Developmental bone problems: A mini-glossary

To the left is a radiograph showing an OCD lesion. I think it is the thing owners of young horses fear most. When you read about developmental bone problems in young horses, a lot of terms are thrown around, and when I was first learning about it, the terms confused the heck out of me. Here is a little glossary, based on what I learned in several different articles and put into my own words...

The BIG THREE terms: from general to specific...
Developmental orthopedic disease (DOD) -- This is a broad and general term for muscoskeletal disorders/limb abnormalities, and covers a number of conditions: Osteochondrosis, contracted tendons, acquired angular limb deformities, ephysitis, subchondral bone cysts, flexural deformities, and juvenile osteoarthritis.

Osteochondrosis: This term is a subset of DOD, but still pretty vague. As part of the growth process, the bones of a young horse convert from cartilage to bone. Osteochondrosis is any interruption of the process by which cartilage hardens into bone,

Osteochondritis dissecans (OCD) : Now we're talking. When the normal conversion from cartilage to bone is interrupted or proceeds abnormally, some areas do not fully convert to bone. There may be a lesion or weakened area on the bone/joint--either cartilage or a mixture of cartilage/bone. The weakened area may break away from the bone or partially break away, forming a flap. This can cause swelling and pain/lameness. The term for this condition is OCD.

I hope to write more on practical things related to bone development--like what specifically to focus to ensure normal bone development in your young horse--stay tuned.