Osteochondritis dissecans (OCD) is an affliction, if left untreated, that can have long-term harmful effects on the young, growing horse as well as the performing or racing horse. OCD actually is a disease subset of osteochondrosis and is classified under the umbrella term of developmental orthopedic disease.

Osteochondrosis affects the joint cartilage and also involves the subchondral bone just beneath the cartilage surface. Thus, we are, in a sense, faced with discussion of osteochondrosis, osteochondritis dissecans, and subchondral bone cysts.

To do this, one must find a way through a labyrinth of knowledge and speculation. This requires the services of sophisticated guides. To help show the way through the maze, we call on three experts from Colorado State University who have carried out a great deal of research and have written and spoken extensively on the subject. They are C. Wayne McIlwraith, BVSc, PhD, Dipl. ACVS; Gayle W. Trotter, DVM, MS, Dipl. ACVS; and Gary Baxter, VMD, MS, Dipl. ACVS.

Much of the information they proffer was set forth in proceedings from a seminar conducted at CSU entitled, “Lameness in the Horse: An In-Depth Short Course for the Horseman.”

We also will interject along the way a variety of other information that research has brought to light. First, let’s allow our guides to start at the beginning with an explanation of the term developmental orthopedic disease that carries the acronym DOD.

McIlwraith tells us that the term developmental orthopedic disease was coined in 1986 to encompass all orthopedic problems seen in the growing foal. It came out of a blue ribbon panel sponsored by the American Quarter Horse Association. It is a term that encompasses all general growth disturbances of horses and is, therefore, non-specific.

Before getting into specifics about certai