With six bones articulating in close range and multiple tendons and ligaments controlling extension and flexion, the hock, or the horse equivalent of the human ankle, has many moving and shock-absorbing parts. Add to those the animal’s weight and the fact the joint is almost always in flexion, and you’ve got a recipe for a perplexing number of injuries. And, because each hock lameness case is as unique as the horse it beleaguers, it isn’t always easy to define the cause of the lameness, one veterinarian says.
Jerry Black, DVM, of Colorado State University, shared what he's learned about diagnosing unusual hock lameness cases at the 2013 American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn., by describing two scenarios he considers noteworthy.
Case 1: First, Black described a case involving a 2-year old Quarter Horse filly that suffered a kick-related injury to her right hock. The filly's attending veterinarians discovered mild soft tissue swelling and increased fluid within the hock joints, but they couldn't identify any specific injury on radiographs or ultrasound.
The filly's lameness worsened and her hock became more swollen by one month post-injury, so veterinarians opted to perform additional radiographs, on which they identified a chip fracture off the point of the hock. However, Black explained, such a chip fracture did not correlate well with the degree of lameness and swelling the horse exhibited. While chip fractures can cause lameness and some swelling, the filly's clinical signs were far more severe and progressive.
Source: TheHorse