What is curb?

• A. Dislocation of the tibia
• B. Fracture of navicular bone
• C. Sprain/tear of the plantar ligament
• D. Sprain of suspensory ligament

Answer: (C)

Curb is swelling at the back (caudal aspect) of the hock caused by an injury to the plantar ligaments that stabilize the joint. When these ligaments, especially the plantar ligaments that run along the bottom of the hock, are sprained or torn from overuse or trauma, the tissue thickens and forms a palpable, sometimes painful, swelling behind the joint. This makes the plantar ligaments the best fit for what curb represents.

The other conditions don’t describe this location or mechanism. A dislocation of the tibia would be a much more dramatic, acute joint disruption. A navicular bone fracture affects the hoof area rather than the hock’s plantar structures. A suspensory ligament sprain involves the suspensory apparatus more proximally in the leg and presents differently in timing and appearance of lameness.