Osteochondrosis in the horse. II. Pathology

Area of Science:

• Veterinary Pathology
• Equine Orthopedics
• Developmental Biology

Background:

• Osteochondritis dissecans (OCD) is a significant orthopedic condition in young horses.
• Previous research identified OCD as a cartilaginous disease in pigs and dogs.

Purpose of the Study:

• To investigate the pathology of osteochondritis dissecans in young foals and horses.
• To examine fetuses and young foals without clinical signs to understand early disease processes.

Main Methods:

• Pathological examination of clinical cases of OCD in horses.
• Histological analysis of joint cartilage and subchondral bone.
• Comparative analysis with findings in other species.

Main Results:

• OCD is primarily a disease of cartilage, featuring thickening, disturbed endochondral ossification, degeneration, and necrosis.
• Cracks in cartilage lead to flaps and loose bodies, sometimes involving subchondral bone fragments.
• Bilateral occurrence in joints and concurrent lesions in other sites indicate OCD is a manifestation of generalized osteochondrosis.

Conclusions:

• Osteochondritis dissecans in horses is fundamentally a cartilaginous pathology.
• The disease process involves cartilage degeneration and potential bone involvement, differing from findings in pigs and dogs.
• OCD's presentation suggests a systemic condition, osteochondrosis, affecting multiple skeletal sites.