2938 Vet. Med. Basic Sciences Bldg.
2001 S. Lincoln Ave.
Urbana, Illinois 61802
By Linda March
University of Illinois
College of Veterinary Medicine
Developmental Orthopedic Disease (DOD) is the larger category that encompasses osteochondritis dissecans (OCD). Both have to do with bone abnormalities of young, growing horses.
"OCD is one aspect of a syndrome of degenerative joint disease, contracture of tendons, leg malalignment, and/or club feet. If the owner sees any one of these problems, the horse may be susceptible to the rest," says Dr. R.D. Scoggins, equine Extension veterinarian at the University of Illinois College of Veterinary Medicine at Urbana.
Normally, as an animal grows, the soft cartilage at the ends of long bones matures and remodels to become hard. With OCD the cartilage does not become hard and instead breaks down, causing lamenesses. This breakdown of cartilage can lead to joint erosion, lack of cartilage on the joint surface, fluid build-up in the joint, bone cysts, bone-to-bone contact and/or pain.
OCD affects young horses, generally those that will have a mature height of over 15 hands. Although it has been detected in some horses as young foals, it usually causes problems for the animal about the time they enter training.
There are many factors that contribute to this disease syndrome. The genetic predisposition for rapid growth seems to be one. When breeding, research the stallion's background for any history of affected offspring, especially if the horse's mature height will be over 15 hands high.
Correct mineral balance in the diet is also important. Dr. Scoggins stresses, "It is critical that the brood mare is fed a diet with the right mineral balance and energy requirement to give the foal a good start in life."
Early detection of the problem is key to an effective treatment. Watch for recurrent lameness, especially if it shifts from one leg to another. The shoulder, hock and stifle joints are frequently involved. Bog spavin (boggy hocks) or puffy joint effusion (fluid in the joint space) may also be a sign of OCD.
Your veterinarian can use contrast radiographs, nuclear scintigraphy, and/or endoscopy to help detect OCD lesions.
Some cases are candidates for surgery and some will respond to medical treatment. If you see lameness, joint swelling or possible leg malalignment, have your veterinarian check the horse.
Proper feeding of the young, growing horse can help prevent OCD. For example, the feed's copper content should be analyzed. Copper oxide is not absorbed by horses, while copper sulfate is more readily utilized by horses. Over-supplementation of minerals has also been linked to OCD lesions. If you need help with feed analysis, call your veterinarian, an equine nutritionist or your area Extension office.
Foals can be started on creep feed, but energy and protein levels must be kept in check. If the foal has to carry excess fat on its immature body frame, problems associated with OCD can occur.
"Growth spurts in the foal, as well as sick and malnourished youngsters significantly increase the risk for tendon contractures and abnormal long bone development," notes Dr. Scoggins.
OCD is primarily a disease of the young, although it may not show up in the animal until three to four years of age. Bone cysts will take a couple of years to manifest signs of increased frequency and severity of lameness.
If you have any questions about OCD, call your veterinarian.