Photo: Anne M. Eberhardt

The senior horse population is, and has been, on the rise. But with increasing age comes the potential for health problems. So what are the best ways to ensure senior horses stay healthy all through their golden years?

Mary Rose Paradis, DVM, MS, Dipl. ACVIM, an associate professor in the Department of Clinical Sciences at Tufts, in N. Grafton, Mass., gave practitioners tips on how to maintain senior horses' health at the 2013 American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn.

"In the past 20 years, we appear to be seeing more horses over the age of 20 years in our hospital," Paradis said. "A small study indicated that from 1989 to 1999 we saw an almost sixfold increase in horses presenting with problems who were 20 years of age or older."

Paradis said that it can be difficult to determine if health problems seen in older horses are caused by age itself or by a disease process. Additionally, she said, "older horses have many of the same medical issues as young horses, but some conditions appear to increase with age."

She also noted that old horses appear to be more medicated than younger horses: "When owners were asked about the use of medications for chronic problems, 25% of old horses versus 6% of young horses were on regular medications," she said.

Nonetheless, "older horses can lead healthy lives into their 30s, particularly if care is taken to address the problems as soon as they're recognized," Paradis said. Thus, she recommends that aging horses should have annual or biannual veterinary geriatric assessments, which include:

  • A thorough physical examination, focusing on body condition, dental wear, appetite, hair coat abnormalities, musculoskeletal stiffness or lameness, ophthalmic abnormalities, and cardiac health;
  • Blood work, including a complete blood count, chemistry profile, adrenocorticotropic hormone levels, and insulin levels; and
  • A fecal egg count.

Then, Paradis described some common health conditions in horses over 20 years of age and how to best manage them.

Gastrointestinal and Dental Problems

Paradis said that, in one study, colic was the most common reason for senior horses to be evaluated at a referral center, and another study showed that gastrointestinal lesions were the most common reason for death in horses 15 years or older.

Dental disease, Paradis said, likely plays a significant role in the development of colic and choke in older horses. A British study showed that "95% of the horses more than 15 years of age had dental abnormalities," she continued. "This was often overlooked by owners who reported that only 10% of their old horses had dental disease, and an additional 15% of owners reported that their horses exhibited quidding (dropping) of hay."

To attempt to reduce the incidence dental disease and related gastrointestinal problems, owners and veterinarians should monitor horses' dental health regularly but proceed with caution when problems arise.

"Radial correction of severe dental disease may not be effective in improving the animal's ability to eat forage," Paradis said. Instead, she recommended shortening overgrown and sharp teeth carefully to improve the horse's comfort, and changing the horse's diet as necessary.

Body Condition, Weight Loss, and Nutrition

Although many people associate aging with weight loss, Paradis said one study's results showed that 68% of horses 20 years or older had a moderate or good body condition score and 28% of horses were considered fat or very fat, while only 4% had a poor or very poor score. Thus, the researchers concluded that obesity is typically a bigger concern for aging horses than weight loss.

Should an older horse start to lose body condition, however, she recommended a veterinarian perform a diagnostic work up, as they would with younger horses, to identify the problem. Horses lose weight as a result of either decreased caloric intake or increased caloric needs.

"The caloric decreased intake in the older animal might be caused by a lack of good-quality feed, poor appetite secondary to a debilitating disease, poor dentition, maldigestion, and malabsorption," she explained. "Reasons an older horse may have an increased utilization of calories may be related to environmental cold, increased level of exercise (which is less likely), and increased catabolism (the body's breakdown of complex molecules, such as protein and fat, to simpler compounds) secondary to a debilitating disease."

Once the veterinarian and owner identify the cause of weight loss, they can implement feeding adjustments with the goal of increasing body condition.

Moving forward, Paradis touched on feeding senior horses: "Essentially, when dealing with healthy older horses, their nutritional requirements may not differ from that of the younger adult." Thus, the diet should be based around forage with supplemental concentrates as needed.

Paradis said many senior horse feeds contain a variety of important components for the aged horse's diet, including:

  • Extruded ingredients to increase digestion;
  • Pre- and probiotics to increase digestive flora;
  • Higher fat concentrations to increase caloric intake;
  • Higher protein concentrations to help maintain or build muscle mass; and 
  • Amino acids to aid in muscle maintenance, hair coat quality, and hoof quality.

Because dental problems often preclude senior horses from properly consuming and digesting long-stem forage, like hay, Paradis said many senior feeds are advertised as complete—meaning they're designed to be fed without additional forage.

However, Paradis said, "often feeding the geriatric horse comes down to feeding whatever they will eat. Horses with poor dentition will have problems with hay and whole grains. Alternative forages include grass, hays with minimal stem, and soaked hay cubes or haylage."

Paradis cautioned that the challenges with feeding senior horses arise when the horse has health problems requiring a specialized diet. Horses with obesity, equine metabolic syndrome, and insulin resistance, for instance, have specialized dietary requirements; how to feed such horses was beyond the scope of Paradis' lecture, but additional information can be found on TheHorse.com.

If questions arise about feeding a particular senior horse, contact a veterinarian or equine nutritionist for advice.

Musculoskeletal Disorders

Next, Paradis turned her attention to musculoskeletal disorders in senior horses. She said these problems were the second most common presenting complaint in one study, and lameness causes included laminitis (most in association with pituitary pars intermedia dysfunction, or PPID) and degenerative disease.

Additionally, she said, older horses were significantly more likely to consume long-term medications to treat musculoskeletal pain than younger horses.

"It is hypothesized that earlier injury to joints, muscles, tendons, and ligaments set up the geriatric horse for progressive degenerative changes," she relayed.

Paradis offered the following recommendations for managing osteoarthritis-related and other musculoskeletal pain in older horses:

  • Provide non-steroidal anti-inflammatory drugs judiciously;
  • Increase mobility to reduce pain, and avoid stall rest;
  • Modify the horse's training program so to not overtax his body's abilities;
  • Work horses consistently, rather than infrequently or just on the weekends;
  • Consider adding a nutriceutical, such as glucosamine-chondroitin sulfate, which has been shown to improve lameness grades, flexion test scores, and increase stride length; and
  • Contemplate adding complementary therapies, such as acupuncture, chiropractic, or massage therapy, to the horse's health care regimen.

Respiratory Disorders

The third most common presenting complaint for geriatric horses was respiratory disease, Paradis said.

"Although recurrent airway obstruction (or RAO) or heaves is not restricted to old horses, age has also been determined to be a risk factor for RAO," Paradis said. In one study, 19% of older horses that were receiving medication were being treated for heaves, she noted.

RAO treatment centers on decreasing inflammation and bronchoconstriction (tightening of the airways), which can be accomplished via:

  • Reducing environmental allergens, such as dust;
  • Providing 24-hour turnout;
  • Eliminating hay—which can contain dust—from the horse's diet;
  • Improving ventilation if the horse must be stalled; and
  • Administering oral or inhaled corticosteroids and bronchodilators.

Other Health Concerns

Paradis said ophthalmic problems and neoplasia (tumors) are also common health problems for senior horses.

"Although not commonly reported by owners, in a study by Ireland et al., 94% of horses more than 15 years of age had at least one abnormality identified by external ocular and ophthalmologic examination by a veterinary investigator," Paradis said. The most common ocular problems identified in aging horses were vitreous (the gel that fills the eyeball between the lens and the retina) degeneration, senile retinopathy (age-related non-inflammatory damage to the retina), and cataracts.

When it comes to neoplasia, both squamous cell carcinoma (SCC) and melanoma incidence increase with age, Paradis said, which SCC being the most prevalent and melanomas mostly seen in grey horses.

"In one study of SCC, affected animals had a mean age of 16.5 years of age," she explained. SCC is most commonly seen in eye structures or in the genitals. If not caught early it can metastasize to the lymph nodes and result in more serious problems. Additionally, Paradis said that "approximately 80% of aged gray horses have evidence of external melanomas. These rarely metastasize, but in a study of central nervous system tumors, melanomas were the second most prevalent tumors and appear to be age-related."

End of Life Decisions

"The veterinarian is often asked when it is best to euthanize the older horse," Paradis said, despite the fact that this question doesn't have one, firm answer.

According to one study, the top six reasons for aged horse euthanasia were:

  • Lameness;
  • Colic;
  • Chronic illness;
  • Acute illness;
  • Laminitis; and
  • Bone fracture.

Factors that influenced euthanasia, she said, included a "hopeless" prognosis, veterinary advice, and poor quality of life.

Ultimately, the decision to euthanize a horse rests with the horse owner in consultation with their veterinarian and should be treated as an individual decision for each animal and situation.