The Aging Horse

Old age is not a disease—it is strength and survivorship, triumph over all kinds of vicissitudes and disappointments, trials and illnesses. —Maggie Kuhn (1905-1995)

Owners of older horses have generally owned them for a long time. They have developed a bond that is similar to that seen with companion animals such as dogs and cats. Their desire to have their animals age gracefully with comfort and mobility has stimulated research in the field of equine geriatric medicine a field specializing in diseases as well as normal changes associated with aging. This article will highlight some of these areas to provide readers with a better understanding of the equine aging process and its associated changes.

Aging in itself is not a disease, but it can result in changes that predispose the body to disease. Horses age in different ways and at different speeds, depending on their genetics and environment. It is no different in humans. While there are numerous theories on aging, a widely accepted belief is that an organism’s biologic process is genetically determined at conception and lasts for the duration of its life. Environmental influences as well as stressors within the body (e.g., disease) can affect this process by either accelerating it or slowing it down (M. R. Paradis, Vet. Clin. Equine 18/3, 2002). This explains why some animals may appear old at the age of 15 years, while others may still be competing at the age of 25 years. Some humans seem old at age 60, while others continue working in their professions well into their 70s or 80s.

Association standards, a horse over 16 years old is considered aged. The oldest horses that have been studied have been mostly in their mid-40s, according to research cited in The Veterinary Clinics of North America (December 2002). Some people have tried to define the age of horses equivalent to the age of human beings. Using a mean lifespan for the horse of 25 years, researchers have suggested that this was equivalent to 71 years of age in people. Thus, a 20-year-old horse would be equivalent to a 57-year-old person and a 30-year-old horse would be equivalent to an 85-year-old person.

One of the most important ways to help our horses live as long and healthy a life as they are capable of is through regular, preventive medical care. Even if an animal is retired from regular work and is “out to pasture”, it should be examined by a veterinarian at least bi-annually and preferably more frequently (quarterly). A complete physical exam, including teeth, can reveal subtle changes in an animal’s health and allow for early intervention and possibly an improved outcome. It is well known that early intervention can be the single most important step in managing disease.

Between visits with a veterinarian, all older horses should be visually examined by their caretakers at least once a day, every day. Watch for changes in body condition, behavior and attitude. Regular assessments of an animal’s body condition, hair coat and general attitude can help determine whether there are any nutritional, endocrine or dental problems. Slight changes that are noted should be investigated immediately to determine whether there is a budding problem. Even seemingly minor problems that are addressed right away can make a big difference to the horse’s well-being.

Maintaining Proper Body Weight and Nutrition

The most common causes of weight loss in aged horses are failure to keep up with

deworming schedules, poor dentition, and/or debilitating diseases, according to Dr. Sarah Ralston of Rutgers Cooperative Research and Extension. She reports that horses over 20 years old had reduced digestion of fiber, protein and phosphorous compared with young horses fed the same diet, though many of the aged horses were still able to maintain good body condition on good-quality hay rations. Thus, the diet of older horses should be examined carefully and adjusted to an individual horse’s needs.

Older horses in particular need a high-quality diet — no dusty or moldy feeds. Also, older horses should be fed away from younger, more aggressive ones so they won’t have to compete for feed. More frequent feeding (two to three times a day) is better for the digestive system of older horses. Rations can be adjusted to maintain proper body condition, which generally consists of being able to feel the ribs but not see them.

Ample fresh, clean, lukewarm (not cold) water should be available at all times. Water that is too cold will result in reduced consumption, which can then lead to colic and other problems. Free access to fresh water will help reduce constipation or impaction problems, which tend to be most common in winter. If the horse does not drink well, feeding water-soaked feeds (1 to 2 gallons of water per feeding) will help increase fluid intake. Careful observance of water intake can help to avoid disastrous consequences.

Caring for Teeth

While all horses require regular tooth care, older horses and especially those known to have missing molars, should have their teeth checked at least twice a year. If chewing is difficult, “soups” of pelleted feeds may need to be fed. However, the feed should be chosen carefully, preferably under a veterinarian’s guidance, so that it contains adequate and complete nutrition. If the front incisors are missing or badly aligned, do not rely on pasture for nutrition. These horses must be fed complete feeds or loose hay and/or hay cubes since they cannot graze effectively.

Vaccinations and Deworming

Annual and bi-annual vaccinations for tetanus, sleeping sickness, and West Nile Virus is highly recommended for older horses, with additional vaccinations as indicated by the animal’s environment and herd mates.

A regular deworming schedule three to four times per year also is highly recommended. Intestinal worms can scar and cause chronic mucosal damage of the intestines or damage blood vessels, which affects nutrient absorption. Routine deworming should be an integral part of an older horse’s care.

Shelter and the Environment

Older horses are more sensitive to severe weather, both heat and cold, and often suffer weight loss when temperature fluctuations are extreme. It is essential that adequate shade is available in summer, and that shelter from wind and precipitation is provided in winter. Three-sided “run-in” sheds are adequate in most cases. Higher energy needs in winter can be met by providing increased feed in a more highly digestible form such as high-fat pelleted or extruded feeds.

Managing Age-Related Body Changes

In advanced age, it is not uncommon for horses to become reluctant to lie down due to difficulty in getting back up. This is especially true if they are confined to a stall where exercise and space are limited. While no studies have been conducted to determine how much “down time” a horse needs, most horses will lie down at least once every two or three days. If you suspect a problem, consult your veterinarian about ways to manage it. Pain can make a horse so miserable it may lose the desire to eat. The principal cause of pain in older horses is arthritis. The best thing to do for an arthritic horse is to allow it to exercise at will. Joints become stiff when a horse is kept in a stall for any length of time, and it is twice as painful to start moving again when turned out. Do not confine the horse to a stall unless absolutely necessary for medical reasons. The more the older horse can move about freely, the less stiff it will be. Ideally, there should be free access to a turnout, preferably with another compatible horse or pony for company.

Arthritic horses can be helped by anti-inflammatory drugs, chondroprotective feed additives, and other remedies. Attention to proper trimming and shoeing may help avoid unnecessary stresses on joints and can help keep the horse mobile. Also, maintaining an ideal body weight and avoiding obesity will prevent extra weight and stress on the joints.

Reducing Stress in the Older Horse

Finally, older horses do not handle changes in environment or routine well (see the Rule of More and Less in Director’s Message). A stable and consistent routine is needed for continued geriatric health, with as few changes as possible in exercise, feeding and travel. Relocating an older horse from one farm to another or even from one pasture to the next can be very stressful, especially if it means a change of pasture mates. Many do not adjust to a new group of pasture mates quickly and may experience detrimental weight loss during the adjustment period. Older horses tend to fall to the bottom of the pecking order and may not feel like fighting for food when an aggressive horse pushes them away. If hay or grain is group fed, careful observation of how well an older horse is getting to the feed may prevent a problem of detrimental weight loss before it happens.

UC Davis