"Back problems can be performance-limiting in the horse due to pain and reduced range of motion and flexibility," reported Kent Allen, DVM, of Virginia Equine Imaging, as he presented on equine back pain at the 2010 American Association of Equine Practitioners Convention, held Dec. 4-8 in Baltimore Md.
Allen reminded the veterinarians in attendance that many myths circulate regarding cause and treatment of back pain. A common assumption is that back pain is due to hock lameness problems, while other blame is placed on poor saddle fit or behavioral issues. A common, yet fallacious approach to equine back pain is to rest the horse without forced exercise, which, as Allen pointed out, might exacerbate a back problem since rest contributes to muscle wasting of the epaxial muscles along the spine.
Allen agreed that a primary limb lameness that creates an asymmetrical gait can lead to secondary back muscle soreness. Yet, he also noted other causes of back pain: primary muscle or ligament soreness, spinous process impingement (kissing spines), degenerative arthritis of the articular facets between vertebrae, spondylosis (ossification, or bone formation, of vertebral joints), or fracture of bony structures in the spine.
He encouraged diligent pursuit of an accurate diagnosis through a comprehensive physical and lameness exam followed by appropriate diagnostic imaging. He stressed that back problems cannot always be predicted relative to conformation--horses with good conformation might develop problems, while those with less-than-ideal conformational characteristics might not. Visual inspection is important to ascertain physical changes related to atrophy, swelling, or asymmetrical alignment. The veterinarian should palpate each spinal vertebra and the epaxial muscles on each side of the spine to determine if bone and/or soft tissue are causing pain. A horse's degree of flexibility and back mobilization should be assessed. Then, the veterinarian should perform dynamic evaluation by watching the horse move on a straight line, in longeing circles, and under saddle. Allen has had excellent success using a 50-pound weighted surcingle that mimics the weight of a rider and allows observation for signs of discomfort during girthing up and while being longed. After carefully assessing these many parameters, the veterinarian might order radiographs and possibly nuclear scintigraphy (bone scan).
Treatment suggestions by Allen are multifold. The primary lameness problem must be addressed, and saddle fit must be corrected as necessary. Other options directed locally to the back include ultrasound-guided injection of articular and/or spinous processes, extracorporeal shock wave therapy for kissing spines, acupuncture, chiropractic, therapeutic ultrasound, and tiludronate therapy (which is not currently widely available in the United States for use on horses, although some veterinary practices have provisional licenses to use it). Pain control with mesotherapy blocks sensory pain fibers pulsing through the skin in the epaxial area; this can lengthen pain relief following shock wave therapy or corticosteroid injections.
A successful approach to back issues addresses pain control and spasm while keeping a horse active during the rehabilitation process--back muscles must be regained to achieve results. Allen noted that in his hands, 80% of back pain horses returned to their previous level of exercise when diagnosed properly and treated aggressively.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.