Equine Proliferative Enteropathy: A Growing Concern

As weaning time approaches, your foal looks healthy as can be. But not long after, he's lost weight, looks smaller, and seems depressed. What happened to the thriving colt you weaned? According to veterinarians, equine proliferative enteropathy (EPE), a gastrointestinal disease of foals and weanlings that's increasing in prevalence across the country, could be a diagnostic possibility.

EPE Before

An EPE-affected foal (above), and the same foal after recovery (below).


"Equine proliferative enteropathy caused by (the bacterium) Lawsonia intracellularis is an emerging disease that is associated with significant financial losses," said Nicola Pusterla, DVM, PhD, Dipl. ACVIM, an associate professor in the Department of Medicine and Epidemiology at the University of California, Davis.

Equine proliferative enteropathy causes the mucosal lining in a weanling's small and large intestine to thicken, resulting in reduced absorption of nutrients and a loss of protein from the body. The disease generally isn't fatal; however, it can result in financial loss if it affects, for example, Thoroughbred foals scheduled to be sold at auction, as smaller foals might bring lower prices.

Infected horses can be classified as classic (showing clinical signs; more on this in a moment) or subclinical cases (not showing signs of infection other than transient lower daily weight gain. Healthy horses are infected with L. intracellularis via the fecal-oral route. These subclinical cases might also shed this bacterial organism, making them another source of environmental contamination. Pusterla and colleagues revealed in recent research that as many as 65% of apparently healthy foals and horses (residing on farms where clinical cases of EPE were diagnosed) have been exposed to the bacterium.

Foals that have recently undergone dietary changes, been weaned or transported, or are experiencing concurrent disease are more susceptible to developing EPE after L. intracellularis exposure.

Clinical signs of the disease in infected youngsters include:

  • Slow growth or failure to thrive;
  • Weight loss;
  • Fever;
  • Depression;
  • Poor appetite;
  • Edema (fluid swelling) of the ventral region (belly), throat latch, sheath, and limbs; and/or
  • Occasional diarrhea and colic.

Pusterla explained that veterinarians diagnose EPE through a combination of clinical signs, low blood protein levels, the detection of L. intracellularis antigen in feces through polymerase chain reaction testing, and/or L. intracellularis antibodies in blood serum. Providing supportive care and administering antimicrobial medications will lead to complete recovery in most foals.

According to Pusterla, he and other internal medicine specialists have been diagnosing EPE more frequently over the past few years: "Cases of EPE have been increasingly reported, and the disease has almost reached a worldwide distribution since it was first described in the 1980s."

In recent years the United States, Canada, Europe, South Africa, South America, Japan, and Australia have all reported growing numbers of EPE cases.

Researchers are still working to fully understand the disease and bacterium that causes it, along with examining the reason for the apparent increase in cases.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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