The Old Gray Mare

In some ways, she's even better than she used to be, now that advances in geriatric equine medicine are helping horses live longer, healthier lives

an old horse

Strains of Tchaikovsky’s “Dance of the Sugar Plum Fairy” filled the stadium as all eyes turned to the handsome brown Dutch warmblood on the dressage ground below. For the next few minutes, spectators at the London Olympics watched as the horse, Parzival, seemed to float above the dusty ground, legs wrapped in tape like ballet slippers beating perfect time with the music. When the dust had settled, the horse and his 33-year-old rider, Adelinde Cornelissen, had achieved a new Olympic record for the Netherlands, and eventually, the silver medal in individual dressage.

It wasn’t surprising that Parzival did so well in the competition—he was the top-rated dressage horse going into the event. What was somewhat surprising was the equine athlete’s age: 15, the equivalent of 53 in human years.

More amazing still was the success of even older horses in the equestrian events at the 2012 Summer Olympics. Of the 50 horses that competed in dressage, a quarter of them were age 15 or older. The individual bronze winner, Mistral Hojris, was 17. Parzival’s partner on the bronze-winning Dutch team was 18. It was a similar story in the eventing competition, which combines dressage, cross-country and show jumping: two out of the three horses on Germany’s gold-medal-winning team were over 15, and one on the bronze-winning New Zealand team was 20.

New drugs, advanced surgical techniques and better nutrition and dental care are changing the very notion of what constitutes a senior horse.

When you consider that a human gymnast is generally past her prime at 16 and a basketball player is pushing retirement at 30, these equine athletes are treading on durable superstar territory. It’s all the more remarkable given that just a short time ago, 20 years was considered the limit for a horse’s life span.

“We used to say 20 was the end,” says Mary Rose Paradis, an equine veterinarian and associate professor of clinical sciences at the Cummings School of Veterinary Medicine. “A lot of times, owners wouldn’t spend any money on them after that. They’d retire them and let nature run its course.”

Within the last two decades, however, there has been a sea change in thinking about geriatric horses. Much like human medicine, equine medicine, including nutrition, dentistry and the treatment of diseases and conditions common in older horses, has vastly improved, to the point where horses are living well—and remaining healthy, active and even athletic—into their 20s, 30s and beyond.

Long-term Relationship

Horses’ long life spans make them very different from other companion animals, such as dogs and cats. “The oldest horse I ever treated was 51 years old,” says Nick Frank, a professor of large animal internal medicine and chair of the department of clinical sciences at Tufts. “That is a tremendous amount of time to spend with one animal.”

The longtime relationship between owners and their older horses can make them especially invested in their care, says Paradis, who specializes in newborn and geriatric horses—in part, for the same reason. “The thing that ties the two together is the bond that people have with them,” she says. “People become very attached to a newborn foal—but for older horses, you have owners who have owned them all of their lives.”

That is certainly the case for Anne Sobel, who was 12 years old when she met her horse O.P. (Ocean Paint), an American Paint Horse, 25 years ago. Now she is 37, and he is 31. “He is the love of my life, he really is,” she says. “I made a commitment when I was about 16 years old that we were in it for life. We have grown up together, and he’s absolutely part of my family.”

In the last few decades that enduring bond between older horses and their owners has translated into a renewed commitment to their care. Paradis and her student at the time, Margaret Brosnahan, V02, conducted a study of geriatric horses between 1989 and 1999 and found nearly a six-fold increase in the number of horses over age 20 that were coming to Tufts’ Hospital for Large Animals for care—a jump from 2.2 percent to 12.5 percent of the hospital’s total equine caseload.

Anecdotally, Paradis believes that number has continued to increase in the decade or so since that study. In a second study, Brosnahan and Paradis found that 10 percent of horses over the age of 20 were still used in competitions.

Probably the top reasons for the increase in the geriatric equine population are advances in nutrition and dentistry, which have helped combat such gastrointestinal disorders as colic, which Paradis and Brosnahan found was the primary cause of illness in elderly horses.

Another cause was musculoskeletal issues, most of which were degenerative and resulted in arthritis. The most specific condition affecting the older horse is a hormonal disease called PPID (pituitary pars intermedia dysfunction), better known as equine Cushing’s disease. Again, there have been significant improvements in detecting and treating PPID over the last decade.

Eat Well, Live Well

While better nutrition might not seem like a medical breakthrough, it has turned out to be important in increasing horses’ life spans—mostly because of dental problems. “The hypsodont teeth continue to grow out through a horse’s life, so by age 20, the roots are very shallow,” Paradis says. “By 30, horses are starting to lose teeth” and are unable to sufficiently grind their normal feed of grass and hay. Companies have started to make special food for senior horses in which the nutritional components are extruded into a softer feed, promoting better digestion.

Perhaps equally important are changes in caring for the teeth themselves. Horses are naturally adapted to dining on grass, which contains a small amount of silica that “polishes” teeth into even shapes. Domestic horses raised on hay or alfalfa, however, may experience uneven tooth wear, developing ridges and sharp points that can cause cheek lacerations and severe pain later in life.

If horses are exercised routinely, there is no reason that they cannot stay fit into old age.

For years, veterinarians used a tool called a hand float to rasp these irregularities, a laborious process that was not done often enough or well enough to reach all of the teeth. With the development of the power float, a drill-like tool with a diamond-headed grinder, veterinarians have been able to provide better care for teeth, especially the hard-to-reach back teeth, and extend a horse’s ability to chew comfortably.

“Dentistry has been the limiting step for some of these older horses,” says Frank. “If you combine advances in dentistry and advances in nutrition, you get rid of two of the major problems that are life-limiting for horses.”

Another problem that has struck down good horses late in life is lameness or other musculoskeletal problems caused by fractured bones or lesions in tendons. Here, too, there have been significant developments that have increased the chances an older horse will recover from such conditions.

For years, for example, veterinarians have been using steroids to reduce joint inflammation caused by arthritis or other maladies, but conventional wisdom was that using too many steroids could damage cartilage and weaken the joint over time. More recent studies, however, have shown that not all steroids are created equal. One in particular, triamcinolone, has been shown to actually protect joint cartilage when given in small doses.

“Historically, you say if you put too many steroids into a joint, you’d trash it,” says Jose Garcia-Lopez, an equine surgeon at Tufts, “but we have learned that certain steroids are better than others, and if you use them in low concentrations, they can have protective effects.”

Garcia-Lopez specializes in arthroscopic surgery, a minimally invasive technique that opens up a tiny keyhole in the joint through which veterinarians operate, using television monitors attached to cameras in their instruments to guide them. While the general techniques of the surgery haven’t changed (outside of using higher-definition TV monitors), Garcia-Lopez says that there has been a change in the willingness of surgeons to perform such procedures on older horses.

“Just because a horse is 22 or 23 doesn’t mean he won’t benefit from having his knee cleaned up,” he says. “If you have a fit horse, even if he is older and has an injury that can be repaired arthroscopically, you have a good chance of being able to return him to his previous level of fitness.”

Aiding that perception have been cutting-edge techniques that have helped horses in the healing process, using elements from their own bodies to speed recovery. In the last decade or so, veterinarians at Tufts and elsewhere have achieved success by extracting equine stem cells from bone marrow or fat, culturing them outside of the animal and then reinjecting them in places where the horse has suffered an injury. The regenerative properties in the stem cells help form new cells to bind the joint together.

More recently, vets have seen similar success using platelet-rich plasma (PRP), a substance derived from a horse’s own blood that is high in growth factors, which can interact with injured cells and spur tendons and ligaments to more quickly regenerate. “We’ve been using [PRP] in older guys with encouraging results,” says Garcia-Lopez.

Old and Active

In all of these cases, says Garcia-Lopez, the key to whether older horses benefit and recover from surgery is their overall level of fitness. When horses age, he says, it’s important that they remain active, even if it means just regular walks during the week. “You want to avoid that loss of conditioning,” he says. “If they have a prolonged period of time off, it’s much harder to regain that level of fitness again.”

If horses are exercised routinely, there is no reason that they cannot stay fit into old age. Sobel and her horse O.P. have gone trail-riding for years and still ride regularly three days a week, though they’ve cut back on their trail time.

Now, instead of riding for several hours, they’re out 45 minutes to an hour, and Sobel has learned to listen to her horse about when he is ready to head back to the barn. With small changes in food and blanketing at night, O.P. had been remarkably healthy until this past year, when he came down with several illnesses, including the hormonal disease PPID, which affects roughly one in seven horses over age 15.

With PPID, small tumors form on the pituitary gland, causing large amounts of hormones to be released into the bloodstream. PPID creates “many different changes throughout the horse’s body,” says Frank, a specialist in the disease.

Chief among the symptoms is accelerated hair growth, which can give horses an unnaturally thick, shaggy coat that refuses to shed out. Other symptoms can include excessive urination, fatigue, abscesses, infections and inflammation.

“The question is why does it happen in some horses, while others can go to 30 years of age with no problem?” Frank says.

Recent evidence has shown that obesity and insulin resistance predispose horses to Cushing’s disease by inducing oxidative stress that can accelerate tumor growth. One of the difficulties in treating the disease has been detecting it soon enough.

“The real challenge has been developing a test to diagnose it in the early stages,” says Frank, a pioneer in using a new thyrotropin-releasing hormone test to detect early-stage PPID. The test stimulates hormone production by the pituitary gland so that veterinarians can determine whether the gland is overly active or if there is a tumor.

Frank notes that recent research, some of which was conducted at Tufts, now allows veterinarians to screen horses for PPID by measuring the hormone ACTH in a single blood sample and comparing it to seasonal reference ranges.

The good news is that the drug pergolide can significantly slow the progression of PPID—if the disease is caught early enough. Pergolide was used to treat Parkinson’s disease in humans until 2007, when it was pulled for causing a small number of heart problems. Just within the past year, though, the FDA approved a new form of the drug for use in horses—a godsend for veterinarians treating the disease.

As PPID develops, Frank says, some horses develop laminitis, a painful inflammation of the hoof that can lead to lameness, “which is a really devastating disease that we want to do anything we can to prevent.”

New drugs, advanced surgical techniques and better nutrition and dental care are changing the very notion of what constitutes a senior horse. “I have really fought against this misperception that age is a disease and old horses should be written off,” says Frank. “I have a lot of admiration for these older horses. They become so smart and wily, and they know every trick in the book,” he says. “Those that survive into old age are the tough ones.”

That’s true of O.P., who overcame both impaction colic (essentially constipation) and peritonitis (an inflammation of the abdomen) this past year, despite warnings by his vet he might not survive. Now he is on medication for PPID, and Sobel plans on resuming their trail rides in the spring.

“He’s been called old for half his life now, but I don’t think he really grew up and matured until age 20,” she says. “There is this real wisdom in an older horse. When we go out riding, I don’t have to worry about training him or him being unpredictable. We just go out and enjoy the adventure together.”

This article first appeared in the Winter 2013 issue of Tufts Veterinary Medicine magazine.

Michael Blanding is a freelance writer in Brookline, Mass.


New Lease on Life for Older Horses

Older horses are great animals for many reasons—they’re smart, generally even-tempered and often trained in special skills such as jumping, polo or dressage. But as they age, the special care they require can get expensive.

Because horses inhabit a gray area between companion animals and work animals, they are vulnerable to being abandoned or given up to a shelter when an owner believes the animal has outlived its usefulness.

“Some people have horses all of their lives, use them for competition or pleasure and then when they can no longer do the job, they keep them anyway,” says Mary A. Koncel, a clinical instructor at the Center for Animals and Public Policy at the Cummings School of Veterinary Medicine. “There are other folks who get into horses, but it’s more of a passing interest. After five or 10 years, they decide they no longer want them.”

In the United States, more than 100,000 horses have been abandoned or are homeless. As the economy has slumped and feed prices have risen, shelters have become full to bursting. Other horses are simply let go to roam the plains out West. “It’s a horrible mess of bad consequences,” Colorado State University animal sciences professor Temple Grandin told Time magazine. “People are turning them loose because of the decline in discretionary spending.”

For her master’s degree in animals and public policy at Tufts, Koncel conducted a study on the adoption of wild horses in New England, collecting demographic information and assessing other factors that might contribute to successful adoption. In addition to continuing that research, she’s also trying to raise awareness about the plight of older horses that may be in great health but in need of a home.

One option, leasing, can be a win-win. An owner receives extra income to care for the animal, while the lessee can enjoy the animal for a period of time without the responsibility of taking care of it for life. “It can be a good thing sometimes to say, Look, instead of buying a horse for your kid that he or she is only going to ride three or four years, think about leasing one,” says Koncel.

In several states, equine welfare councils have been established to bring together the horse community to help people take care of their animals as well as find homes for horses in need of one. Koncel is working with community members and others at Tufts to establish the Massachusetts Equine Welfare Council to provide information on adopting and leasing older horses. (You can find the fledgling nonprofit on Facebook.)

Oftentimes, the gentler temperament of older horses makes them perfect first horses for younger riders. They can be good therapy horses as well, working with the disabled, at-risk youth or returning military veterans.

Horses with special skills can also be ideal for intermediate riders. “You can have a high-level dressage horse that can no longer do the more difficult movements,” Koncel says, “but could be leased out to a rider looking to move up in his or her skills and needing a horse with a little more talent.

“So many older horses have lots of miles on them; they have great minds, and they have wonderful temperaments,” she says. “The key is letting people know what the options are for good care. We hope the [Massachusetts] equine welfare council will be a clearinghouse for all of the resources available.”—Michael Blanding

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