Bog spavin in horses with OCD of the tarsocrural joint is caused by what?

Bog spavin in horses with OCD of the tarsocrural joint is caused by what?

• A. Soft tissue swelling
• B. Infection
• C. Ligament rupture
• D. Effusion within the joint

Answer: (D)

Bog spavin is the distention of the tarsocrural (hock) joint capsule from an accumulation of excess synovial fluid—an intra-articular effusion. When OCD affects the tarsocrural joint, cartilage lesions and irritation provoke synovitis and increased production of synovial fluid, leading to a soft swelling over the hock that is actually fluid within the joint. This intra-articular effusion is the defining feature of bog spavin in this setting. Soft tissue swelling lies outside the joint capsule, infection would typically bring heat and systemic signs, and ligament rupture causes instability and severe pain rather than a primary joint effusion.

Bog spavin is the distention of the tarsocrural (hock) joint capsule from an accumulation of excess synovial fluid—an intra-articular effusion. When OCD affects the tarsocrural joint, cartilage lesions and irritation provoke synovitis and increased production of synovial fluid, leading to a soft swelling over the hock that is actually fluid within the joint. This intra-articular effusion is the defining feature of bog spavin in this setting. Soft tissue swelling lies outside the joint capsule, infection would typically bring heat and systemic signs, and ligament rupture causes instability and severe pain rather than a primary joint effusion.