Traditionally, veterinarians performing lameness examinations have assessed horses’ gaits as they’re walked and trotted by a handler.
“We’ve spent years and textbooks watching horses in-hand, picking apart the head nod, the hip hike, the lame limb,” said Elizabeth Davidson, DVM, Dipl. ACVS, ACVSMR, associate professor of sports medicine at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, in Kennett Square.
And while this is a valuable gait assessment, it can be augmented by also evaluating the horse while it’s being ridden. Davidson described the importance of the ridden exam during the 2018 British Equine Veterinary Association Congress, held Sept. 12-15, in Birmingham, U.K.
A ridden lameness exam allows the veterinarian to watch the horse while doing its job and at other gaits besides the walk and trot.
“This is particularly true in sport horses when specific movements, sport-specific gaits, and changes of pace such as canter to trot transitions are not only training but competition elements of the horse’s performance,” said Davidson. “For these athletes, the role of the ridden lameness examination becomes an important diagnostic tool for the lameness detective.”
Signs of lameness under saddle can be extremely variable, she said, ranging from obvious limping to reluctance to go forward, being behind the bit, resisting the bridle, losing rhythm, bucking, rearing, head-shaking, and more.
“Many of these pain-related performance abnormalities are only apparent or exacerbated with a rider,” Davidson said.
This is because the horse-rider-tack dynamic changes the horse’s movement patterns and increases limb loading. The rising trot, for instance, is an asymmetrical gait, said Davidson, which produces uneven limb loading, uneven stresses on the back, and changes the mechanisms of the horse’s movement. So, too, do the sitting trot, two-point, circling, etc.
“If we’re clever, we can use this knowledge to assess and evaluate these hoses, such as posting on the other diagonal,” she said. “Minor changes can enhance our ability to evaluate the horse.”
The addition of the saddle can also cause signs of pain in ridden horses. Ill-fitting saddles, obviously, can cause back pain. And the saddle’s pressure only increases with speed, said Davidson. If the saddle slips to one side consistently, research has shown that hind-limb lameness might be to blame—most saddles slip to the side of the lame hind limb, she explained.
When performing lameness exams, Davidson recommended practitioners first get a baseline ridden assessment, then perform diagnostic analgesia (nerve blocks) and compare how the horse then performs under saddle to identify the problem area.
“Albeit time-consuming, nerve blocks should be performed in a systematic and thoughtful manner, since best guesses frequently result in improper diagnosis and treatment followed by continued poor performance,” she said.
Davidson emphasized that while the ridden exam is not a substitute for in-hand evaluations, it greatly enhances the veterinarian’s diagnostic picture.