Which condition is a spasmodic contraction of the lateral extensor tendon of the hind leg?

• A. Spavin
• B. Stringhalt
• C. Thoroughpin
• D. Quittor

Answer: (B)

Stringhalt describes a sudden, involuntary contraction of the lateral digital extensor muscle, causing the hind leg to lift with a high-stepping, jerky motion. The lateral extensor tendon on the outside of the hind leg is what drives that lifting action, so when it spasms, the limb repeatedly raises the toe. The other conditions involve different structures: spavin is a problem in the hock joints, thoroughpin is fluid buildup in the tarsal sheath, and quittor is an infection at the coronary band. So the spasmodic contraction of the lateral extensor tendon aligns with stringhalt.