Ostoechondritis known as ‘OCD’
OCD is an abbreviation of the term Osteochondritis, which refers to inflammation and devitalisation of the joint cartilage overlaying bone in a joint. It is a form of developmental bone disease, often referred to in growing horses, which also have a high risk of the problem, as a form of Skeletal Developmental Problem, or DSP.
It typically occurs in young animals during their stage of rapid development, often fuelled by excess energy intake, a lack of adequate bone and trace-minerals and insufficient exercise.
Incidence
In young greyhounds, OCD is most common in the shoulder joints, but the stifle, hock and elbow joints may also be affected, which are similar to the predilection sites in rapidly growing young horses.
Large breeds of dogs are even more prone to developing OCD as compared to greyhounds, but the incidence can range from 2-10% in a group of young greyhounds.
It can occur in one or both shoulder joints, often becoming apparent during the schooling or track education period when a young greyhound’s limbs and joints are subjected to increased loading when galloping around bends on a track.
Underlying Causes
OCD has been related to a genetic predisposition in certain bloodlines of greyhounds, with large, rapidly growing and well developed 3-9 month old male saplings having 2-3 times the risk as compared to bitches.
Over the years, I have examined a number of litters of pups on high energy diets and with a relative deficiency of calcium and trace-minerals and all have signs and X-ray evidence of OCD.
The cartilage layer overlaying the bone within the joint appears to grow more quickly and outstrip its nutrient supply from the joint fluid or underlying bone.
It fails to mature and be able to withstand compression from overload exercise.
Cartilage does not have its own blood or nerve supply, and once it deteriorates, it can separate from the underlying (subchondral) bone cap, to form a ‘floating’ flap of diseased and dying cartilage.
This is referred to as Osteochondritis dissicans – referring to the separation of a layer of cartilage from the underlying vascular and sensitive bone.
The extreme nerve sensitivity in the underlying bone, and possible poor blood supply due to rapid growth in larger greyhound saplings, results in ‘bone to bone’ contact across the joint and the characteristic lameness of OCD.
Clinical Signs
As mentioned above, the lameness of OCD can be evident when a sapling is encouraged to gallop in a large yard, twists, turns or stops suddenly.
However, in most cases, the lameness is manifested during schooling and breaking-in to the lure, with sudden overloading of the devitalised joint surfaces in the upper limb joints when cornering or pulling up after a gallop.
In very early cases, twisting and extending the affected joint(s) will usually cause discomfort, particularly if the greyhound is trotted off on the lead immediately after the diseased joint is manipulated.
As the cartilage deterior-ates, the joint may begin to become soft and ‘puffy’ due to the accumulation of inflammatory fluid.
Usually a stifle joint, if OCD is developing, will be swollen and painful to touch.
An X-ray of the suspect joint is helpful to determine the degree of cartilage change and whether it is a simple OCD lesion, or an OCD with a detached cartilage flap.
Occasionally, a greyhound will exhibit only minor cartilage changes, but be clinically lame when walking.
This usually indicates an early stage of OCD with a risk of deterioration within 2-3 weeks into OCD with a cartilage flap if excessive weight bearing exercise is continued, such as during education on the lure.
Management
If the greyhound has a history of lameness and X-ray changes, then surgery to remove the diseased, dying and possibly partly detached cartilage is required, particularly if a flap is large and there is evidence of direct ‘bone to bone’ contact within the joint.
In this case, arthroscopic removal of the cartilage may be necessary to avoid the inflammation and ongoing damage that continues to devitalise the surrounding cartilage to expose the underlying bone.
Over the last decade, many new post-operative prepar-ations, including injectable hyaluronic acid and pentosan polysulfate, as well as oral glucosamine and chondroitin based joint preparations are available to assist joint cartilage repair in early cases or following surgery to remove the detached flap of cartilage within the joint.
If there are only minor X-ray changes, then in the feed joint therapy alone can be effective in early cases and promote repair of the joint.
Joint cartilage does not regenerate, except where stem cell transplants are used.
Normally, it can only repair itself with scar tissue, which will usually help to protect the underlying, highly sensitive bone caps.
If the condition is recognised early, then there is up to an 80% chance of recovery during a 3-6 month rest period.
However, if more than one joint is affected, or the greyhound is too heavy and overgrown for its age.
Prevention
Although OCD can have a hereditary basis in certain bloodlines, in many cases, it is related to overgrowth and excessive energy intake without an adequate balance of calcium and provision of essential trace-minerals for cartilage development.
Inadequate exercise and excess body weight in a growing pup, often the ‘boss’ in a litter, combined with sudden high loading exercise during schooling of an otherwise confined young greyhound, can increase the risk as well.
The same condition occurs in young overgrown horses up to yearling age on diets containing too much energy (over 130% of needs) and low trace-mineral intake.
In greyhound pups, it is important to ensure a balanced diet without excess carbohydrate energy from grain based dry foods and an intake of calcium, phosphorus, copper, zinc and manganese in a well formulated supplement to help provide the balance of energy and nutrients required for a steady growth rate.
There are a number of well formulated dry foods now available for growing pups and saplings.
It is also important to provide facilities for growing pups to free, controlled amounts of exercise in a yard or long straight run after weaning, rather than confine them to kennels and small yards for fear of injuring themselves.
If you notice any restriction in gait or favouring a limb by not extending it to the same degree as compared with the opposite limb, then you should have the greyhound checked for early OCD by your vet.
Once the cartilage is devitalized or begins to detach, then it is much more difficult to manage without surgical treatment.
