Just like any type of mammal, the horse depends on the spine and skeleton to support the body, and the spinal chord and the brain to send impulses through the skeleton and muscles to move. In conditions that are known as degenerative disorders there are either toxins, injuries, infections, genetic conditions or other forms of diseases that cause the natural functioning of the skeleton or nervous systems to degenerate or break down over time. Once these conditions are present, unless noticed and treated very early on there is likely to be permanent and non-reversable damage that will affect the horse throughout his or her life, even if the condition is managed.
Most degenerative disorders of horses include conditions such as equine degenerative encephalomyelopathy, which is closely associated with the horse's inability to properly absorb Vitamin E. This condition is also genetically linked, with a complex series of factors often noted. The degeneration of the nervous system is most commonly seen with axons and neurons being destroyed throughout the spinal column. Foals may appear uncoordinated or may have poor control of their legs, most noticeably the hindquarters. Some foals with the condition can be managed with additional Vitamin E supplements however not all will respond.
Equine motor neuron disease is most commonly noted in Quarter Horses in the northeastern parts of the United States, but it is occasionally noted in other locations and with other breeds. This condition includes a degeneration of the motor neurons found in both the brain stem and the spinal cord, resulting in unwillingness to move, standing with the head low to the ground and the feet close together, often with constant weight shifting. This condition is progressive and non-inflammatory so it is often very hard to diagnose. It is most commonly seen in horses that are fed dry foods and grain rations and are not on pasture. In these horses a decrease in blood levels of Vitamin E is often noted, but supplementation does not always correct the problem. Occasionally these horses will seem to recover within a few months, but they are likely to go through periods of symptoms throughout their lives.
Arthritis is a condition of the joints and bones that becomes more progressive and degenerative as the horse ages or the joint becomes more damaged. Arthritis is most common in horses that have had an injury to a particular limb or joint when they were younger, or have a malformation of a joint from birth. Supplements and steroids may be used to treat the inflammation and pain associated with the arthritis and hydrotherapy may also be helpful to increase movement in the affected joint.
Degenerative joint disease in horses can range from mildly restrictive through to immobilizing the horse. This condition is most common in competition or working horses that have constantly or repetitively stressed joints. This constant trauma or injury to the joint results in bone chips, inflammation, irregular bone wear and thickening of the synovial membrane in the joint that provides fluid for easy movement. Heat treatments, hydrotherapy and pain management programs can be used to manage the inflammation and pain and surgery can be useful to correct bone chips and joint damage.