Diagnosis of Back and Sacroiliac Pain

Chris Ray, DVM, MS, Dipl. ACVS, of Weatherford, Texas struck off the discussion about lameness and performance problems associated with back and sacral area pain at the Western Performance Horse Forum held in Nampa, Idaho, on Feb. 15-17. He recommended the importance of listening to the trainer or owner, as many back problems only appear when a horse is performing his athletic activity.

Some horses are so sore they don't want to unload off the trailer. A veterinarian will perform a visual and palpation exam of the back. When a horse is asked to bend, his response is assessed as to whether there is a difference between directions. About 90% of the time, problems are found at the top of the sacrum along the midline.

Often a back-sore horse has other problems, making it difficult to separate poor performance from back pain or lameness. It helps for a veterinarian to assess a horse before problems crop up. The horse should be squared up to examine for symmetry. If the horse is put in a round pen, one might notice bracing through the hip and loin at a trot, and at lope or canter. A braced back rather than one that rises gently casts suspicion of a back problem. The horse might cross canter, and if asked for a sudden stop, might slap all four legs on the ground rather than making a nice, fluid stop.

When palpating the back, it is necessary to separate pain in the muscles from sore acupuncture points. To separate a "goosey" horse from one with real pain relies on relaxing the horse with gentle massage, starting at the withers. Slowly, as the hand moves back, a little pressure is made with the meat of the finger, not the nail. A sore-muscled horse usually yields and drops to pressure, whereas there is bracing and no aversive movement when affected by deeper soft tissue or bone pain.

Sometimes it is necessary to have the horse ridden to duplicate performance or lameness issues. Back pain might change a horse's attitude when the rider gets in the saddle. Some limb manipulations, such as pulling the hind limb outward, can cause the horse to object because of amplification of pain in the pelvic or lumbar region. A horse affected thusly moves off in a crouched position. In many cases, lameness problems in the stifle or hock will elicit secondary back pain due to changes in limb use. A neck problem, especially cervical arthritis, can also elicit a sore back because the neck is important as a balancing mechanism. Radiographs and nuclear scintigraphy are useful to image this area.

Specific back injuries include impingement of the dorsal spinous processes (kissing lesions) and fractures of the dorsal spinous processes. These are identified with nuclear scintigraphy to identify hot spots of inflammation and radiology to image the lesions.

Sacroiliac problems produce stiff movement, and sometimes lameness depending on location of the strain of the dorsal sacroiliac ligament at the top of the sacrum. Nuclear scintigraphy is helpful in making this diagnosis. The panelists agreed that most of the pathology is found in the back half of the sacroiliac joint. Many horses with hunters' bumps are not typically lame, with the enlargement developing over many months. Ultrasound is a useful tool for defining if there is a significant injury in the ligament.

Hip injury can induce back pain, so this should be evaluated. Hip problems or acetabular fractures are difficult to discern on scintigraphy because of the distance between the hip tissues and the gamma camera, so radiographs are best to view osteoarthritis in this region.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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