You’ve got to get under the horse’s skin, so to speak, to get to the root of back pain. While veterinarians traditionally believed back problems were usually secondary problems — such as caused by poor saddle fit or by compensating for lower-leg lameness — evidence is mounting that horses are plagued by a wide spectrum of problems originating from muscle and ligament strain in the back to arthritis and disc disease.
It makes sense when you think about it. After all, we’re aware of the causes of back pain in people, from simple strains to herniated discs to bone problems. However, for a long time, there was no way to diagnose specific types of back disease in horses, making it difficult for a veterinarian to confidently pinpoint a back problem.
Even postmortem examinations were unlikely to include back/spinal problems, since the area is encased in muscle and the spine would not be examined unless they were looking for a specific spinal problem.
One of the first recognized primary causes of back pain was dorsal impingement or “kissing vertebrae” — when the high spines on the tops of the vertebral bodies were touching and/or fused together. Typically found along the thoracic spine in the withers area and under the saddle, it was blamed on trauma or poor saddle fit and was easy to see on good X-rays.
It may also be found farther back along the spine, especially in jumpers where it may be related to the back flexion required by jumping and the impact on landing. We have since learned this finding may be only the tip of the iceberg, with more serious disease involving the discs or the vertebral bodies themselves.
In the last 15 years or so, both postmortem studies and the use of sophisticated diagnostic equipment have uncovered an incredible array of equine spine and pelvis problems.
Examining The Back
It’s not too difficult to tell your horse is back sore if he groans and sinks to his knees at the sight of a saddle, but back pain may give more subtle symptoms. The best way to learn what is abnormal is to understand what are normal reactions to an examination of the back.
If you run a capped ball-point pen with gentle pressure directly down the middle of the horse’s back, in the crease formed by the back muscles, the normal horse should dip slightly as you cross over the thoracic and lumbar regions (over the ribs and the flank). He should show little-to-no reaction up to the peak of the rump, then at the rear end, he should tuck under as you come down the slope of the rump toward the tail.
Indicators you’ve found pain — as opposed to the horse just being “touchy” — include: if the horse dips excessively, moves away, pins ears, kicks or swishes his tail.
Another symptom of pain is the horse that tenses up under the pressure and doesn’t dip slightly like a normal horse. This is especially true with pain that involves the more flexible portions of the spine — at the junction between the thoracic (rib) and lumbar (above the flank) vertebrae, back to where the lumbar vertebrae meet the sacral spine (junction of the flank and the rump).
Pain over and just behind the withers is best checked for by a gentle squeeze on either side of the midline.
Pain along the longissimus dorsi muscle, the long, round muscle that runs parallel to the spine on both sides, is a constant finding with back problems, whether they primarily involve this muscle or have another cause. To test for this, repeat the same sweep with a pen as above but over the muscles, 1 to 1?? inches off the midline.
Many diagnostic acupuncture points are located along these paired lines, at approximately one-inch intervals. When running the pen tip down the muscle, you may encounter one or more of these well-localized spots, no bigger than the pen tip, where the horse will obviously flinch or twitch on pressure.
Some are related to problems elsewhere on the body, but they also can signal trouble with the spine. In general, if you find only one or two well-defined spots, with no abnormal muscle responses, they may not be related to back trouble. However, if many sensitive spots are clustered together and the muscle reacts to the pen pressure by going into spasm or showing fine trembling movements that persist for several seconds or for as long as you hold the pressure, there’s a good chance you’re in an area of back pain.
With longstanding cases of back pain, the hind end musculature is often poorly developed and may contrast with better muscling of the forequarters. If the problem involves the sacroiliac joint or pelvis, it is often either one-sided or worse on one side than the other and loss of muscle will be more obvious on one side.
The horse may adopt unusual standing positions — whatever he finds most comfortable. He may prefer to stand with one hip dropped, a leg placed either farther under or farther behind, rotated inward or outward. He may also resist picking one or both legs up for cleaning the feet or farrier work.
Watching The Horse Move
How does the horse with back pain move' Very carefully!
Although obvious lameness may be nonexistent, the movement behind is generally stiff and with limited stride. The horse will resist or refuse to engage the hindquarters well. In early cases, particularly those involving instability at a vertebral joint, symptoms may come and go completely or always be low-level but subject to sudden worsening. The signs may occur when the horse is working and may mimic tying-up (see ”Case History” at end of story).
As time goes on, movement behind may become more restricted, usually with some degree of muscle loss, and the horse may actually begin dragging or scuffing his toes, sometimes confused with a neurological problem, such as EPM.
Lateral movement and bending is also often obviously affected. The horse will stiffen and brace himself against the leg you are attempting to get him to bend around, in effect pushing back against you. He may comply with your cues by a correct movement of the forehand but the hind is “locked.”
At the walk, the normal relaxed swing is lost and the feel is like perching on a fence post.
The trot may be his best gait but without the ability to engage behind for either extended or faster rates.
The canter is often rough and heavy on the forehand. The horse may refuse one lead entirely and be prone to cross-cantering.
Jumping is especially problematic because to do this correctly the horse needs to bend at the thoracolumbar junction. Takeoff close to the fence requires engagement and bending, causing pain and making the horse prefer to jump flat and from farther back. A good bascule also requires good bending through the spine.
With back pain, the horse will tend to drag the hind end along rather than flexing his legs well. If the problem is impingement of the dorsal spinous processes, the horse may be less free with using his neck for balance as raising the head causes the back to hollow, bringing these bones into closer apposition.
On turnout, horses with back pain want to buck and kick instinctively — a movement that can release the spine — but can’t or won’t because of the pain. They may begin to buck and kick, but the movement will be feeble and with a short range of motion, often more like a hop than the impressive, “letting loose” kick you will see from a normal horse.
Getting up and down, or rolling, may cause pain, making the horse slow and cautious, even avoiding it entirely. Even simple, everyday movements for a normal horse may be painful, such as putting the head up to eat out of a hay rack, putting the head down to graze or reaching back to scratch his side or bite at a fly.
Imaging techniques like bone scans, ultrasound — and likely CAT scans in the not-too-distant future — make it easier to localize back pain and get some idea of the nature of the problem. H owever, the technology is still not good enough and diagnosis often remains imprecise.
Even if the problems were better defined, horses still wouldn’t have the surgical options small animals and people have. However, even in other species surgery is a last resort. The first approach is always exercise, physical therapy and medication when needed.
Medication options are essentially the same as for arthritis, including aspirin, NSAIDs (like phenylbutazone or flunixin/Banamine) and herbal alternatives. We recommend reserving these options for times when symptoms are particularly severe. Muscle relaxants, like Robaxin, are also sometimes helpful in managing symptoms, especially during flare-ups when muscle spasm is a prominent feature.
Fortunately, many other therapies can make the back-sore horse more comfortable. Most are lumped by veterinarians under the heading of “alternative therapy” for horses, but they are pretty standard fare with human physical therapists.
Back pain should not be always dismissed as a secondary problem that will go away when something else is corrected. Specific “cures” for most of the causes are not an option.
Physical-therapy options — from heat to therapy devices and acupuncture — can provide the horse with significant pain relief, improving both his quality of life and his performance. We recommend these therapies as the first approach with medication only when necessary.