What is OCD?
Osteochondrosis (osteochondrosis dissecans, also known as OCD) is a relatively common manifestation of a broader disease syndrome in horses, known as Developmental Orthopaedic Disease (DOD). The condition is recognised worldwide in young horses, across many breeds, typically developing within the first year post birth.
With this condition, the normal growth of cartilage and bone does not occur and abnormal loose flaps, or chips of articular cartilage or bone, form free-floating lesions within the joints of growing horses. This can lead to ongoing issues. The irregular cartilage may be thickened, soft, or weak, or can be separated entirely from the underlying bone. Current research suggests that the cartilage formation is abnormal in horses with the condition, leading to lesions.
Although the articular growth cartilage is predominantly affected, the metaphysis, which is the slightly flared portions of the bone, before the growth plate, can also be involved. When this happens, the cartilage, or growth plates do not mature into bone as normal and retention of this cartilage can then lead to OCD, or subchondral bone cysts.
While Osteochondrosis can occur in almost any joint, the most commonly affected joints include the stifle (lateral trochlear ridge of the femur), the tarsus (distal intermediate ridge of the tibia, lateral or medial trochlear ridges of the talus, medial malleolus) and the fetlock (distal dorsal midsagittal ridge of the third metacarpus/metatarsus). Less commonly, it can be seen to affect the hip, the elbow, or the cervical vertebrae. The disease is most commonly diagnosed by radiographs in young horses, often, even before any clinical signs become apparent. Another diagnostic imaging modality used to identify OCD is ultrasound; sometimes in combination with radiographs, or, in certain cases, OCD lesions are only diagnosed by an arthroscopic surgical procedure.
The condition is of particular interest, due to its potential to cause detrimental effects, such as joint effusion, pain and lameness in horses entering training, or during a pre-purchase exam, when preparing for yearling sales, for example. In fact, it is one of the top causes of poor performance and lameness in young sport horses.
Thankfully, the provision of a good quality balanced diet, along with careful management e.g. free access to pasture and less confinement, particularly during the first twenty-four months of life, can be protective to reducing, or even preventing the development of the condition entirely. These strategies provide the young horse with the best support structures for the development of healthy bones and joints.
Causes of OCD
Osteochondrosis has a multifactorial etiology, with many potential risk factors identified. These include the following:
- Rapid growth
- High carbohydrate diets (high glycaemic index feeds e.g. sugar and starch)
- Excessive levels play a part in altering energy metabolism and subsequently bone metabolism
- High calorie diets
- Mineral imbalances e.g. an imbalance of calcium and phosphorus, or excessive phosphorus with low calcium, or an insufficiency, or over supplementation of copper and zinc
- Genetic predisposition e.g. Warmblood, Thoroughbred, Arabian and Standardbred
- Blood circulation problems
- Biomechanical injury (trauma to cartilage)
- Lack of movement e.g. confined to a stable
- Excessive induced exercise
Management
The treatment for horses with OCD largely depends upon the severity of disease and the joints affected. Conservative management can be indicated and is in certain cases successful. This can include rest, or restricted exercise. The horse’s diet must also be addressed. A course of injections of polysulphated glucosaminoglycans (PSGAG’s), or hyaluronic acid, either intramuscularly, or intraarticularly, into the affected joint, may be prescribed. This can help to reduce inflammation within the joint. Non-steroidal anti-inflammatory drugs (NSAIDs) are not very successful for managing pain in OCD cases. Then for serious cases, surgical arthroscopy, under general anaesthetic, is required. Although arthroscopy can have positive surgical outcomes and is often curative, severe or lesions can lead to long-term debilitate consequences.
Prevention
Although OCD cannot always be prevented, the following management strategies are advised:
- Feed a diet of high fibre, low sugar and low starch
- Provide ad-lib good quality roughage (hay and pasture)
- Ensure that the diet is balanced, providing all the required vitamins and minerals, energy and protein. Copper, zinc, calcium, selenium and magnesium are of particular importance. Conversely, over supplementation will also predispose, so a very careful balance is vital.
- Provide every opportunity for turnout, which allows for abundant free exercise at pasture, for foals and young horses.
- Avoid excessive induced exercise, as this can result in damaged cartilage and joint injury
- Divide daily ration into 2 or 3 smaller feeds
- Remove uneaten portions between feeds
- Avoid overfeeding. Overweight foals are more prone to OCD, as well as other Developmental Orthopaedic Diseases (DODs)
- Provide unlimited fresh clean drinking water
- Weigh using a weight tape and adjust feedback accordingly, for growth and fitness rates
- Always increase workload before concentrates. Never the other way around
Conclusion
Although OCD is a common disease that affects young horses, there are many strategies that we can put in place, both to prevent and to treat the condition. Good management and nutrition are key; as is good vigilance. Where joint effusion, or
lameness is apparent, early intervention and a correct diagnosis, by a veterinary surgeon, is paramount for a good outcome.
References
Bazay, C. (2022). Ostechondritis Dissecans (OCD) in Horses: Causes, Treatment & Prevention | Mad Barn (Accessed: 4 November 2024).
Bourebaba, L., Röcken, M. and Marycz, K. (2019) ‘Osteochondritis dissecans (OCD) in Horses–Molecular Background of its Pathogenesis and Perspectives for Progenitor Stem Cell Therapy’ (Accessed: 4 November 2024).
Bourzac, C. et al. (2009) ‘Comparison of radiography and ultrasonography for the diagnosis of osteochondritis dissecans in the equine femoropatellar joint.’, Equine Veterinary Journal, 41(7), pp. 685–692 (Accessed: 4 November 2024).
Hilla, D. and Distl, O. (2013) ‘Heritabilities and genetic correlations between fetlock, hock and stifle osteochondrosis and fetlock osteochondral fragments in Hanoverian Warmblood horses.’, Journal of Animal Breeding and Genetics= Zeitschrift fur Tierzuchtung und Zuchtungsbiologie, 131(1), pp. 71–81 (Accessed: 4 November 2024).
Jeffcott, L.B. (1996) ‘Osteochondrosis—an international problem for the horse industry’, Journal of Equine Veterinary Science, 16(1), pp. 32–37. (Accessed: 4 November 2024).
Martinez-Saez, L., Marín-García, P. and Llobat, L. (2024) ‘Osteochondrosis in horses: a review of non-genetic and genetic factors associated.’ (Accessed: 4 November 2024).
McIlwraith, C.W. (2010) ‘Management of joint disease in the sport horse’, in 17th Kentucky Equine Research Nutrition Conference, pp. 26–27. (Accessed: 4 November 2024).
Ortved, K.F. (2017) ‘Surgical Management of Osteochondrosis in Foals’, The Veterinary Clinics of North America. Equine Practice, 33(2), pp. 379–396. (Accessed: 4 November 2024).
