By Christine Barakat

Lots of turnout and a healthy diet have kept this senior citizen in good condition.

Experts estimate that the life expectancy of a horse in this country is somewhere between 18 and 22 years. Of course, that's just an average; illness or accidents will claim some horses in their prime; many more will thrive well into their 20s.

Just how long an individual horse lives depends on a combination of genes, luck and lifestyle. You can't change a horse's pedigree--or his luck for that matter--but you do have control over how he lives.

Today, most horses live pretty well. For one thing, veterinary advances and technological progress have improved the overall quality of care. Plus, "horses are considered pets today more than ever," says Robert Magnus, DVM, of the Wisconsin Equine Clinic and Hospital in Oconomowoc, Wisc., noting that this phenomenon takes on new significance as the years pass. "There's an emotional component to ownership that leads us to pay closer attention to an older horse's health and be more willing to seek better-quality health care, even if the horse isn't as 'useful' as a younger one may be."

Yet you might wonder whether there's something in particular you can do to increase your horse's chances of living a long and happy life. The answer is "Yes," judging from one of the largest studies of older horses to date, which was completed at Tufts University in 2003.

For the project, Margaret Brosnahan, DVM, and Mary Rose Paradis, DVM, surveyed the owners of 218 horses between the ages of 20 and 40, and reviewed the records of 467 horses over the age of 20 that were admitted to the Tufts veterinary clinic between 1989 and 1999. Not surprisingly, the researchers found that colic was the most common health problem among the horses in the study, followed by musculoskeletal diseases, such as arthritis. The third infirmity seen frequently among the horses studied was heaves and other respiratory disorders.

How can you head off these and other problems? As in human health, there are no guarantees. But a few specific management practices can help horses avoid some of the most common ills of old age. "An individual horse's care has to be tailored for that horse, that owner and their specific situation," says Magnus. "But there are some aspects of care that are particularly important when it comes to helping a horse stay healthy in his older years."

1. Take Care of His Teeth
Dental problems can have far-reaching health implications: The inability to properly chew foods can result in malnutrition, weight loss and colic. "If I had to tell horse owners to do one thing for their horses to help them as they age, it would be to pay attention to their teeth," says Brosnahan. "Bad teeth can lead to a world of problems in any animal and particularly an older one."

As a horse chews grains and grass, his teeth continually wear down. By the age of 20, he may have worn away 1 1/2 inches of his 2 1/2-inch-long teeth. This wear isn't always even. Individual teeth can develop sharp points, and molars can become misaligned, making chewing painful or impossible for an older animal.

Poor mastication, in turn, puts a horse at greater risk of choke and colic as large pieces of food pass through an esophagus and gastrointestinal tract designed to process much smaller morsels. In extreme cases, old horses may be unable to chew hay enough to swallow it at all. Even if ingested, poorly chewed food can't be digested optimally. "Whenever I see an older horse that isn't holding his weight or just isn't thriving, I make it a point to look at his teeth," says Magnus.

Equine dental care need not be elaborate: Most horses require only annual checkups and floating to smooth uneven wear. But regular dental attention is critical, and this, says Brosnahan, is where many horse owners fall short. "Since you don't often see your horse's teeth, it's easy to forget about them, but neglect can lead to dental disease so severe that the situation literally can't be fixed," she says. "We can almost always improve things a bit, but in many cases it's impossible to return a badly neglected mouth to 'normal' and the horse is forever dealing with the problem."

2. Be Vigilant About Parasite Control
A comprehensive parasite-control program, initiated when a horse is young, is critical to long-term health. "Horses are living much longer these days than before," says Brosnahan. "And one of the reasons often cited is that we have such great parasite-control products available."

Damage from parasites is cumulative. Over the years, scars develop where larvae attach to tissues, narrowing portions of the gastrointestinal tract. "Long-standing damage from parasites can lead to serious problems, including deadly colic," says Magnus. "And the damage can't be reversed."