Bone spavin, arthritis of the lower joint of the hock, is common in horses. Once it starts, the horse’s body tends to respond by growing extra bone along the edges of the joint, in an effort to stop movement and relieve the inflammation. During this fusion, which can take years, the horse will be lame.
One of the most common therapies for the pain is the injection of corticosteroids into the joint. However, results are often disappointing.
A study from the University of Glascow Veterinary School looked at the response to steroid injection in 51 horses with hock arthritis. All horses had been examined by bone scan (nuclear scintigraphy) before they were treated. They found that horses with a diffuse pattern of nuclear uptake in the joint responded better to steroid injections than horses that had a well-localized area of uptake. They also found that repeating the injection did not produce any further changes in the horses.
A bone scan may help your vet determine the chances of steroid injections helping with bone-spavin pain.