Osteochondrosis
Basic Information 
Definition
• General term used to describe a disorder of bone and cartilage of an unspecified etiology
• Developmental disorder of endochondral ossification
• Osteochondritis dissecans (OCD) is used to describe developmental or traumatic lesions of articular cartilage and subchondral bone
• Typically, it is identified as a detached fragment or flap of abnormal cartilage or cartilage and bone from the surrounding tissue
• Subchondral bone cysts (SBCs) are another manifestation of osteochondrosis, which can also be developmental or acquired.
Synonym(s)
Although the term OCD is not truly a synonym of osteochondrosis, it is thought of as one by many.
Epidemiology
Genetics and Breed Predisposition
• Although certain genetic lines have been shown to have a high heritability of osteochondrosis lesions, a specific genetic defect responsible for alteration of endochondral ossification has not yet been identified.
• Any breed can be affected, but it is common or overrepresented in Standardbred, Thoroughbred, and Warmblood breeds.
Risk Factors
Clinical Presentation
Disease Forms/Subtypes
• Osteochondrosis shows very different clinical signs and physical findings based on the location.
• OCDs are bilateral in 45% to 60% of affected horses.
Distal, dorsal MC-3/MT-3 (along the proximal to distal aspect of the mid-sagittal ridge and the adjacent region of the medial or lateral condyles)*
• Cervical vertebral articular facets: One of the recognized causes of cervical vertebral instability or stenosis in young horses (“wobblers” disease)
