Spavin, or osteoarthritis of the lower hock joints to give the condition its proper name, is a diagnosis that horse owners dread. Bone spavin can affect one or both of the horse’s lower hock joints and often affects both legs. The hock is actually comprised of several joints with the most movement occurring in the uppermost. The two lower joints have relatively little movement although a high degree of force is transmitted through them.
The cause of spavin is not well understood although it is more prevalent in certain breeds suggesting a genetic predisposition. It is also thought that conformation and trauma might play a role. Age is not necessarily a factor and the disease can affect horses of all ages. In many horses spavin can be managed using low dosage bute to provide long-term pain relief although this depends on the degree of lameness present and the horse’s job of work.
I had a horse that developed spavins in both hocks as a six year old. I was inexperienced at the time and didn’t even notice a problem. He was never lame, probably because I worked him every day and he lived outside for much of the time so didn’t noticeably stiffen up. When I sold him at age 13, the vet who checked him over for the purchasers noted the spavins but said they were cold and fully formed so would not pose a problem. He was of the opinion that the horse had remained sound and the spavins never bothered him because he was kept in work.
Unfortunately though, spavins can compromise the movement of the hock joint in some horses and the resulting lameness can be career-ending.
Diagnosis of bone spavin
Some horses can develop spavins without becoming lame and the condition is only spotted latterly following X-rays for some unrelated condition. Once pain is triggered however, it is usually persistent and it’s important to establish that the lameness is sited in the hock and not somewhere else. Your vet will use nerve blocks (intra-articular anaesthesia) to isolate the site of lameness although this can give a false negative result if the disease is advanced. This is because a degree of the pain originates within the bones of the affected joints and this is unaffected by the local anaesthesia.
There a number of different X-ray changes seen in horses with spavin and it’s important to recognise these as they influence the horse’s likely response to treatment. In some cases, spurs of bone appear around the joints whereas others involve more destructive changes within the actual joints themselves. Loss of cartilage occurs which causes a narrowing of the joint space, with or without bone loss in adjacent areas. Horses affected in this way are usually lamer than others and are harder to treat successfully.
In some less common cases, the nerve blocks will eliminate the lameness although the hock X-rays appear normal. Some such cases respond well to a single intra-articular treatment and probably had some degree of soft tissue inflammation.
Spavins cannot be ‘cured’ but they can be managed, so don’t despair if your horse is diagnosed with this condition. If you are concerned that your horse may be showing signs of stiffness or lameness behind, always consult your vet for advice.
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