Oh, My Aching Back!

The longer you ignore your horse’s symptoms, the more difficult they will be to control.

Do you know someone who suffers from back pain? Those unlucky folks, the ones who constantly nurse a sore back, often wonder, “If I lift that, will it do my back in?” Rarely do we hear stories in which someone used to have back pain. Rather, for the unfortunate souls who have to deal with this ailment, it’s a life-long management endeavor.

Horses are no different. Equine back pain also has to be managed for life. Even if it improves for a while, inevitably, it flares up from time to time. For a small subset, back pain is debilitating and impedes or prevents performance.

If you have a back-sore horse, don’t despair! This two-part series will look at “everything backs” and help you make your horse comfortable. 

First, we need to discuss the back itself and how to pinpoint the problem, which we will discuss here, so we can get a diagnosis. Next month, we’ll move into the solutions: medicines, different therapies and management changes.

Let’s Talk Spines.The equine spine has between 50 and 54 vertebrae—the number varies, depending on breed and build—that articulate to make a bendable frame from which the axial (limb) bones and thorax (chest) hang. The vertebrae house the spinal cord, which is composed of millions of nerve fibers that join the brain to make up the central nervous system. The cord runs through a large central hole in each vertebra, much like a string runs through a row of beads.

From between the vertebrae extend spinal nerves, which receive sensory input from the body and transmit it to the central nervous system and send motor commands from the central nervous system back to the body.

Vertebrae are dense bones, many with facets (plate-like extensions) that join adjacent vertebrae to create stability. Because the spinal cord is essential to the functionality of the body, and because the spinal cord can’t regenerate after an injury, the body goes to great lengths to protect it.

Tense Back Muscles. Some of us may think backs overreact to stimuli, tensing dramatically and refuse to relax. Other muscles aren’t so sensitive, so why are back muscles so grouchy? 

Usually, if a back tenses up, it’s because of a problem with the underlying alignment of the spine. It’s easy to understand why, if you imagine the spinal cord running through the vertebrae similar to a string through a row of beads. 

If a bead gets out of alignment, you risk harming the string. If a vertebra moves out of alignment, it could damage spinal nerves, and, more critically, the spinal cord itself. 

To prevent that from happening, the muscles around that vertebra tense to prevent any further movement of the bone. Muscle tension can subside when the bone moves (or gets moved) back into place.

In some chronic cases of spinal misalignment, however, soft connective tissues and muscles will permanently “memorize” the altered position of the bone, making it more difficult to move it back. Horses often present with chronic muscle tension and pain because, unfortunately, alignment issues with the spine go unaddressed in early stages, setting the horse up for repeated bouts of spasm.

Pain and Posture. We know pain is the body’s way of protecting itself from further damage. (See January 2013.) Pain can limit the amount that we move our limbs and can make us carry our bodies in a different way.

Over time, postural adjustments the body makes to avoid pain can become lasting changes. Muscles won’t extend and contract fully, tendons and ligaments lose elasticity, and joints lose their range of motion. The phenomenon can cause a downward spiral, limiting mobility and athletic ability. Not to mention, changes in posture stress other parts of the body, creating new sources of pain. Get the picture?

The solutions, like all things equine, sound simple but they’re difficult to implement. The approach is three- pronged:

1) Find the source(s) of the pain

2) Address the problem(s) to eliminate the pain

3) Correct the posture.

Causes of Back Pain. Possible causes of back pain are endless, but the most frequent include:

Hock and/or stifle pain is one of the most common underlying etiologies to back pain. Yes, you heard it right! Many horses with arthritis in those joints (especially the hocks) will carry their leg in a manner that reduces the amount that their hind limb joints have to bend. Consequently, the epaxial muscles of the lower back become quite tense and sore. Generally, this pain comes from the lumbar and lumbosacral regions of the back, but can extend even further back on the haunches.

Most veterinarians are quite keen at spotting hock pain in horses and, in some cases, a simple flexion test of the joints can help illuminate issues in those joints. Sometimes radiographs are necessary, although many horses with “clean” hock radiographs still exhibit clinical (physical) signs of joint pain.

Kissing spines (also known as dorsal spinous impingement) is a condition in which the dorsal vertebral processes of the spinal column collide into one another, resulting in bone spurs and severe pain. One study showed that 40% of horses have one or more kissing spines, however, some horses were bothered by kissing spines while others showed no outward signs of pain or performance limitations.

Uneven hooves.Club-footed horses or horses with one high and one low heel often experience back pain in their withers and thoracic regions due to the uneven pressure and twist that occurs in the spine as a result of the imbalanced feet. Imagine if you wore a high heel on one foot and no shoe on the other. After a few days, it’s likely you’d have back pain from stem to stern. 

Conformation flaws. The most common are: long back, sway back, high withers, ewe neck and sickle hocks/post legs.

Lack of exercise. A horse who lives in a stall and can’t move much will become stiff and sore. We can identify with this through the well-known principle of physics, “Bodies in motion tend to stay in motion.” If you want to do an experiment, stand still on one spot for one full hour. How does your back and body feel? Now, imagine doing it 24/7! 

Standing on uneven surfaces can compromise posture and result in back soreness. Many horses, due to their habits and repeated cleanings, have a concave “dip” in the stall floor. If the horse stands on a dipped floor, his back can become sore. You may not even realize that your horse’s stall floor is uneven.

Fitness. Horses asked to perform beyond their physical capability often end up with sore backs, especially when horses are “legged up” after a long winter or brought back too aggressively from a lay-up or period of inactivity. Their muscles get sore, as ours do, from work for which they’re not conditioned.

Chronic injury or spinal misalignment can cause back soreness. Obviously. If the body has to keep muscles tense in order to protect the spinal cord and spinal nerves, it’s logical that the muscles will become sore over time. Sometimes injury can result in nerve damage or pain. Ligament and/or muscle damage can also occur anywhere along the back. If a horse twists wrong, slips and falls, crashes into a jump, or even lies down awkwardly, a soft tissue injury can occur. If the injury isn’t identified and treated early on, it can develop into a long-term debilitating ailment.

Spinal cord wind-up is a phenomenon in which bodies in chronic pain become hypersensitive to any physical stimuli. Humans with this condition report that the body assigns an inappropriate sensation to a given stimulus. For instance, a body with severe spinal cord wind-up perceives a simple touch as painful (See January 2013). 

Ill-fitting saddles and/or inadequate padding can also cause back soreness due to pressure points. Even uneven stirrups can cause problems. Usually the left stirrup is longer because we mount from the left hand side, suspending all of our weight on the left stirrup leather day after day. Over time, the leather lengthens (that’s why it’s a good idea to purposefully switch stirrup leather sides every time you clean your tack). For your horse’s back’s sake, use the highest mounting block you can safely use as often as possible.

Poor riding posture.  Have you ever ridden in front of a mirror or videotaped your ride? Many riders ride with a tilt and don’t realize it. Also, it’s not uncommon to see riders with one or both legs out in front of them. This creates excessive pressure on the thoracolumbar junction and the lumbar spine along with the longissimus dorsi muscles. Ouch!

Poor riding. Period. Some riders have a long way to go when it comes to being a balanced “centered” rider. Although it takes experience and time in the saddle, it is of the utmost importance that we don’t do it at the horse’s expense. Riders that post or sit behind the leg and pound down hard on the back are the worst offenders. (While rider weight can make a difference, too, a heavier rider who rides well can be less damaging than a lighter rider bouncing all over the place.)

Dental issues can influence back pain. Horses that are trying to avoid pain in their mouth may brace their neck to avoid giving into the bit, or may clench their jaw in a protective posture. In turn, this tightens the back, which could result in soreness over time.

Bottom Line. Back pain is huge, with virtually unlimited causes. Our table will help point you in the right direction when investigating possible causes, as finding the source of the pain must be done before you can apply therapy. Next month, we’ll discuss treatments for back issues. And, yes, they vary tremendously, too, so get your detective work done now. 

Article by Contributing Veterinary Editor Grant Miller DVM.