During my recent visit to Keeneland for the November Breeding Stock sales, I looked at an enormous number of weanlings and picked up a free booklet entitled OCD’s in Sale Horses: Commentary by Industry Professionals, published by the Consignors and Commercial breeders Association, writes ERIC WARD.

It stated in big letters on the cover that “We now know that OCDs are developmental and that most disappear or don’t affect racing performance.” Intrigued, I read on.

(OCD: Osteochondritis Dissecans (OCD), a joint disorder particularly found in horses and reportedly a growing problem for racehorse trainers).

As it said on the cover, the content was very much geared towards advising potential buyers to be relatively unconcerned with OCD on x-ray reports. The booklet lists examples of successful horses that have had OCD in the past. We are told that, among others,  2002 US champion filly Farda Amiga had OCDs in both stifles (medial femoral condyle) and went on to win the Kentucky Oaks. The opinion of Mark Taylor of Taylor Made farm is that the OCD’s made her affordable to anyone with her sale price of 45,000$. However, it does not mention whether she was operated on (though, in my experience these types of OCD usually require surgery). It does say that 1997 horse of the year Favorite Trick was operated on, but does not state which type of OCD he had. And certainly, the booklet does not raise the question of whether these horses should be bred from. Should there be a rule, similar to the German stipulation for stallions to be clean of wind and free from parrot mouths?

An example of how an OCD fragment would look on a radiograph. (from acvs.org).

The booklet continues into a question and answer with Dr. Jeffrey Berk. He suggests that the significance of an OCD depends on the location of a lesion and says that most vet’s opinions of which and where are subjective with regard to experience. He says that vets need to assess the level of risk of all their findings – both radiographic and endoscopic – along with conformation. Fair enough. But there was no effort to address the whys and wherefores of OCD and how to reduce it’s occurance.

Various racing/breeding figures are then asked to give opinions on OCD. Seth Hancock (Claiborne Farm) says that: “If you go looking for them, you will find them, and there’s no telling how many good horses, stallions and broodmares went to stud and nobody knew the difference {before x-raying sales horses became standard practice in America}”. Well, maybe so, but do we now have more OCD because we x-ray more; or is it because the thoroughbred (especially in the US) has largely morphed from a homebred athlete into a publicly traded commodity?

As we learn more about epigenetics (the science of how genes are switched on or off during development), we can begin to question whether treating horses differently has triggered a fast-acting genetic change in some aspects. Potentially, this concept has great relevence to the research of Dr. Emmeline Hill in the area of OCD.

Interesting new research in the honey bee has shed light on a Histone Code – a series of marks on the histone protiens around which DNA is wrapped in order to fit into the nucleus of a cell. It is known to exist in humans and other complex organisms to control changes in cell development. This is significant, as bees can develop as queens, female workers or drones despite sharing a common DNA. The significance of these little chemical marks can be influenced by the environment and what they eat. If a bee larvae is going to be a queen, it is fed only royal jelly, while workers/drones are fed pollen or nectar. “If you turn genes on or off during development, you can have a worker or a queen,” said Dr. Paul Hurd of Queen Mary University of London, in a major boost to epigenetics. The new element of the honey bee’s make-up may help to explain why bees are so sensitive to environmental change. Isn’t it possible that similar circumstances affect horses?

Returning to the booklet, Dr. Robert Hunt (Hagyards Clinic) states that conformation and potential athleticism need to balanced against minor x-ray blemishes, particularly in the fetlock. This I can relate to, after my trip to Keeneland. However, at that November sale I saw an alarming number of foals with summer coats. Why? If one looks at a foal with a summer coat and a weak action, particularly in relation to the stifles/hocks, one can perhaps deduce that it may not have had the paddock mileage that it needs. If we then discover that there is a lucency on the medial femoral condyle of the stifle or a flake in a hock; are we still supposed to chalk it down to an insignificant passing phase and purchase the horse: at worst having to operate at some stage down the line? Or do we mark what a pity on our catalogue page and wonder what might have been if the horse had been raised and fed with it’s long-term athletic future in mind.

Dr. Hunt then refers to research carried out by Drs. McIlwraith, Bramlage and others, whose evidence suggests that most OCDs do not have an adverse effect on racing performance and that x-rays should not have the final call, except in a few instances such as cyst-like lesions in the joints or crushed hocks. Finally, Stephen Jackson of Bluegrass Equine Nutrition advises feeding to minimise occurance. This appears to be sound advice, but again, nobody addresses the fact that nowadays more and more people manage their young, growing athletes with monetary value and the salering as a priority, as opposed to long-term athletic soundness and durability.

The summary of the booklet was: vets being cautious and saying that they can fix a lot with surgery; trainers and consignors saying take the risk; managers saying it’s there and we must deal with it and a nutritionist saying feed to minimise it. But the overwhelming general message and purpose of the booklet seems to be to encourage people to keep buying – no matter what. Sadly, there seems to be little thought given to what we can do to breed tougher horses in the first place.

If one feeds and exercises youngstock properly, will all these mild/phase-related unclinical OCD’s cease to exist? Will we only be left with clinically apparent and perhaps genetic OCD’s which may require surgery? Furthermore, if OCD surgery is successful and the horse runs, should it be excluded from the breeding population? It is worth noting that some initial signs of serious OCD cysts are only diagnosable at the trot, so should we ask for sales foals to be trotted if one suspects weak action and/or has read a vet report of stifle/hock lucency?

Lots of questions! Are the answers unavailable to us, or can we apply observation, common sense and perhaps even legislation to minimise the reccurance of OCD in our breeding stock? Food for thought on the eve of the 2013 foaling season.

Read also: Dr McVeigh on OCD.