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Osteochondritis Dissecans In The Thoroughbred Racehorse

Updated: Apr 19

OCD Graphic | Restore Equine Therapy
OCD Graphic | Restore Equine Therapy

Osteochondritis Dissecans are two words that seem disconcerting initially but are only a long title for a reasonably straightforward issue. The term ‘osteo’ refers to anything concerning bone, ‘chondritis’ describes inflammation of the cartilage, and the word 'dissecans' means ‘to separate.’ Bone and cartilage inflammation and separation sound like a daunting illness. Horses with this disease do not form cartilage properly as they grow, causing weak and irregular bone formation in the joints of their limbs. These irregular formations appear as bone or cartilage flaps that can stay attached or break off to float within the joint. The end result can lead to inflammation and the possibility of arthritis developing over time. 

Fortunately, osteochondritis dissecans, most often referred to as OCD, rarely manifests as anything more than a common and manageable developmental ailment, affecting the growing bones of young horses.  OCD is found in 5-25% of all horses (ACVS, 2020), and is widely seen in many different breeds, disciplines, and ages, but it seems to rile up the racing community the most. This begs the question of career success and longevity, and if the disease is something to be actively avoided in the racing industry. 

The source of this disease, interestingly enough, is often genetic. The gene is carried by most domesticated horses, whereas wild horses rarely suffer from the disease, if they develop it at all. This narrows the issue down to breeding practices, especially here in the United States. There is little doubt that Thoroughbreds are continuously bred to be bigger, stronger, and most importantly faster. They need to be impressive at a very young age to get them out of the auction ring as quickly and lucratively as possible. They are not bred for any form of longevity, hardiness, or genetic quality, so it is no surprise that diseases such as OCD continue to circulate through their bloodlines. As long as breeding practices continue as they have been, we will continue to see OCD in our young racehorses. According to Kentucky Equine Research (2013), “There has been little work done in the United States with regard to heredity, and no type of screening program has been developed for osteochondrosis in stallions and mares that will ensure freedom from [this] condition.” 

Some other causes of OCD in young horses include musculoskeletal stress and trauma, nutrition, mineral imbalance, and limited exercise. There is a long list of factors that predispose Thoroughbred racehorses to the condition. If a horse has not already inherited the disease through the misfortunes of genetics, the risk remains high, depending on the animal's daily care and upbringing. A large cause of OCD in foals is rapid growth and development due to excessive nutrition. With rapid growth, the bones of the limbs lay down cartilage too quickly, allowing no time for ossification, leading to small portions of the bone breaking off. In addition to this, stall confinement and limited movement also allow for the development of OCD, and it is no secret that racehorses spend the majority of their careers in a stall. Nearly everything about a racing Thoroughbred's lifestyle predisposes them to this disease. 

The truth about this condition is that it often resolves itself. Depending on the size and location of the lesion, it will have little to no effect on training and career performance. Any joint throughout the equine body is susceptible; however, it most commonly occurs in the fetlocks, hocks, stifles, or even between the cervical vertebrae (Carson, 2010). In a 2006 article by the Consignors and Commercial Breeders Association (CBA), Garrett O’Rourke, manager of Juddmonte Farms in Lexington, reveals, “We see the majority of OCDs starting in September of [the horses'] weanling year...most of [them] are gone by about April, and the horses are fine.” Tom Evans, owner of Trackside Farm in Versailles, adds, "One of the things we've found is that many of the OCDs just go away. We do very few surgeries on OCD lesions. We found that a lot of them improve over time and are not issues." 

Despite the non-critical nature of the disease itself, surgery is occasionally necessary to prevent lameness further down the road, in which case many will opt for arthroscopy.

Most commonly present in weanlings and yearlings, symptoms of OCD can manifest as lameness, inflammation, fluid swelling, and swollen or enlarged joints. Once a lesion becomes clinical, meaning it is producing evident signs of heat, inflammation, and lameness, there is little short of surgery that can ensure a sale and career for the affected horse. It is important to note that a visible lesion on a radiograph is not necessarily a surgery-worthy affair. It is standard to wait anywhere from 30 to 60 days to see if the problem has resolved itself and the misplaced cartilage has disappeared. 

In the previously mentioned CBA article (2006), veterinarian James Morehead offers some insight, We may x-ray, find a lucency, and in 30 or 60 days, it may be gone...when we take a spring set of x-rays and find a lucency, we commonly say, "Take another set in 60 days" of the spot in question, and then you know the progression, and you know whether the progression is toward resolving properly into bone or not. 

In rare cases, the disease can become fatal. “OCD involving the shoulder joint is probably the most debilitating type of OCD affecting horses” (McIlwraith, 2009). Affected stifle and humeroscapular joints are the most likely to lead to immobilization and euthanasia. 

OCD often induces hesitation in potential buyers, but history proves that many Thoroughbreds have raced successfully despite having possessed the condition.

Seth Hancock, president of Claiborne Farm, offers some interesting insight on the subject. He explains that in order to sell a yearling well, x-rays must be performed and any lesions must be removed, but he continues, "If they are going to the racing stable...we don't x-ray them. There are plenty of good horses out there with OCDs." He concludes with, "There's no telling how many good horses, stallions and broodmares, raced well and went to stud with OCDs, and nobody knew the difference" (CBA, 2006).

It's safe to say that many historically great athletes were never radiographed for OCD, and it is anyone's guess just how many runners made racing history unknowingly carrying the condition. Unbridled’s Song (1993), found to have a lesion in his ankle, went on to victory in the Florida Derby, Breeders’ Cup Juvenile, and Wood Memorial (CBA, 2006). Farda Amiga (1999), a book 1 filly at the Keeneland September sale, sold for only $45,000 due to OCD in both stifles. She went on to win the Kentucky Oaks, Alabama Stakes, and finished second in the Breeders’ Cup Distaff. Cajun Beat was a multiple Graded Stakes winner. He famously won the Breeders’ Cup Sprint after surgery for OCD in both stifles. These are only a few of many success stories, demonstrating that OCD is not a career-ending condition. 

Holistic, conservative, or therapeutic approaches to the treatment of OCD are essentially unheard of in the Thoroughbred racing scene. Within these industry limitations, there are two ways to approach the issue; either through preventative therapy or post-surgery rehabilitation. Countless modalities are available to aid in post-surgery recovery. Hydrotherapy, especially underwater treadmills, swimming pools, whirlpools, and saltwater spas are all prime choices in stimulating the body's natural healing processes. If arthroscopy has been performed, the goal is to reduce inflammation and pain while restoring normal mobility. Rehabilitation after injury or surgery, post-arthroscopic surgery, and reconditioning after a lay-up are just a few of the many indications for aquatic therapy (Adair, 2011). Post-surgery hydrotherapy will curb the inflammatory response, relieve pain, strengthen muscle fibers, and provide exercise and conditioning without undue stress on the compromised skeletal system. Meanwhile, preventative therapy could make all the difference in the 30 to 60-day period of observing OCD progression. Laser, TENS, and cryotherapy are ideal for reducing inflammation, providing an analgesic effect, and accelerating healing within the body. PEMF, vertical vibration plate therapy, and hydrotherapy are proven to aid in the healing and restoration of bone. These are only a few examples of the many holistic approaches available to prevent the need for drugs and surgery or to alternatively provide rehabilitation.

Research suggests that, although concerning, OCD is often nothing more than a temporary and manageable developmental issue in racing Thoroughbreds. Chronic cases are rare and unlikely, and the disease often resolves on its own, or with minimal surgery. Overall, OCD has little to no effect on Thoroughbred racehorse performance or longevity, and they can continue to succeed having possessed the condition.


Adair, H., III. (2011). Aquatic therapy for conditioning and treatment of tendon and ligament injuries. 

Retrieved from file:///home/chronos/u-8a4ed026f389fe7b3fd9385145c29ccaff 1dd 8ca/ MyFiles/Downloads/Hydrotherapy%20Article%20-%20Dr.%20Adair.PDF

American College of Veterinary Surgeons. (2020). Osteochondritis dissecans (OCD) in horses. 

Carson, D. M. (2010). Osteochondrosis (OCD) in horses. 

Retrieved from m/know-your-pet/osteochondrosis-ocd-in-horses


Consignors and Commercial Breeders Association. (2006). OCDs in sale horses. 

Kentucky Equine Research. (2013, July 8). Possible causative factors of osteochondrosis in horses. 

McIlwraith, C. W. (2009). Update on bone disease: the impact of skeletal disease on athletic performance. 

Retrieved from 1.513.9969&rep=rep1&type=pdf 

The Horse. (2020, May 18). Equine OCD: harmless bone lesion or permanent problem. 

Retrieved from -les ion-or-per manent-problem/

Restore Equine Therapy
Restore Equine Therapy

Senya Sitzman

Founder and Business Owner of Restore Equine Therapy

Restore Equine Therapy is an equine bodywork provider primarily serving Northern Kentucky and Ohio. Restore aims to answer the lifelong question of how to best care for horses and give back a portion of what they provide us daily.


Senya Sitzman, founder and owner, has dedicated over 15 years to studying all aspects of horses. She possesses a degree in equine rehabilitation from Midway University in Kentucky, bringing a deep passion and understanding of equine anatomy and physiology, as well as a total commitment to each horse's holistic well-being. 


Restore prioritizes a hands-on approach to ensure that each session is tailored to the unique needs of your horse. The goal is to gain a strong understanding of your horse as an individual, building a foundation for continuous and measurable improvement. A healthy horse is a team effort, and Senya will collaborate with all members of your preferred team to deliver the best possible care.


You can learn more about Restore Equine Therapy here:



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