Many veterinarians agree that 90% of equine lamenesses originate in the foot. But if it’s not in the foot, there are many other areas where lameness can hide. One area practitioners should examine if a horse is hind-limb lame is where the superficial digital flexor tendon (SDFT) attaches to the hock, suggests Sue Dyson, MA, Vet MB, PhD, DEO, FRCVS, head of clinical orthopaedics at the Animal Health Trust in Newmarket, U.K
“The SDFT has two broad ‘bands’ at the cap of the tendon where it passes over the back of the tarsus or hock,” she explained. “It is known that complete tears of one of those bands can cause a sudden, severe lameness.”
But what if one of those bands is just partially torn instead of completely? To find the answer, Dyson went back to basics measuring the length and width of the inner (medial) and outer (lateral) bands at the point of insertion in nonlame horses. She then examined the insertions using ultrasonography in a different group of nonlame horses to recognize what “normal” bands look like.
With this information in hand, Dyson subsequently diagnosed three sport horses with severe full-thickness, but incomplete, tears of the medial insertion of the SDFT on the calcaneus (a bone located on the back of the hock).