Sometimes when an equine athlete’s performance isn’t meeting expectations, the problem area is relatively clear: an obvious gait irregularity, significant respiratory noise, or a persistently sore back. Other times determining what’s amiss is decidedly more challenging. Veterinary exams can range from a cursory physical exam to advanced imaging and uncover multiple abnormalities … some of which might be irrelevant to the decline in performance, one practitioner said at a recent veterinary meeting. So, how’s a veterinarian to approach such cases?

At the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California, Christiana Ober, DVM, MRCVS, reviewed how she evaluates poorly performing English sport horses. Ober specializes in treating and managing these horses at Andre Buthe Equine Clinic, in Marlborough, U.K., and is the New Zealand Three-Day Eventing Team’s head veterinarian.

“The ability to determine the cause of poor performance in the three-day eventing or English sport horse is greatly enhanced by a consistent, methodical approach to the examination and extensive knowledge of the discipline involved,” she said. “Additionally, an open mind, good communication with the rider or owner, and collaborating with other experts can improve the success rate of correct diagnosis.”

What is ‘Poor Performance’?

Ober said she begins exams by collecting a thorough history on the horse. “This should begin with a clear understanding of why the veterinarian was asked to examine the horse, making certain to clearly hear and understand the owner and/or trainer’s specific complaint.”

This might seem like an obvious first step, but one person’s definition of decreased performance might not align with another’s, she said.

“Poor performance can be defined as either 1) a recent deterioration in performance in a horse that was performing up to expectations or 2) inability to reach a desired or expected level of performance in an unproven horse,” she said. “The latter scenario can sometimes be more challenging for the veterinarian to assess given the greater potential for extrinsic variables, such as lack of talent or potential in the horse or management factors in the program.”

Veterinarians should also ascertain whether the patient has developed new undesirable behaviors, exercise intolerance, and/or injuries or diseases, she said.

The Physical Exam

After gathering a case history, Ober she palpates and observes the horse in an environment familiar to the animal prior to exercise or moving exams. These evaluations help identify subtle issues, such as swelling or behaviors indicative of pain, and allow her the ability to compare baseline findings to post-exercise results, she said.

She also listens to the horse’s heart and lungs to check for cardiovascular or respiratory issues that could contribute to poor performance.

Still, “the overwhelmingly most-common contributor to poor performance in the English sport horse is musculoskeletal pathology,” Ober said. Therefore, exams with the horse in motion and work are critical.

Her orthopedic exams include:

• Watching the horse move in a straight line at the walk and trot;
• Performing flexion tests;
• Longeing on soft and hard surfaces; and
• Conducting an under-tack exam.

Ober encouraged practitioners to complete the under-tack exam in the horse at his regular performance level, on appropriate footing, and with his usual rider and tack. As part of this assessment she evaluates:

• Saddle fit;
• The horse being tacked up, walked out of the barn or to the exam area, and mounted;
• How the patient warms up;
• Whether the saddle slips during work; and
• How well the horse recovers after exercise.

Her observations during the working exam drive the next steps.

If she sees an obvious lameness, diagnostic blocks combined with diagnostic imaging such as radiography or ultrasonography might be an appropriate next move.

Or, “full-body nuclear scintigraphy (bone scan) can be an additional useful tool in these work-ups when musculoskeletal causes are suspected or to assist in the work-up of multiple-limb lamenesses,” Ober said.

If the practitioner suspects low-grade musculoskeletal pain but doesn’t observe a significant unsoundness, a short course of non-steroidal anti-inflammatory drugs before a follow-up exam might be beneficial, she said. If the horse’s performance improves, chances are there’s a pain-related reason that still needs to be uncovered as opposed to another issue, such as a mechanical disruption or behavior problem.

Ober also said consulting with colleagues can help veterinarians reach a diagnosis or decide how to proceed with the evaluation.

Once the veterinarian makes a diagnosis, he or she can prescribe appropriate therapy.

Common Causes of Poor Performance

In a retrospective analysis of horses evaluated at her practice for poor performance, Ober said:

• 77% had a primary musculoskeletal cause;
• 18% had a primary internal medicine cause (such as respiratory, gastrointestinal cardiovascular, neurologic, or systemic issues); and
• 5% had a primary extrinsic cause (i.e., lack of horse talent, poor riding, or management problems).

“Any combination of those three groups is also a possibility that can lead to a very time-intensive and exhaustive examination,” she said. “It also goes without saying that the identification of an abnormality doesn’t have a linear relationship to poor performance”—so, just because the veterinarian finds something during an exam doesn’t mean it’s related to the performance problems.

“For example, identification of a heart murmur in an upper level event horse is unlikely to be a contributing factor to poor performance, although it should not be ignored completely,” she said

Take-Home Message

Determining why a horse isn’t performing up to expectations can be a time-consuming and tedious process. Ober encouraged attendees to approach such cases methodically and thoroughly.

“Although challenging, these cases can be exceptionally rewarding for both the client and the practitioner,” she said.