I read earlier in the week that arthritis is the highest cause of insurance claims in horses, which led me to thinking about the types of arthritis, and then from there onto degenerative arthritis.
We spent a lot of time studying conformation at college and faults to look for when critiquing a horse. Two main arthritic conditions I remember clearly are ringbone and sidebone.
Ringbone is excess ossification of the coffin or pastern joint, usually spreading to encircle the joint, hence it’s name ringbone. It can be either high ringbone, occurring between the large pastern bone and the short pastern bone, or low ringbone which occurs at the bottom of the short pastern bone and the upper part of the coffin bone. The extra growth usually hinders flexion of the joint, causing mild lameness but complications can arise if tendons get damaged as well.
You can usually feel high ringbone, but as low ringbone is in the hoof it can usually only be diagnosed with X rays.
Ringbone can be caused by strain or damage on the tendons causing the body to throw up new bone to help support and stabilise the affected joint. Trauma, or poor shoeing and conformation can also predispose ringbone to develop. If the surface of the joint is damaged then extra bone develops to immobilise the joint and reduce the inflammation and pain of the joint area.
If a horse has ringbone then their athletic ability will be hindered; ringbone that develops rapidly and nearer to the joints have a poorer prognosis. Treatment aims to delay the progression of ringbone; so correctional shoeing should support the heel and brings the roll over point back under the foot. Anti inflammmatory and steroid injections are also frequently used to reduce pain in the area and swelling so that the horse can continue with light ridden work.
Side bone on the other hand is very similar, but affects the coffin bone only. Usually affecting the front feet, it is diagnosed with X-ray but can be felt just above the coronet band.
Heavy horses, or those that do a lot of trotting on hard roads are more susceptible to developing side bone. As with ringbone, there is usually only mild lameness. It is treated with painkillers, injections and rest.
So whilst the development of side bone and ringbone doesn’t need to spell the end of their working life, regular check ups with the vet to monitor the progress, and then their workload may need to be adjusted to take into consideration the arthritis and the extent that the joint is changing.