Some horses, especially those that have a longer body or more crest or arch to their neck will occasionally develop problems with bending and movement of the spine as they get older or if they are injured in some way. Just like with people, the horse's spine is made up of a series of vertebrae that are cushioned with cartilage known as discs. The spinal cord runs through the center of the discs and vertebrae, sending impulses and nerve messages through to the various parts of the body to keep the horse moving. Unlike people, the horse's spine is not really flexible except in the neck region and where the spine and the hindquarters or pelvis come together, the rest is basically rigid and strong.
Often as horses get older either the discs between the vertebrae start to rupture or slip, or the vertebrae themselves become out of alignment. This can lead to problems with the horse being able to move correctly, lift or lower his or her head, move from side to side, or even to coordinate leg movements. Typically the horse may not want to move or may be very sensitive to any pressure applied along the spine.
Often the first signs of a back problem include such changes in behavior as refusing to jump, canter or trot, uneven steps or gait, moving away from grooming on the back, swishing the tail repeatedly to show irritation when saddling or riding, bucking or refusing to be saddled, and mobility problems and a reluctance to lower the head to graze, feed or water. Since many of these problems may also be attributed to hoof or leg problems or even just poor behavior and attitude on the part of the horse often they are not checked until the back pain has become severe and the horse is not able to move or function normally.
When the spine is hurt or injured the long muscles that run down the length of the spine will often tighten to prevent the spine from moving or being further injured. This muscle tightening is known as spasms and is often very painful and debilitating to the horse. In addition the pressure from discs that are ruptured or inflamed can cause problems with the spinal cord, resulting in extreme pain and even immobility. Horses can also develop arthritis that can affect the ability of the spine to move and cause pain in riding and movement situations.
Vets can use a variety of tests to determine what the problem is with the spine. X-rays, flexation tests and even spinal blocks are used to try to locate the problem and then plan an effective treatment. In cases where there is swelling or inflammation or problems with arthritis steroids or non-steroid anti-inflammatories can be used, as well as pain management drugs and hydrotherapy. Hydrotherapy or exercise in water allows horses to strengthen their muscles around and along the spine while in water, relieving much of the pressure and stress.
Owners of older horses should be very observant of their horses and always have any back sensitivity or changes in behavior or movement checked by a vet to detect any problems as early as possible.