Damon O'Gan, DVM
“Back Pain” in the horse is a very broad topic, so this article will be limited to a brief discussion of thoracolumbar back pain. The thoracolumbar region is comprised of the vertebrae and surrounding soft tissues from the withers to the front of the croup region (approximately). The thoracolumbar region and sacroiliac region (roughly the croup area) are the two most affected regions of the back in performance horses.
The equine back is a large, complex structure, generally made up of bones, joints, and muscles. The bones (vertebrae) communicate with each other by two types of joints: the synovial intervertebral articulations (facet joints), which are true synovial joints, and the body joints, which include the fibrous intervertebral discs. Further support of the vertebral column is provided by the supraspinous and interspinous ligaments, and the dorsal and ventral longitudinal ligaments. Musculature consists of the epaxial group, the hypaxial group, the psoas major and minor muscles, and the rectus abdominus. By now you will probably agree with me that the equine back is a complex structure! Because of this inherent complexity, diagnosis and treatment of equine back pain can be difficult.
It is first important to differentiate between primary and secondary back pain. A large majority of the back pain cases I see are secondary. They are most commonly secondary to a hind limb lameness. The pain and altered gait caused by the hind limb lameness can result in an imbalanced back carriage, which often leads to back soreness. In most cases, the secondary back pain resolves quickly once the underlying problem is diagnosed and treated.
Primary back problems are much less common, but do occur and can lead to poor performance or even lameness. Let’s address the most common causes of back pain in the dressage horse specifically.
» Ill-fitting saddle: A good trainer, saddle-maker or veterinarian can help you assess your saddle fit. This should be ruled out before continuing on to more expensive diagnostic modalities.
» Rider imbalance: This is also an issue that should be addressed early on, before getting more in-depth medically.
Primary muscle spasm: Diagnosis is usually based on physical exam +/- ultrasound. This problem is often treated first with a combination of massage and systemic medication before proceeding to other diagnostics. Massage therapy can often be helpful, but due to the depth of much of the equine back musculature, some injuries are extremely difficult to affect with massage. The most common systemic treatment is a muscle relaxant, usually methocarbamol (Robaxin).
» Impingement of the dorsal spinous processes (kissing spines): The spinous processes are boney protrusions atop the vertebral bodies. For example, the withers are actually just the spinous processes of the forward thoracic vertebrae. Kissing spine lesions can occur anywhere between the withers and the croup. The spinous processes may get too close to one another, and begin to rub or to react by forming new bone. This impingement can often cause pain. Diagnosis can sometimes be made with ultrasound, though radiography and nuclear scintigraphy (bone scan) are often more beneficial. It is often necessary to perform diagnostic analgesia (blocking out) to confirm the kissing spines as the actual cause of pain. Some horses can develop kissing spines without suffering from any discomfort at all. Successful treatment can include direct injection of corticosteroids in the area of the lesion, extra corporeal shockwave therapy, or surgery in non-responsive cases.
» Osteoarthritis of the facet joints: Research has shown there can be eight types of arthritis in the facet joints. These can range from joint space asymmetry, to boney changes, to fractures. Again, ultrasound is sometimes helpful for diagnosis, but radiography and scintigraphy are often more beneficial. Treatment, as in arthritis of other joints, consists of joint injections (corticosteroid plus hyaluronic acid) and/or systemic joint support (Adequan and/or Legend). Rest is usually not very beneficial for these horses.
» Sacro-Iliac Disease: Unfortunately, this is another complex topic altogether, and cannot be addressed in this issue. If there is interest, perhaps in can be a topic in an upcoming issue.
Unlike humans or dogs, horses rarely experience problems with the intervertebral discs. It should be noted that complementary treatments are becoming more popular all the time. Acupuncture and chiropractic treatments are among the most common. Both modalities have shown positive results anecdotally for quite some time, but controlled scientific evidence has been lacking. There is much activity in this direction, however, and our understanding of these modalities continues to improve.
I would like to outline some simple training recommendations that can be used to help horses with back pain. Be sure your horse has been diagnosed and treated before continuing with training. It is important to realize that rest is usually not indicated in cases of back soreness, except those cases that are completely unresponsive to treatment. The goals of exercise management are to prevent further muscle atrophy and improve intervertebral stability.
:: Always check saddle fit.
:: Training must be progressive, especially for younger horses.
:: Be diligent about warming up; in sport horses, start at the walk, then progress to the canter before the trot. During the canter, the vertebral column goes through just one flexion/extension cycle per stride, while at the trot, the vertebral column experiences two cycles per stride.
:: Attempt to identify any movements that induce pain, and remove them from the regimen.
This has been a brief look at
equine back pain, and if it has prompted any questions, please feel
free to contact myself or Dr. Evans.
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