Elderly Horse

Horses are now living longer lives than ever before, in part because more attention is paid to their health. However, like people, they experience some deterioration of their body systems as they age. Outlined in this article are some of the more common problems associated with elderly horses and some recommendations to help keep your aged companions healthy and sound.

Dental Problems

A horse’s teeth are vital to its health no matter what their age but the risk of dental issues increases as your horse gets older. Common signs of dental disease include excess salivation, difficulty chewing feed, dropping feed, choke (obstruction of feed in the esophagus) and
weight loss.

dental

Horse teeth are different than human teeth as they have a significant but finite reserve root. This reserve root replaces the crown that is worn away during mastication. The crown of horses’ teeth gradually wear as they grind against the opposing crown and abrasive feeds When there is no more root to replace the crown that is lost, the teeth may no longer sufficiently oppose their neighbor to properly grind and chew their food. Often the teeth wear unevenly and these uneven teeth predisposes a horse to periodontal disease, sharp molar hooks, and the accumulation of pockets of feed that creates infection around the tooth.

This series of events leads to a variety of problems including difficult or painful mastication, and “choke” (oesophageal obstruction) both of which may require veterinary attention. If your horse is a senior citizen it is advisable to have their teeth checked at least once a year or more frequently if there is a history of dental disease. Soaking pellets in a bucket of water to make a slurry will benefit a horse with more severely compromised dental function. If you notice weight loss, difficulty chewing or choke in your elderly horse, improper dental health should be your first concern.

Nutrition

If you notice weight loss and have ruled out dental disease, improper nutrition should be your second concern. Old horses have higher nutritional needs when compared to young horses, as they have more difficulty digesting and absorbing feed. The combination of poor dentition and decreased absorptive efficiency in the gut are largely responsible for the identified weight loss. Large particles that are incompletely ground are more difficult to digest in the failing intestines and largely passed through the intestine unaltered to the manure. Commercially available extruded feeds, processed feeds or pellets are already ground into smaller particles and are therefore easier to chew and digest AND often contain higher quality proteins.

A diet for an older horse should be:

  • Highly palatable and absorbable
  • Easy to chew and swallow
  • Dust free
  • Easy to digest
  • High quality energy, protein and fiber
  • Provide essential vitamins and minerals

A typical ration might consist of top quality hay (grass/alfalfa mix), highly digestible pellets in addition to free access to water and salt blocks.

Attention should also be given to the environment in whcih the elderly horse is fed. Ideally they should have minimal stress and competition from herdmates, suitable footing to minimize discomfort due to lameness, and adequate shelter from extreme weather elements.

Arthritis and Exercise

Arthritis (“arthro” = joint; “itis” = inflammation) is a combination of inflammation and degeneration of the tissues within a joint. As with human athletes, years of stress, injuries, and general wear and tear can result in painful and crippling arthritic changes in the joints of horses. The most susceptible joints include the knee (carpus) joint, fetlocks and coffin joints of the front legs, and the hocks and stifles of the hind legs. Weight management, optimal foot trimming and/or shoeing, low doses of anti-inflammatory medications such as phenylbutazone (Bute) or Equioxx® and joint supplements like glucosamine and chonroitin can greatly improve the quality of life for your arthritic horse. It is important to note that these drugs can negatively affect the stomach and kidney so these treatments should be used under the direction of your veterinarian.

Older horses will also benefit from consistent moderate exercise in the form of light riding with longer warm-up and cool down periods or pasture turn out. Regular exercise should help avoid stiffness and ensure greater mobility.

Colic

Colic simply refers to abdominal discomfort in the horse. While colic can affect horses of all ages there is a particular form associated with age. Older horses tend to develop benign fatty growths called lipomas in their abdomen. Lipomas grow on a stalk or pedicle that elongates, dropping a ball-shaped structure into the abdominal cavity. As the lipoma grows heavier, it causes the stalk or pedicle to lengthen. These masses with their elongated stalk become problematic when the pedicle wraps around a portion of the intestine and tightens. Known as a strangulating lipoma, it can be an extremely painful condition when it encircles the intestine and shuts off its blood supply. Surgical correction for this condition involves removal of the section of the intestines that is entrapped by the stalk of the lipoma and reconnecting the remaining unaffected ends of the intestines (known as a resection and anastomosis). Unfortunately, there is no way to detect these growths prior to episodes of colic.

Cushing’s Disease

Equine Cushing’s Disease, also known as Pituitary Pars Intermedia Dysfunction (PPID), typically affects horses greater than 16  years of age. PPID results from an overgrowth of part of the pituitary gland in the brain, producing an excess amount of the stress hormone cortisol in circulation.

Signs of PPID include:

  • lethargy and depression
  • pronounced localised fat pads on the shoulders, rump and above the eyes
  • growing a thick, coarse, curly coat which does not shed in the summer
  • excessive drinking, sweating, and urinating
  • laminitis

PPID should always be a consideration when an older horse develops laminitis or “founders” or suffers from persistent infections. Typical clinical signs include a curly, long hair coat and abnormal shedding patterns. However, not all horses show these classic outward signs. Horses with normal coats may be affected to some degree by PPID. While many body systems are affected by this disease, the most serious complication is laminitis. Once properly diagnosed, the quality of your horse’s life can be signifiantly improved with an appropriate treatment plan including daily medications such as Pergolide.

old horse
The typical curly, long-hair coat of a horse affected by Equine Cushing's Disease

As an aside, the American Association of Equine Pratitioners (aaep.org) is conducting a research project on pasture and PPID associated laminitis in horses. This project is supported by the AAEP Foundation and Prascend® (pergolide mesylate), a new drug that is manufactured by Boehringer Ingelheim Vetmedica, Inc. Because this drug has shown tremendous promise for the treatment of PPID, there is ongoing research to understand this disease more completely and interested individuas with horses that have been diagnosed with this condition are encouraged to contact our hospital.

Cancer

Like humans, horses are at risk for a variety of tumors, and this risk increases with increasing age. Sarcoids, melanomas and squamous cell carcinomas are the most common skin tumors of the horse. Sarcoids often grow rapidly, frequently becoming ulcerated and infected. They are commonly seen on the aged horse, and usually develop on sensitive areas of the body, such as the inner thigh, belly, eyelids, udder, sheath and dock. Sarcoids are notorious for recurring, and are locally aggressive but do not metastasize. Early diagnosis and treatment of sarcoids is essential. These tumors are more problematic and are not life threatening.

Most elderly grey horses have at least one melanoma. Melanomas (or meanocytosis as it is controvertial if this is a true tumor) may present as a slow growing grey mass that is generally less aggressive than sarcoids. They present as hard bumps and masses around the anus, tail, mouth and the back of the jaw. They are locally invasive and can create a problems due to their increasing size. An example of the problem that a melanoma can create is as a space occupying lesion is around the anus where it can grow large enough to impede the passage of feces. A single isolated lesion may not cause problems on its own initially, but should be surgically removed because it will likely grow larger. Early excision is recommended to prevent later ulceration and complications associated with larger size. In a very small percentage of horses, melanomas can become life threatening if they metastasize to the gastrointestinal tract or other organs. Older horses, especially grey horses, should be inspected regularly for signs of skin nodules or growths and their development monitored with your vet.

melanoma
Large locally invasive melanoma around the anus

Squamous cell carcinomas are usually found around the eyes, vulva or on the penis or sheath of older males and in areas of white skin. These tumors can be locally aggressive and ulcerative but typically do not metastasize. Surgical removal is often necessary before they affect the horse’s quality of life.

carcinoma
Squamous cell carcinoma on the penis

The chance of successful resolution of these tumors is greatly improved by early diagnosis and treatment. If you notice a small lump under the skin, ocular discharge, a foul odor coming from the penis, bleeding from the penis, difficulty urinating or defecating, or any change in your horse's normal behavior, have your veterinarian examine your horse

Cataracts

A cataract is a cloudy opacity which forms in the lens of the horses eye. It is generally a progressive lesion that can lead to sight loss in the affected eye. The partially sighted horse requires careful management, and should always be made aware of your apporach through audible cues. In severe cases these cataracts can be surgically removed by a veterinary ophthamologist.

EYES

Liver and Kidneys

Signs that a horse may be suffering from liver and kidney problems are poor body and coat condition, loss of appetite, and weight loss. Prolonged use of certain drugs to manage other health problems may have a lasting adverse affect on a horse’s liver and kidney function.

Your veterinarian can can run blood tests to assess liver and kidney function. Liver or kidney issues can often be improved with medication or dietary changes.

Vaccination and Deworming

As elderly horses often have a less effective immune system it is essential to continue vaccination and parasite control. A quick response to ailments, injuries or a decline in fitness can keep your older horse from having a serious setback. That means less worry for you and a better quality of life for your companion.

Damian McEntee, MVB

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