Disease Conditions in Geriatric Horses

This report discusses diseases diagnosed in horses 15 years of age and older presented to the University of Kentucky Livestock Disease Diagnostic Center for necropsy examination. A total of 817 horses 15 years of age or older were necropsied between January 1994 and July 1999. Fifty-four percent were 15-19 years of age, 33% were 20-24 years, 9% were 25-29, and 4% were 30 years and older. The oldest equine was a 45-year-old pony and the oldest horse was a 42-year-old mixed breed. In the 30 years and older group, one-third (nine of 27) were ponies, while in the 15-19 year age group, only 3% were ponies, suggesting greater longevity for pony breeds.

Many different conditions were diagnosed; however, the majority of diagnoses pertained to the gastrointestinal, musculoskeletal, and reproductive systems, as well as various types of neoplasia. Other, less common diagnoses included diseases affecting the nervous system, liver, heart, and lungs—each group represented approximately 3%-8% of the cases.

Conditions involving the gastrointestinal tract were mainly displacements or twists with strangulation of some portion of the tract, including many cases of rupture of the stomach or bowel. With the common occurrence in older horses of abdominal lipomas (fat tumors) with cord-like stalks, a number of the cases of strangulation were the result of lipomas wrapping around the intestine.

The overwhelming majority of conditions involving the reproductive system were cases of rupture of the uterine artery and fatal hemorrhage, with a few cases of uterine perforation or

laceration also diagnosed. Uterine artery rupture occurs most commonly in older mares around the time of parturition. It was most common in the first two age groups, which were still reproductively active, becoming less common in the two older groups, which were beyond the normal reproductive limits of the mare.

Diagnoses involving the musculoskeletal system represented a variety of conditions, with fractures, laminitis, arthritis, and other trauma (in that order) making up the majority of the cases. The percentage of disorders affecting the musculoskeletal system was fairly constant in each of the age groups.

An increased incidence of neoplasia is associated with advanced age in animals, and neoplasia commonly was diagnosed in older horses. In the two oldest groups, neoplasia was the most common individual diagnosis. Common types of neoplasia in decreasing order included pituitary adenoma, melanoma, squamous cell carcinoma, and lymphoma.

In general, infectious diseases are an important cause of morbidity and mortality in horses. However, infectious diseases were a much less-common cause of illness in geriatric horses compared to conditions that were anatomical, traumatic, or neoplastic in nature. Only approximately 10%-15% of all diagnoses had an infectious etiology. These were most commonly pneumonia and enteritis cases.

Based on the findings of this report, some basic recommendations can be made to owners of geriatric horses. With the large number of gastrointestinal disorders, it is recommended that horses be fed diets with ample high-quality roughage, and that abundant water and appropriate exercise are provided.

Regular deworming and dental care are also essential in older horses to ensure optimal gastrointestinal function. The environment should be policed for hazardous areas, and stocking rates should be appropriate for the pasture.

Older foaling mares, especially following difficult deliveries, should be closely monitored and veterinary assistance sought immediately if undue pain or signs of shock are observed.

—From Equine Disease Quarterly, Funded by Underwriters at Lloyd’s of London, Brokers, and their Kentucky agents

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