Equine - Caring For The Aging Horse
Equine - Caring For The Aging Horse
Advances in veterinary medicine, nutrition, farrier science, and husbandry practices are all contributing to longer life spans for domestic horses. As a result, dealing with geriatric health issues is now becoming an increasingly common part of horse ownership. Three areas of special concern in the care of aging horses will be discussed here:
(1) maintaining healthy and functional teeth,
(2) detecting and treating degenerative joint disease (arthritis), and
(3) understanding Cushing's disease
Appropriate dental care is important at all stages of a horse's life. Unlike humans, whose teeth erupt and then stop growing, horses have teeth that erupt continually throughout their lives. Chewing wears the exposed surfaces of the teeth at a rate of 2-3mm/year until eventually each tooth exhausts its growth potential and falls out. The age at which a horse's teeth begin to expire is only partially predetermined by genetics; the useful lifespan of the mouth can be greatly prolonged by proper dentistry.
Sharp points on the edges of the molars must be smoothed to prevent painful ulcers from developing along the cheeks and tongue. Malocclusions (where gaps form between the upper and lower rows of teeth) need to be corrected so that the teeth contact each other to grind feed. These problems occur throughout life, and should be addressed in young and old horses alike. Other dental problems are more unique to the aging horse; for example, overgrowth of the incisors (front teeth) in relation to the molars, and loose or diseased teeth. Overgrown incisors may need to be shortened so that the molars will come into contact. Individual diseased teeth should be extracted to prevent infection from loosening adjacent healthy teeth, or penetrating into the sinuses.
It is best to have your horse's mouth examined at least once yearly to see if a float is needed. Regular exams are important because, by the time a horse shows signs of difficulty chewing, dental disease is usually quite advanced. The optimum situation is to keep all of the teeth in exact occlusion with frequent small adjustments. This insures effective mastication, which maximizes the availability of nutrients from roughage, while also helping to prevent choke and colic.
Interestingly, it is believed that the rate of tooth eruption in the horse is kept in check by appropriate pressure between opposing (upper and lower) teeth. This means that any tooth that is perpetually out of contact with an opposing tooth can actually begin to erupt more quickly than normal, using up its valuable reserve crown at a faster rate and reaching the end of its growth potential sooner. Therefore, regular floats that keep the rows of teeth level and in full contact actually keep the mouth younger for longer! Comfort, function, and the preservation of a youthful mouth...all are benefits of routine dentistry for your horse.
Another health concern in aging horses is arthritis, or degenerative joint disease (DJD). Genetics, conformation, athletic history and past injuries can all influence the development of DJD. When joints age, sustain injury, or are chronically subjected to abnormal biomechanical stress such as with poor conformation, the cartilage cushion in the joint can deteriorate. Cartilage is what provides 'shock absorption' between the bones that form a joint; if damage occurs beyond the body's capacity for repair, the function of the joint is compromised. Cartilage breakdown is accompanied by the release of enzymes that cause localized irritation. The same factors that degrade cartilage can also promote the formation of bone spurs (osteophytes) surrounding a joint. These bone irregularities might appear small on an X-ray, but they can cause significant inflammation, decreased flexibility, and pain.
Symptoms of DJD can include swelling of the affected joint, stiffness (loss of normal range of motion in a joint), lameness, and occasional clicking or popping noises with joint movement. DJD often affects multiple joints at once. Almost all aging horses develop some degree of arthritis. Commonly afflicted areas include the pasterns (ringbone), and the hocks (spavin). If you suspect your horse may be suffering from DJD, a veterinarian can assess the condition by palpating and flexing the joints, performing a lameness evaluation, and taking X-rays if necessary.
Treatment for DJD varies, depending on the degree of joint disease present. Horses with mild arthritis may benefit most from simply staying fit. Regular light exercise (for example, turnout with a compatible younger pasture mate) helps maintain joint flexibility and muscle condition, while preventing excessive weight gain. There are also many joint health supplements now available as feed additives for horses. Glucosamine hydrochloride and chondroitin sulfate are the main examples. These compounds are available under many different brand names. Glucosamine is a key building block for cartilage synthesis, while chondroitin inhibits cartilage breakdown. Together, they are useful in treating joint disease, and even more effective at preventing it.
For more advanced DJD, a variety of prescription treatments are available. Anti-inflammatory drugs can be prescribed to alleviate pain. Injectable products can be administered to increase the availability of hyaluronic acid, a component of normal joint fluid. Healthy joint fluid lubricates and nourishes cartilage, aiding in the repair process. In cases where DJD is very localized, it may be most effective to inject drugs such as steroids or pure hyaluronic acid directly into a painful joint. Speak with your veterinarian for more information on preventing and treating degenerative joint disease in your horse.
Finally, older horses are at an increased risk for developing a condition known as Cushings disease. This disease was once regarded as a rarity, but is now considered to be almost a normal part of the aging process in the horse. Equine Cushings results from a faulty interaction between two parts of the brain: the hypothalamus and the pituitary gland. First, the hypothalamus stops regulating pituitary growth. This allows the pituitary to undergo hyperplasia (excessive growth), and the enlarged pituitary then secretes abnormal levels of hormones. It is this hormone imbalance which causes the symptoms of Cushings disease.
Equine Cushing's disease has a wide variety of symptoms. Muscle wasting and abnormal fat deposition are common, resulting in a swaybacked, pot-bellied appearance. Suppression of the immune system causes prolonged wound healing and increased susceptibility to parasitism and infection. Increased water consumption (and urination) are likely to be noticed, especially if the horse is kept in a stall. One of the most striking changes sometimes associated with Cushing's disease is the appearance of an excessively long, often curly hair coat which does not shed out in warm weather. Finally, laminitis (founder) is probably the most life-threatening sequela of chronic pituitary dysfunction in the horse. A horse with Cushing's disease may show any combination of these symptoms, or none at all. However, an untreated case will nearly always progress to laminitis if enough time goes by.
A diagnosis of Cushing's disease may be obvious if the classical hair coat abnormalities are present. Horses in the early stages of the disease, however, may show nonspecific symptoms, so they must be evaluated using blood tests. If your horse is diagnosed with Cushing's disease, treatment begins with meticulous husbandry and may involve daily medication as well. Excellent nutrition, regular foot trims, frequent deworming, and attention to dental care are all very important. Aggressive antibiotic therapy may be necessary to resolve bacterial infections. Pergolide, a drug used to treat Parkinson's Disease in humans, can help to control pituitary overgrowth in horses. There is no cure for Cushing's disease, but proper care and medication can significantly improve the quality of life for affected animals, especially if treatment is begun early. Advanced cases involving immunosuppression and chronic recurrent laminitis are much more difficult to bring under control. Being familiar with this common, debilitating condition might some day prove important in your ability to provide excellent care for your geriatric horse.