‘playful’ animals were suffering from more chronic stress than ‘non-playful’ horses. Frequency of play behaviour correlated with a score of chronic stress. This first discovery of a relationship between adult play and altered welfare opens new lines of research that certainly deserves comparative studies in a variety of species.”

http://www.springerlink.com/content/a773802p37590541/

Training the Ridden Horse

Horse walker use in dressage horses

By T.J. Walker, S.N. Collins and R.C. Murray

“Horse walkers have become popular in the modern exercise regime for dressage horses, however recent investigations of injury risk factors have indicated a significant association between horse walker use and lameness. A detailed telephone questionnaire was conducted to document horse walker usage and assess whether horse walker use could predispose dressage horses to lameness. Information on horse walker features and use, and individual horse lameness history was recorded. Chi-squared tests were performed to identify horse walker variables associated with lameness. Although analyses failed to establish a direct link between lameness and any specific horse walker feature, the high proportion of lame horses in this study suggests that there is an underlying and, as yet, unidentified cause of lameness related to horse walker usage.”

http://wageningenacademic.metapress.com/content/j3q3511435340324/

The effect of double bridles and jaw-clamping crank nosebands on temperature of eyes and facial skin of horses

By Paul McGreevy, Amanda Warren-Smith and Yann Guisard

“Any apparatus that restricts a horse’s movement can compromise welfare. Eye temperature as measured remotely using infrared thermography is emerging as a correlate of salivary cortisol concentrations in horses. This article explores the effect on the temperature of the eyes and facial skin of horses wearing devices that restrict jaw movements. In certain equestrian disciplines, unacceptable equine oral activity, such as gaping of the mouth, is penalized because it reflects poor training and lack of compliance. This explains the wide range of nosebands and flash straps designed to prevent the mouth opening. Some of these nosebands are banned from higher-level dressage competitions in which double bridles are mandatory, possibly because they are regarded as restrictive. Nevertheless, the current international rules overlook the possibility that noseband can appear innocuous even though some designs, such as the so-called crank noseband, can be ratcheted shut to clamp the jaws together. Some equestrian manuals and competition rule books propose that “two-fingers” be used as a spacer to guard against overtightening of nosebands but fail to specify where this gauge should be applied. The vagueness of this directive prompted us to undertake a small random survey of the finger dimensions of adult men (n = 10) and women (n = 10). There were significant sex differences in the measurements of fingers of adults (P < 0.001), thus illustrating that the “two-finger rule” is not a reliable guide for standardized noseband fastening. Infrared thermography was used to measure the temperature of facial skin and eyes of adult horses (n = 5) wearing a double bridle with and without a cavesson noseband.

A taper gauge was developed based on the mean circumference of adult index and middle fingers (9.89 ± 0.21 cm), and this was used as a spacer at the nasal planum or beside the mandible when tightening the noseband. The nosebands were fastened significantly tighter when the taper gauge was used beside the mandible than at the nasal planum (P = 0.02). Wearing double bridles and nosebands that had been tightened with and without the taper gauge caused an increase in eye temperature compared with baseline values (P = 0.012), and the tighter the noseband was fastened, the cooler the facial skin of the horse (and, presumably, the greater the impairment of vascular perfusion) when compared with baseline values (P = 0.016). This study suggests that horses wearing double bridles and tight nosebands undergo a physiological stress response and may have compromised vascular perfusion. Consequently, on welfare grounds, the use of nosebands that cause any constriction of jaw movement should be reviewed as soon as possible.”

http://www.journalvetbehavior.com/article/S1558-7878(11)00143-2/abstract

Pilot study of behavior responses in young riding horses using 2 methods of making transitions from trot to walk

By Agneta Egenvalla, Marie Eisersiöb and Lars Roepstorffc

“According to the principles of negative reinforcement, when an aid has been given to an animal, it should be released as soon as the desired response has been achieved, and, if performed well, may be associated with fewer conflict behaviors than otherwise. In riding, pressure in the horse’s mouth from the bit is used to give signals to the horse, and both rein tension and patterns of releasing this tension will vary. The aim of this pilot study was to study horse behavior during 2 different methodologies used to shape relatively naïve horses to a deceleration signal while making downward transitions from trot to walk. Method 1 involved relief from rein tension at the first attempt to perform a correct response (M1), and method 2 entailed that rein tension was relieved at the completed correct response (M2). Four horses were ridden by 4 riders over 4 days (1 rider each day), and each horse made 10 transitions each day for each method, which produced 320 transitions. Rein tension was recorded, and horse behavior and rider signal behaviors were evaluated from video recordings. Horse behavior was divided into the following 3 different categories: “pushing against the bit,” “moving away from the bit,” and “decelerating.” Linear models were constructed tracking the percent of the transition time that horses demonstrated at least 1 behavior in the “pushing against the bit,” “moving away from the bit,” and “decelerating” categories, and with random effects for rider, horse, and transition number nested within horse. Fixed effects analyzed were the methods, proportion of the transition time above 30 N for each rein, and the rider signal behaviors. M1 and M2 had on average 19% (standard deviation: 16) and 38% (standard deviation: 23) of the time with >30 N per rein, respectively. In the models for the “pushing against the bit” behaviors, M2 increased rein tension and “exerting pressure on the reins” increased the level of these behaviors. “Releasing pressure” interacted with “pulling back on the reins”; this combination was associated with an increased level of “pushing against the bit” behaviors. The “decelerating” behavior was associated with lower rein tension. In the “decelerating” behavior models, “pulling back on the reins” led to decreased “decelerating” behavior, whereas “still hand” and “releasing pressure” led to increased “decelerating” behavior; however, the interaction “pulling back on the reins” and “releasing pressure” led to decreased “decelerating” behavior. “Moving away from the bit” had no significant determinants. We concluded that fewer “pushing against the bit” behaviors were created by M1 and that a lower rein tension was associated with the “decelerating” behavior. Reinforcing the horse’s attempts, to assist in finding the correct response, benefits the welfare of the horse, and importance of a light hand should be continuously emphasized during riding education.”

http://www.sciencedirect.com/science/article/pii/S1558787811001481

Equipment and training risk factors associated with ridden behaviour problems in UK leisure horses

By Jo Hockenhull and Emma Creighton

“Ridden behaviour problems are prevalent in the UK leisure horse population and may have implications for horse welfare and rider safety. This study aimed to identify risk factors associated with ridden behaviour problems in UK leisure horses from the training approaches and equipment used with them. An Internet survey was used to collect data on 1326 horses from a convenience sample of leisure horse owners. The survey asked owners to report the frequency their horses displayed fifteen ridden behaviour problems over the previous week. Data on the frequency of occurrence of behaviour in four components of related ridden behaviour problems were explored for association with details of the horse’s working life, including the type of tack, equipment and training used, and the frequency the professional services of saddlers and farriers were employed using logistic regression analyses. Behaviour data were generated for 791 individual horses. Risk factors associated with the ridden behaviour problems emerged as three themes. One related to the design and fit of the saddle, with dressage and working hunter saddles associated with a reduced risk of ridden behaviour problems compared to general purpose saddles. The horse’s footcare and shoeing regime was associated with three of the four groups of behaviour problems. An extended interval (seven weeks or more) between farrier visits was associated with an increased risk of discomfort behaviour. Taking an outcome-centred approach to training, for example through the use of artificial training aids, was associated with an increased risk of behaviour problems while spending more time with the horse outside of training situations, a more horse-centred approach, was associated with a reduced risk of problems. Further research is required to understand the causal relationships behind these associations, with the aim of improving the welfare of the horse and the well-being and safety of its rider.”

http://www.journals.elsevierhealth.com/periodicals/applan/article/S0168-1591(12)00020-2/abstract

I hope you enjoy this collection of abstracts as much as I did. If you have a question about any of the abstracts or the terminology used, please feel free to leave a comment or email me and I will happily answer your questions.

Emma Lethbridge

(Emma@theequineindependent.com or E.M.Lethbridge@shu.ac.uk)

Oct 262010
 

With the explosive increase in people using social media, such as Facebook, I find myself being sent an array of video clips from You Tube. Usually these are accompanied by a message that says “Isn’t this amazing?”, “Isn’t this funny?” or “Isn’t this terribly cruel?”. However, often the message is totally inappropriate considering the content. Although the sender thinks I’ll be impressed, in the, grammatically incorrect, words of the song ‘It don’t impress me much’.

Flying donkey’

One of the first things I was sent with a totally inappropriate comment was a photo of a donkey hitched to a cart with a load so heavy that the donkey is hanging in the air from his/her harness (www.onefunsite.com/donkey.shtml). My friend sent me this picture with a message saying “This is so funny, I know you like donkeys so you’ll love this!”. I didn’t love it or find it amusing. It so vividly illustrates some of the problems working equines face – hard work, heavy loads, often in extremes of temperatures with little opportunity for shade or rest. Their owners are usually dependent on these animals to earn enough money to feed their families. I was shocked and saddened that this was being circulated as something funny – and that my friend thought that I’d actually like it!

Nearly 10 years later I had just started working at the World Society for the Protection of Animals (WSPA) and a video version of the same scenario was circulating – as a ‘funny video’ (http://www.youtube.com/watch?v=0gCs8-PU4qg). I wrote to one of the newspapers that was promoting it in their online video section: I highlighted the plight of the donkey in the scene and they replied saying that it’s what their readers enjoy! Judging by the thousands of views and comments, they were right.

Last year I was visiting The Palestinian Territories in my role at WSPA, working with the Palestine Wildlife Society in their community project to improve equine welfare. They are partnering with donkey owners in Bethlehem and surrounding areas to explore together what changes they could make to the way they manage and care for their donkeys, mules and horses to improve their welfare and quality of life. One of the community representatives approached me with a mobile phone and showed me the same video of the donkey mentioned above. I thought that he also finds it ‘funny’ and that I’d use the opportunity to discuss overloading with the owners. However, he showed me the clip and then said, through an interpreter, “Isn’t it so terrible? Does the owner not care? Does he know not to load the cart that much?” I was very moved – at least not everyone finds it amusing.

Does the means justify the end?

A more recent example of a video clip with an inappropriate message is a video of a horse competing at high level dressage. Apparently the horse was trained using clicker training and I was sent this as an example of something impressive because so many people know I promote reward-based training methods.

Watching the video I observed a highly stressed horse, mouthing, swishing tail, very tense. I was not impressed. “But he was trained using clicker training” – Don’t get me wrong I think that in the right hands clicker training can be a wonderful and positive training experience for human and horse. However, clicker training can also be done in a way that is not a positive experience for the horse. Maybe the horse had learnt some movements through clicker training, but was it done well? Did the trainer work for long periods frustrating the horse to get the desired movement? Was the horse given the opportunity to walk away to graze or have a break when he wanted to? The video showed a very ‘unhappy’ horse, irrespective of if clicker training was used.

Naturally nagged

A third, and final, example is a natural horsemanship video that was beautifully edited, with soulful music, showing a lady riding a horse bareback and bridle-less. The horse lies down on command and other similar tricks – accompanied by a message “How lovely, something for us all to aspire to”. Again, what does observing the horse tell us? To me the horse looked hyper-vigilant and tense, looking for every subtle cue from his owner. This is most likely the result of being trained so extensively using negative reinforcement that the horse has stopped thinking for himself or exercising choice and has become ‘shut down’, like a robot. Impressive perhaps – but only because this shows how horses can learn to respond to subtle cues.

Impressions

Of course it is generally inappropriate to make assumptions about what happens during the rest of the animals’ lives and training sessions apart from just the few minutes in these videos. However, we should always encourage people to consider what the horses are telling us in such footage rather than the message from the person sharing it.

It is interesting and sad that people are so impressed by what we can make horses do and not by what they do just by being horses. Why do we find it so impressive when a human can train a horse lie down? Because people intrinsically know that as a prey species this is a big deal for a horse? Many people consider dressage to take the horse’s natural movement and put it under control of the rider. However, behaviour is only normal and natural if it is done in context and for the ‘normal’ amount of time. Thus a horse in a field spinning quickly to avoid a threat is natural, spinning repeatedly as a trick is not – yet people so often find such abnormal behaviour impressive.

So, what would impress me?

What would I forward on to other people as an impressive horsemanship? What would I aspire to? I think the answer goes something like this: A video clip showing a group of horses grazing in a large open space. A human approaches and one of the horses leaves the herd and approaches the person with relaxed body language suggesting this is because he wants to, not because he feels he has to. The horse is greeted with a big scratch. Then horse and owner walk off together, exploring the landscape, sometimes walking, sometimes riding. If they meet an obstacle that the horse is unsure of the human lets the horse take his time to consider the situation, rewards calm behaviour and they calmly continue on their way. The horse is allowed to graze and browse, the human might take time to photograph the landscape but the horse quietly waits because they are used to spending such calm time together and as such he isn’t having to watch the human for every small command she might give. This is the type of video I would think as something to aspire to – but I suspect it would never get a million hits on YouTube.

Sep 232010
 

Am I the only person to be concerned about the increasing trend to control and overcome natural equine behaviour? Now before all the training people leap on me, yes, I do know that all our interactions with horses have an effect on their behaviour, and that all training is designed to do just that. I’m not talking about that, though. What concerns me is the idea that normal horse behaviours are problems, for which you need a solution that – very handily – someone can sell you. I’m not sure whether the demand has come from horse owners and riders, from manufacturers trying to sell products, or simply from the modern desire for a quick and easy fix (such as using herbicides instead of weeding the garden).

In the 6000 years since horses became domesticated animals we have done much to bend their wild natures to our own ends. But it seems that it’s only in the last few years in the developed countries of the world, as the idea of the horse as working partner has faded from living memory, that we have been trying to suppress their natures altogether. Rather than accepting that horses are nervous, flighty and sometimes argumentative creatures with strong social and sexual drives, we have decided that it’s acceptable, even necessary, to treat those natural instincts as problems or conditions that need to be cured or controlled. Hence the whips, spurs, tight nosebands, severe bits, training aids and food supplements.

A recent study by Hockenhull and Creighton (2010) found that in a survey of over 1000 non-professional horse owners in the UK, 79% used one or more artificial aid such as a martingale, or noseband other than a simple cavesson, and 85% routinely fed dietary supplements. Astonishingly, almost one in three owners – 27% – gave their horses four or more dietary supplements along with their feed.

There seems to be a widespread perception (Hockenhull & Creighton 2010; McBane 2010) that the apparent increase in horses behaving inappropriately, and the proliferation of ways to modify their behaviour that do not rely on the skills of the rider, is because many more horses these days are owned by novices who use artificial aids and dietary supplements to help with problems that they lack the skills or knowledge to solve. However, this survey showed quite clearly that the riders using the largest number of artificial aids, and giving the most dietary supplements, were those who described themselves as committed amateurs, rather than leisure riders, and who rated their level of skill as ‘high’. These products, it seems, are used most by the very riders who ought to have the skills and knowledge not to need them.

Many years ago, the sports writer Simon Barnes wrote a monthly column for the UK magazine Horse & Rider. One sentence that he wrote has stayed in my mind ever since: “The whip is an admission of failure.” He meant that by carrying a whip, he was, in effect, saying “my own body and legs and hands and personality are not

good enough to motivate this horse to go forward willingly.” The trouble is that we have an equestrian culture – and this recent study confirms it – in which fierce bits, and crank nosebands, and training gadgets that resemble bondage outfits, and whips, and, more than anything else, spurs, are seen as the badges of honour of the skilled riders, the serious, proper riders, as opposed to the ‘happy hackers’. How would it be if everything changed, so that using an artificial aid proclaimed to the world, “I’m not a good enough rider to fix this problem without this gadget.”? What would it take to make that happen?

This isn’t a perfect world; all horse-rider relationships are works in progress; and none of us are quite as good as we’d like to be, but I do think horses in general would have a better time if we could change our culture to one of using as little equipment as necessary, rather than as much as possible, and if more people were in the habit of questioning what they do and the kit they use. For example: Does my horse really need this? Would something else, like some extra riding lessons, or less hard feed for the horse, be another way to solve the problem? Am I just using this equipment because I’ve always used it, or everyone else uses it, or the professional riders I admire use it?

I always feel sceptical about the merits of the various feed supplements designed to modify horse behaviour and suspect that they work largely by convincing the rider that the horse will be calmer, or less bolshy, or whatever, while taking the supplement, and so she rides with more confidence or tact, and so the horse behaves better. The causes of inappropriate behaviour are likely to lie in the realm of inappropriate feeding, housing, exercising, training or care, and it seems improbable that small scoops of this or that herb, or vitamin mix, or other magic powder can have much effect if some major aspect of the horse’s life is wrong. Indeed, the labelling on the packaging of many supplements gives the impression that nothing is guaranteed: phrases such as ‘believed to be beneficial for X’, or ‘may help horses suffering from X’, or ‘traditionally used for treating X’, or ‘to support the function of X’ enable the manufacturer to suggest that their product will help with something while not making any direct claims that would get them into trouble with Trading Standards.

When you use herbs, what you are giving your horse is an unknown dose of an unknown number of active ingredients, of unknown strength and in many cases unknown effect, with unknown side-effects and interactions with other supplements and prescribed medicines and, in products from less-reputable companies, unknown contaminants including heavy metals and prescription drugs. Skeptvet (2010) gives a comprehensive and alarming list of publications on the subject. However, whether riders are inadvertently poisoning their horses with these products or not, the fact remains that the majority of riders seem to think it’s OK to use drugs to modify their horse’s behaviour – because that’s what these products essentially are. Is that really an acceptable way to treat these animals that we say we love?

I do suspect that a lot of behavioural or temperament problems in horses could be solved not by adding substances to their concentrate feed but by giving them less of it, and by giving them more exercise and a more varied and exciting life.

The underlying problem seems to be that many people find the natural behaviour of horses difficult to deal with, or frightening, or in some way undesirable, and this is possibly because it’s so different from our own behaviour. About ten years ago, Equine Behaviour Forum member Emma Creighton conducted a scientific study into the aspects of horse and pony temperament that are important to riders and handlers. Her findings were that most of the respondents preferred horses who were in the mid-range of emotional reactivity, were highly sociable and responsive to humans, and were extrovert and open to new experiences. These preferences were independent of rider age, years of experience or level of skill. What came as a surprise was that the horse temperament described as ideal by most people was more a description of the average dog than the average horse. Emma suggested that since we have shared more years of our history with dogs than with horses, we perhaps relate better towards, and have an inbuilt predisposition towards, animals that behave like dogs. Is this why we try so hard to stop horses behaving like horses?

By Alison Averis

Alison Averis is the Editor of Equine Behaviour, the Journal of the Equine Behaviour Forum. 

If you find these questions interesting, you would probably enjoy being a member of the Equine Behaviour Forum and joining in the correspondence in our quarterly magazine. See www.gla.ac.uk/external/ebf/ for more information.

References

Creighton, E (2003). Equine temperament and welfare. Equine Behaviour 59, 13-16.

Hockenhull, J & Creighton, E (2010). Can we blame the widespread use of artificial training aids and dietary supplements in the UK leisure horse population on novice owners? In Proceedings of the 6th International Equitation Science Conference, p40. www.equitationscience.com

McBane, S (2010). Conflict behaviours – causes, effects and remedies. Equi-Ads, September 2010, p40. www.equiads.net

Skeptvet (2010). Risks of herbs and supplements finally getting some attention.  www.skeptvet.com/blog/2010/02/344/

Jul 142010
 

Summer is a great time for riders and horse owners alike, the long days and hopefully sunny weather bring greater opportunities for spending time with our much loved, four-legged friends. However, for some horse and pony owners summer can also be a worrying time and the start of an ongoing battle with their horse’s waistline. Despite our best intentions summer comes and our horse’s stomachs begin to expand like balloons at a birthday party. Some horses come out of winter the perfect weight but can start to inflate the minute the first spring grass appears, for others the issue of weight is a constant factor, especially for those with pony or cold blood genes in their DNA. If you own a horse who is a ‘good doer’ and he can seemingly live off air alone, it can seem like no management strategy or exercise regime will stop the spread. So what are the real risk factors of obesity and how can we prevent our horse’s becoming overweight this summer?

Obesity, in both horses and humans, is becoming an epidemic in the UK. The horse charity, World Horse Welfare, estimates that between 35 and 45 per cent of the UK’s 1.35million horses are obese[1]. There are many worrying disorders that obesity is associated with, including; Laminitis, Equine Metabolic Syndrome and oxidative stress[2]. All of the above disorders are of grave concern to owners! Laminitis is inflammation of the digital laminae of the hoof. The digital laminae are necessary for suspension of the skeleton within the hoof and spread the concussive forces experienced by the hoof during the horse’s locomotion. Inflammation of the laminae weakens the hoof and can have devastating effects on the horse’s physiology included; sinking and rotation of the coffin bone (known as founder), separation of the hoof wall from the hoof capsule, rotation of the coffin bone and penetration of the coffin bone through the sole of the hoof[2]. These complications of Laminitis can cause permanent lameness and loss of use and can, in the worst cases, result in euthanasia.

Equine Metabolic Syndrome (EMS) is characterised by obesity, insulin resistance and intermittent bouts of Laminitis[2]. Obese horses suffering with EMS become gradually more resistant to the action of insulin – insulin is a hormone which triggers cells in the liver, muscles and fat to take up glucose from the blood stream and store it as glycogen. This resistance to insulin consequently causes abnormally high levels of insulin to be secreted when the horse ingests food, especially foods high in sugars such as concentrate. In both horses and humans, insulin resistance seems to be correlated with obesity and the altered metabolism of fats[3]. However, unlike in the human species, insulin resistance in horses due to obesity is very rarely type 2 diabetes (diabetes in horses is usually only associated with Cushing’s syndrome), instead insulin resistance is postulated to be a contributing factor to Laminitis and potentially certain vascular diseases[3].

Laminitis and EMS are not the only concerns for the owners of horses who put on weight easily. Several adverse health effects can be correlated with the horses gain of fat deposits. The horse may become intolerant of exercise and his athleticism will be compromised. Just as obese humans can experience oxidative stress, fatigue and increased concussion on joints during exercise, horses can also experience these consequences of obesity. The performance of horses competing in races of duration 1 mile to 160km has been found to correlate to the horse’s body condition[4-6]. The obese horse may also experience thermoregulatory difficulty, although fat deposits will insulate a horse during the winter months, in the summer excess fat can prevent the horse from effectively dissipating heat resulting in the horse overheating[7]. Finally, abnormal reproductive performance has also been observed in obese mares [8], obesity can cause unnecessary complications in pregnancy and is therefore a welfare concern for both mare and foal. The risks of horse obesity are very worrying for horse owners so why are so many horses becoming obese in the UK?

Although ignorance on behalf of the horse owner is sometimes the underlying cause of equine obesity, most owners are aware when their horses are becoming overweight. Even the least observant owner can see their horse’s stomach increasing in girth, the neck becoming larger and developing a crest, and fat deposits occurring on the shoulders and flanks, but often the owner is struggling to set up a management regime that can control the weight of the horse. Owners are often restricted by factors such as; the residence of the horse, the management of the horse’s pasture or other environmental factors. But do not despair, here are a few ideas which could help to prevent the summertime spread this year.

1. Knowing how much you horse should weigh, finding an accurate way to measure your horse’s weight and keeping a record of change.

The first thing you will need to know when you embark on the battle with obesity is your horse’s ideal weight. Without a goal weight for your horse any measurement of the horse’s weight is going to be arbitrary. Although all horses differ with regards to their ideal weight, approximate ideals for your horse’s type and height can be found below. For each height range there is a range of ideal weights, if your horse is the top end of the height range or a draught bred then the horse’s ideal weight will be the top end of the range, and vice versa.

Height in hands11121314151617
Ideal weight in kg120-230230-290290-350350-420420-520520-600600-725

(Adapted from Baileys Horse feeds [9])

Once you know your horse’s ideal weight you will need to be able to measure the horse’s weight. There are many ways to measure a horse’s weight, some more accurate than others. The most accurate method of measuring a horse’s weight is a weighing bridge, however unless you are liveried at a very well equipped yard or have convenient access to veterinary facilities it is unlikely that you will have access to a weigh bridge.

A more common method of measuring a horse’s weight is by using a weight tape. Weight tapes are placed around the girth of the horse, just behind the withers, and give an estimation of the horse’s weight based on the circumference of the girth . The accuracy of these tapes is debatable however, the tape provides a quantitative measure of weight which can be recorded and which will provide notice of the horse’s weight changing over time. Weight tapes can be brought from most equestrian stores, and on occasion tapes specifically designed for draught horses and ponies can be acquired. Buying a tape designed for your horse’s body type will increase the accuracy of the measurement.

As an alternative measure of the horse’s weight and condition there are body condition scoring systems, one of the most popular is based on work by Henneke et al (1983)[10]. Henneke et al’s body condition scoring uses the observation and ranking of the fat tissue present on specific areas of the body to score the condition of the horse. The areas observed for the accumulation of fatty tissue are; the neck, ribs, back, shoulder, wither and the top of the tail. When all the areas are taken into consideration an overall condition score, between 1 and 9, is attributed to the horse – 1 being of very poor condition with no fatty tissue present in the scored areas and 9 being of obese condition with significant fatty deposits visible on the . A picture chart explaining Heneke’s body condition scoring can be found at – http://www.admani.com/allianceequine/images/bodyconditionscoring/horse%20body%20condition%20score%20card.pdf , this picture chart is a good summary of the observations that should be made during condition scoring. A printable record sheet for Henneke et al’s body condition scoring mechanism can also be found at this link – http://www.blm.gov/pgdata/etc/medialib/blm/wo/Information_Resources_Management/policy/im_attachments/2009.Par.52473.File.dat/IM2009-041_att1.pdf

There are potential problems with using body condition scoring as a method of weight measurement in horses. Scoring body condition is a subjective method and it is therefore possible for owners to over or under score their horses and, if no additional methods of weight measurement are used, it is sometimes difficult to ascertain whether the horse is indeed of a healthy weight. Ideally two or three people should score the horse independently and the middle score taken to be correct, such a precaution will help to minimise the effect of subjective bias. The body score of the horse can be recorded and over time any change in the horse’s condition can be monitored accordingly.

Whichever method of weight measurement you decide to use with your horses, try to keep a record at least once a month of the horse’s weight. This record keeping will allow you to see changes in the horse’s condition early and allow you to change his management before serious complications arise.

2. Cutting out the concentrate feed!

This one may seem obvious, but if your horse is overweight it is not necessary to supplement the horse’s roughage feed with concentrate! Removing concentrate feed, and therefore unnecessary calories, from the diet of the horse will help to prevent, or treat, obesity. If the horse is feed ad-lib, quality roughage including pasture, and is a good weight it is not necessary to supplement the horse’s diet with calorie-dense, grain concentrate. Should the horse’s pasture and roughage be of poor quality it may be a prudent idea to add a vitamin and mineral supplement to the horse’s feed, this will prevent any dietary malnutrition. As long as the horse maintains weight and does not become thin, and is not in a heavy exercise regime, i.e. intermediate eventing or above, the horse does not require extra calories. Should the horse be currently in a routine where he is used to receiving concentrate meals at certain times and will become distressed if his routine is changed then some molasses-free chaff or grass chop can be feed at these times to placate him.

3. Pasture maintenance

There are many aspects of pasture maintenance that can be managed to help combat obesity and weight gain in the horse. Below I will tackle the most important factors of pasture maintenance that can be managed by horse and land owners –

The right grass?

Many grassland species have been selectively produced to feed domestic livestock on intensive grazing patterns, as such many grass species commonly found in horse grazing are high in sugars. Grass designed to keep livestock at a good weight is often too rich for horses who are designed by evolution to each a great amount of poorer roughage. See below abstract by Menard et al (2001)[11] on the comparative forage intake of cattle and horses.

“Equids are generalist herbivores that co-exist with bovids of similar body size in many ecosystems. There are two major hypotheses to explain their co-existence, but few comparative data are available to test them. The first postulates that the very different functioning of their digestive tracts leads to fundamentally different patterns of use of grasses of different fibre contents. The second postulates resource partitioning through the use of different plant species. As domestic horses and cattle are used widely in Europe for the management of conservation areas, particularly in wetlands, a good knowledge of their foraging behaviour and comparative nutrition is necessary.

In this paper we describe resource-use by horses and cattle in complementary studies in two French wetlands. Horses used marshes intensively during the warmer seasons; both species used grasslands intensively throughout the year; cattle used forbs and shrubs much more than horses. Niche breadth was similar and overlap was high (Kulczinski’s index 0·58–0·77). Horses spent much more time feeding on short grass than cattle. These results from the two sites indicate strong potential for competition.

Comparative daily food intake, measured in the field during this study for the first time, was 63% higher in horses (144 gDM kg W−0·75 day−1) than in cattle (88 gDM kg W−0·75 day−1). Digestibility of the cattle diets was a little higher, but daily intake of digestible dry matter (i.e. nutrient extraction) in all seasons was considerably higher in horses (78 gDM kg W−0·75 day−1) than in cattle (51 gDM kg W−0·75 day−1). When food is limiting, horses should out compete cattle in habitats dominated by grasses because their functional response is steeper; under these circumstances cattle will require an ecological refuge for survival during winter, woodland or shrubland with abundant dicotyledons.

Horses are a good tool for plant management because they remove more vegetation per unit body weight than cattle, and use the most productive plant communities and plant species (especially graminoids) to a greater extent. They feed closer to the ground, and maintain a mosaic of patches of short and tall grass that contributes to structural diversity at this scale. Cattle use broadleaved plants to a greater extent than horses, and can reduce the rate of encroachment by certain woody species.”

Menard et al (2001)


As horses can consume great amounts of forage it is vital that the high-sugar, easily digestible and nutrient rich grass varieties fed to domestic livestock species are not feed in high quantity to horses. Obesity and laminitis will be difficult to avoid on rich grazing without restricting grazing, which in turn would be detrimental to the welfare of the horse. Sugars present in grass species, especially fructans have been correlated with laminitis in horses. Below is an informative short article on fructans from www.equinescienceupdate.co.uk.

Recent studies suggest that fructans might be involved in pasture-induced laminitis in horses. Fructans are storage molecules produced by the grass when it produces more sugars by photosynthesis than are needed for immediate use. Fructans are poorly digested in the foregut of the horse. If large quantities reach the hindgut they are rapidly fermented by the microorganisms, leading to a cascade of events that may result in laminitis.

In a three year study Jürgen Grässler and Uwe von Borstel, working at the Landwirtschaftskammer in Hannover, Germany, looked at fructan content in the species of grasses that are commonly found in horse pasture. They harvested grass samples every two or three weeks during the growing season. Samples were collected at 11.00 each morning to prevent the results being influenced by time of day.

Dr Grässler presented their findings at the Equine Nutrition Conference held earlier this month in Hannover. They found that Lolium perrene (Perennial ryegrass) and Lolium multiflora (Italian ryegrass) contain the highest amounts of fructans – an average throughout the year of 5.7% on a dry matter basis. However, they found that the fructan content varied throughout the year, being highest in May and October. The fructan content fell during the summer. They also found a difference between strains of perennial ryegrass. One strain (“Anton”) had the highest fructan level of 14.2%DM in autumn 2003 and 13.6% DM in spring the same year.

All other pasture grasses contained low fructan concentrations – on average about 3.5% DM. Again, the highest fructan concentration was found in the first growth in May and in October. The fructan content of the grass was lowest during the summer.

The second part of the study looked at the fructan content of grass mixes that might be used for horse pasture. Grässler and von Borstel found that mixtures with a high proportion of Lolium perrene gave the highest fructan levels . The highest levels were found in pastures containing only Lolium perrene (15.2%). During the growing season the highest fructan content was measured in late June (11.4% DM average) and in October.

Grässler and von Borstel conclude that grass mixes with high amounts of Lolium perrene may contain high fructan concentrations, especially in spring and autumn, and are less suitable for feeding horses predisposed to laminitis.

To minimise the risk of laminitis they suggest that grass mixtures with reduced quantities of Lolium perrene should be used. Pastures with forage grasses such as Alopecurus pratensis (Meadow Foxtail) and Phleum pratense (Timothy) as the main components are suitable to produce low fructan concentrations.

Reference: Fructan content in pasture grass. Jürgen Grässler and Uwe von Borstel. Proceedings Equine Nutrition Conference. Pferdeheilkunde (2005) 21, 75 – 76.”[12]

The key message of the above article is; when planning the reseeding of your pasture please consider the grass species you are using and choose low-sugar grass species, such as Meadow Foxtail and Timothy, which will protect your horses against obesity, insulin resistance and Laminitis. Herbs and legumes can also be included for variety and additional vitamin and mineral availability. Sugar-dense grasses used to feed domestic livestock, such as dairy cattle, should be avoided as they are not suitable for healthy horse grazing. Rye grass is the typical example and is currently very common in the pastures of Britain’s horses. If you are at the mercy of a land owner it may be possible through democratic negotiation to encourage the seeding of horse friendly grass species.

Pasture fertilisation

Traditionally pasture fertilisation is recommended in the spring and autumn months. It is suggested that proper fertilisation will provide pasture with the nutrients to produce a good quantity of grass cover, minimising weed growth. In addition it is postulated that the nutrients needed to provide horses with a healthy diet are also infused into the soil during fertilisation. However, the relationship between fertilisation and grass nutrition is not straight forward, especially when considering non-structural carbohydrate concentrations (sugars). It is often assumed that fertiliser increases the sugar content of grass, however, it is well noted in scientific journals that grass grown in an environment deficient in either nitrogen or phosphorus is observed to be significantly higher in sugars than grass grown in fertilised conditions [13, 14, 15, 16]. The discovery of this correlation between nitrogen availability and the sugar concentration in grass has led to the postulation that nitrogen maybe a limiting factor for growth and therefore if the grass becomes deficient in nitrogen, growth stops and, rather than being used for the production of new plant matter, fibre and energy, the sugars accumulate in the grass[17].

In her 2005 paper titled – A Review of Unlikely Sources of Excess Carbohydrate in Equine Diets, Kathryn Watts considers data collected on the effect of pasture fertilisation on the non-structural carbohydrate (NSC) concentrations of grass, and how pasture should managed to prevent an excess in sugar in the equine diet[17]. She writes “The following data was collected from the first cutting of forage from an established paddock of irrigated pasture at Rocky Mountain Research & Consulting, Inc. Each treatment was replicated 4 times in a randomized block design. The species represented are mostly Paddock meadow brome and Garrison meadow foxtail, which are standard commercial varieties in the area. Ammonia nitrate was broadcast in March, and irrigation was applied as needed for optimum growth to both fertilized and unfertilized plots. When the paddock was starting to head the end of May, samples for NSC were collected 4 PM, frozen immediately, and shipped frozen for analysis. A light frost occurred the night before sampling. The next day, 2 sq yards of plant material were hand clipped to ground level from each plot, and dried in an oven to obtain dry matter yield. The plots fertilized with ammonia nitrate yielded 3 times more dry matter, and were 29% lower in NSC concentration than unfertilized. This inverse relationship between nitrogen content and NSC concentration corroborates that found in plant science literature.

NSC %

Dry matter

Yield Tons

Dm/ acre

Pounds NSC /acre
35 lbs/acre

nitrogen as AmNO3

17.88 b1.8 a643 a
No nitrogen23.10 a.6 b277 b

Analysis by Dairy One, Ithaca, NY

The determination as to whether NSC concentration or pounds of NSC per acre is more important will be dependent on how the individual horse’s intake is managed. If a horse has continual access to pasture, it is possible to limit grass intake by starving the grass for nitrogen and overgrazing such that the amount of available forage does not exceed or even meet caloric needs. In this scenario, additional hay is often required. Because hay is generally lower in NSC than fresh grass, the higher concentration of NSC in nitrogen deficient grass may be offset by the lower concentration generally found in hay. In this type of situation, susceptible horse’s may be at increased risk of over indulging if the pasture is fertilized or irrigated, or a drought breaking rain occurs, which would then create more pounds of NSC per acre, while removing the limitations to intake imposed by slow grass growth.

If the caretaker were limiting intake by restricting access to grass, by use of grazing muzzle, portable fencing, or removal to a dry lot for part of the day, then fertilization, which decreases the concentration of NSC per mouthful of grass, would be the best option.” [17]

When considering whether it is healthier for your horses to fertilise your paddock or to leave it to grow organically it is necessary to consider whether the higher yield of grass obtained through fertilisation is likely to cause your horse to have higher sugar in his diet than the lower yield, higher sugar concentration grass of organic pasture? If your horse’s residential property has a low horse-acreage ratio, then it is possible that the high yield gained by fertilisation will create to much pasture for the horses to graze without becoming overweight. However, if there are a significant amount of horses grazing the pasture of your horse’s residence the extra grass yield of fertilised pasture should be spread between enough animals that the lower sugar concentration of fertilised grass is beneficial. Optimum fertilisation is a balancing act, one that must be considered carefully by horse owners.

To be continued….

Next time we will consider more pasture management ideas and exercise routines design to fight horse flab.

By Emma Lethbridge

(info@emmalethbridge.com)

References

[1] http://www.worldhorsewelfare.org/

[2] Johnson P.J., Wiedmeyer C.E., Messer N.T., Ganjam V.K. Medical Implications of Obesity in Horses—Lessons for Human Obesity. J Diabetes Sci Technol. 2009; 3(1): 163–174.

[3] Hoffman R.M., Boston R.C., Stefanovski D, Kronfeld D.S., Harris P.A. Obesity and diet affect glucose dynamics and insulin sensitivity in Thoroughbred geldings. J Anim Sci. 2003;81(9):2333–2342.

[4] Kearns C.F., McKeever K.H., Kumagai K., Abe T. Fat-free mass is related to one-mile race performance in elite standardbred horses. Vet J. 2002;163(3):260–266

[5]Lawrence L.M., Jackson S., Kline K., Moser L., Powell D., Biel M. Observations on body weight and condition of horses in a 150-mile endurance ride. J Equine Vet Sci. 1992;12:320–324.

[6]Garlinghouse S.E., Burrill M.J. Relationship of body condition score to completion rate during 160 km endurance races. Equine Vet J Suppl. 1999;30:591–595.

[7] Cymbaluk N.F., Christison G.I. Environmental effects on thermoregulation and nutrition of horses. Vet Clin North Am Equine Pract. 1990;6(2):355–372.

[8] Henneke D.R., Potter G.D., Kreider J.L. Body condition during pregnancy and lactation and reproductive efficiency of mares. Theriogenology. 1984;21:897–909.

[9] http://www.baileyshorsefeeds.co.uk/feedingexplained/calculator.htm

[10] Henneke D.R., Potter G.D., Kreider J.L., Yeates B.F. (1983). Relationship between condition score, physical measurements and body fat percentage in mares. Equine Vet J. 15(4):371-2

[11] Menard C., Duncan P., Fleurance G., Georges J-Y., Lila M. (2001). Comparative foraging and nutrition of horses and cattle in European wetlands. Journal of Applied Ecology. 39 (1); 120-133.

[12] Article at http://www.equinescienceupdate.co.uk/fructan.htm on the paper- Fructan content in pasture grass. Jürgen Grässler and Uwe von Borstel. Proceedings Equine Nutrition Conference. Pferdeheilkunde (2005) 21, 75 – 76.

[13] Smith D. Nonstructural Carbohydrates. In Butler G.W., Bailey R.W. ed. Chemistry and Biochemistry of Herbage, vol 1. London: Academic Press, 1973;105-155.

[14] Belesky D.P., Wilkinson S.R., Stuedemann J.A. The influence of nitrogen fertilizer and Acremonium coenophialum on soluble carbohydrate content of grazed and non-grased Festuca arundinace., Grass Forage Sci 1991;46:159-166.

[15] Donaghy D.J., Fulkerson W.J. The impact of defoliation frequency and nitrogen fertilizer application in spring on summer survival of perennial ryegrass under grazing in subtropical Australia, Grass Forage Sci 2002;57(4):351.

[16] Morvan-Bertrand A., Boucaud J., Prud’homme M. Influence of initial levels of carbohydrates, fructan, nitrogen and soluble proteins on regrowth of Lolium perenne . L. cv. Bravo following defoliation. J Exper Bot 1999;50:1817-1826.

[17] Watts K.A. A Review of Unlikely Sources of Excess Carbohydrate in Equine Diets. Journal of Equine Veterinary Science. 2005; 25(8): 338-344

May 142010
 

Dietary supplementation for horses is a vexed area where the scarcity of scientific studies, owners’ desires to do the best for their animals and enthusiastic advertising by manufacturers all conspire to make it difficult for anyone to know the best thing to do.

There is nothing inherently dodgy or implausible about vitamins and trace elements. They are essential to life. Strictly speaking, a vitamin is a substance that has to be obtained from the diet because the organism involved is unable to manufacture, or synthesise, it in its body. For example, vitamin C or ascorbic acid is a vitamin for people but not for horses. Horses synthesise this substance in their guts; people do not, and depend on a dietary supply. A trace element is, as its name suggests, a chemical element or nutrient that is required by the body in minute, or trace, amountsIt has long been known that dietary deficiencies can lead to illness (Wikipedia 2010a), although it was not until the early part of the 20th century that all the vitamins were isolated and described. It is also indisputable that until fairly recent times, vitamin and trace element deficiencies were common in humans even in the developed countries, and in less fortunate parts of the world this is still so.

The discovery of vitamins, and the ability to manufacture them commercially, soon led to a highly profitable industry selling supplements. Once the preserve of the whole-food shop, dazzling arrays of supplements are now de rigueur almost anywhere that food and, indeed, medicines are sold. The beliefs that routine supplementation is good for everyone, that most diets are deficient and that many people have special needs for extra micronutrients have all been promoted way beyond the actual evidence, to the point where many people not only take multivitamins routinely, but take them well in excess of the recommended daily doses. Unfortunately, recent studies are showing that when it comes to vitamins and trace elements it is possible to have too much of a good thing, and substances that are vital for health in small doses can be dangerous in larger amounts. This is hardly surprising: these substances are biologically active, and all biologically-active substances are likely to have side effects as well as main effects. For people living in developed countries, the scientific evidence at present is that there are no proven benefits to routine supplementation, that modern foodstuffs are not deficient in nutrients, that most people in industrialised countries can get all of their nutritional needs from food, and that high doses of vitamins probably do more harm than good (Hall 2008; Novella 2009; Skeptvet 2009, Carroll 2010).

Might this be the case also in horses?

Equine nutritional supplements have been something of a growth industry over the last 20 or 30 years. Your average tack shop or feed store now incorporates an impressive display of vitamins, minerals and other feed additives and there are hundreds of vitamin and mineral mixes sold for horses, even though the recommended daily allowances and maximum and minimum safe levels for horses are not at all well known (Merck 2008). In the last few months I’ve seen advertising that suggests that all soils, in the UK at least, are deficient in minerals, that all pasture and hay is therefore deficient, and that all horses therefore need to be given supplements. It is very difficult to find any hard evidence on this subject. In temperate climates there are localised areas of nutrient deficiencies in the soil, and these can affect the health and growth of ruminant livestock such as sheep and cattle depending on how intensively the land is managed (Whitehead 2000), but I’ve not been able to find any comparable data for horses that is independent and doesn’t come from somebody selling supplements. If any reader can point me to any, please do.

It appears that vitamin and mineral deficiencies in the horse are actually rather rare (Merck 2008) and generally follow some other problem such as starvation or malabsorption because of age or illness. Horses’ bodies manufacture vitamin A from beta-carotene and vitamin C from sucrose in the diet. All the B vitamins and vitamin K are synthesised by the bacteria in the equine gut. Vitamin D is produced by the action of ultraviolet light on the horse’s skin. In fact the only vitamin needed by the horse that has to come from its diet is vitamin E (Kerrigan 1986). There are adequate levels of the essential trace elements in most pastures and hay for a horse doing light to moderate work, and not otherwise stressed (Wikipedia 2010c). A horse who has reasonable access to sunlight and green, growing pasture or sun-cured forage is unlikely to be deficient in any vitamins. Mineral deficiencies can arise, but these are rarely a consequence of the pasture a horse is in and more commonly a result of faulty feeding. The trace elements most likely to be deficient are calcium, phosphorus, copper, sodium chloride (salt) and selenium (Merck 2008).

It is more common for horse rations to contain an excess of certain nutrients, and this can lead to direct toxicity or to induced deficits of other minerals. Phosphorus, iron, copper, selenium and vitamin A are the substances most commonly fed to excess (Merck 2008).

In horses, the best-known example of a nutritional disorder is nutritional secondary hyperparathyroidism, also known as big-head disease or bran disease. It is caused by a diet containing too much phosphorus and too little calcium, and was prevalent in western Europe when many horses were fed large amounts of wheat bran. Although the link between bran in the diet, calcium deficiency and bone weakness was established by the veterinary surgeon Dr Varnell in 1860, the condition was still occasionally being diagnosed in the 1980s in horses fed excessive amounts of grain (Hintz 1987). It is still common in horses grazing certain tropical grasses, where chemicals called oxalates in the grasses combine with calcium so that it cannot be absorbed by the horse’s gut.

Selenium and vitamin E deficiencies have been considered as possible risk factors in horses prone to exertional rhabdomyolysis (tying up or azoturia) but the evidence is by no means unequivocal: if your horse suffers from this condition it is sensible to have a vet blood-test your horse and supplement, if necessary, under expert supervision. This is definitely not one to guess at yourself as even a slight excess of selenium can cause irreversible damage including loss of mane and tail hair and sloughing of the hooves (Merck 2008), and large overdoses can cause death (Wikipedia 2010b).

As for the known toxic and harmful effects of overdoses: vitamin A in excess can damage the bones and skin and cause developmental problems in unborn foals, and too much vitamin D can cause calcium to be laid down in the blood vessels, heart and soft tissues as well as bone weakness and weight loss. It can be fatal. Iodine toxicity, resulting in an enlarged thyroid gland (goitre) can occur in horses fed too much dried seaweed. Too much potassium can cause heart problems. Feeding magnesium to excess – possible if you give your horse a fortified diet and also a magnesium-based ‘calmer’ – may interfere with calcium absorption and lead to a deficiency of that mineral. Iron excess can interfere with the metabolism of copper. Too much copper can cause problems with the uptake of selenium and iron (Merck 2008).

Current veterinary advice is that a horse in light to moderate work who is fed a balanced diet with plenty of good-quality forage (including hay or haylage and decent grazing), who spends at least 4 hours a day outdoors in order to metabolise vitamin D from sunlight and who is not in extremely hard work is, if otherwise healthy, unlikely to need any supplementation except for common salt, sodium chloride, which may be given as a free-access lick or added to the feed (Merck 2008). There are, however, circumstances in which it is possible for a horse to suffer from deficiencies. The most obvious is the fat horse or pony who needs to be on a severely restricted diet in order to control his weight. He may not be getting enough food to fulfil his needs for vitamin precursors (the substances that are converted to vitamins in the digestive tract) or trace elements, especially if his diet is based on soaked or poor-quality forage. Phosphorus deficiency can occur in horses eating poor-quality forage and no grain. It leads to weakening of the bones and low-grade lameness, but the owner is likely to notice the horse eating soil or other non-foods before any clinical signs develop. Very old horses may need supplements to compensate for the reduced efficiency of their digestive processes. Horses kept permanently stabled or rugged may have vitamin D deficiency as a result of insufficient sunlight on the skin. Horses in very hard work that makes them sweat a lot will benefit from electrolyte supplements to compensate for the sodium and potassium lost in sweat. If they are also fed high-fat diets they may need extra vitamin E. Horses who are chronically stressed, or ill, may have higher than normal requirements for some vitamins and trace elements. Pregnant and lactating mares may need supplements too (Wikipedia 2010c).

If your horse does have a clinically significant deficiency, he might need a higher level of supplementation than he’d get in an all-purpose vitamin and mineral mix, so it is worth having a proper test and just giving him what he really needs. In fact, if you have any suspicion that your horse may have a vitamin or trace element deficiency, it is far better for your bank balance and his health and soundness to have him blood-tested, and to adjust his diet accordingly.

For obvious reasons, it is best to have this test done by your vet and not by a company who is selling supplements and who has a vested interest in finding a deficiency. Nutritional deficiencies are easily and inexpensively diagnosed using blood serum analysis and this is the only reliable way of doing it. I wouldn’t personally be tempted by alternative diagnostic techniques such as hair analysis (Barrett 2008) or applied kinesiology (Barrett 2009) as they haven’t been shown to work in independent tests and in many cases the person or company offering the technique is also selling supplements. Do-it-yourself diagnosis and treatment also has its risks. I have heard of owners giving their nervous horses magnesium and vitamin B supplements ‘because they are essential for the proper working of the nervous system’ – and so they are, but nervous behaviour isn’t necessarily the result of a disordered nervous system, and the horse may not actually be deficient in those substances. Even if these owners don’t cause any actual harm with their oversupplementation, they are spending money on products that will do no more than produce vitamin-rich and mineral-rich urine. There are cheaper ways to improve the nutritional status of your fields, if that is the problem.

In conclusion, though most horses are unlikely to need supplements, some may benefit from them. And if your horse is one of those who would benefit, it would seem most sensible and economical to find out what he actually needs, given that supplements cost money and that some are dangerous in large doses.

By Alison Averis

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References

Barrett S (2008). Commercial hair analysis: a cardinal sign of quackery. www.quackwatch.com/01QuackeryRelatedTopics/hair.html

Barrett s (2009). Applied Kinesiology: phony muscle testing for ‘allergies’ and ‘nutrient deficiencies’. www.quackwatch.com/01/QuackeryRelatedTopics/Tests/ak.html

Carroll R (2010). Vitamins. www.skepdic.com/vitacon.html

Hall, H (2008). Should I take a multivitamin? www.sciencebasedmedicine.org/?p=160

Hintz HF (1987). The nutrition and feeding of horses. In Veterinary notes for horse owners. Ed by P D Rossdale. 17th Edition. Stanley Paul, London.

Kerrigan, R (1986). Practical horse nutrition. Adelaide, Australia.

Merck & Co. inc. (2008) Nutrition: horses. www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/toc_182600.htm

Novella S (2009). Another negative study of vitamins. www.sciencebasedmedicine.org/?p=372

Skeptvet (2009). Orthomolecular medicinebig talk, little evidence, real risk. www.skeptvet.com/Blog/2009/08/orthomolecular-medicine-big-talk-little-evidence-real-risk/

Whitehead DC (2000). Nutrient elements in grassland. CABI Publishing, Wallingford.

Wikipedia (2010a). Vitamins www.en.wikipedia.org/wiki/vitamins

Wikipedia (2010b). Selenium. www.wikipedia.org/wiki/selenium

Wikipedia (2010c). Equine nutrition. www.en.wikipedia/wiki/Equine_nutrition