Emerging Disease in Foals

A bacteria that causes weight loss, colic, diarrhea, and hypoproteinemia (abnormally low protein in the blood) in foals is being seen more often in North America and Europe. The affected foals are usually four to eight months old, but can be older. While the causative bacteria Lawsonia intracellularis can cause severe disease, it is very treatable if caught early.

Lawsonia intracellularis causes an equine proliferative enteropathy, which means a spreading disease involving the intestines--in this case, protein loss from the gastrointestinal tract. The disease is characterized by anasarca, or generalized swelling, internally and externally (including the head). According to Doug Byars, DVM, Dipl. ACVIM, Dipl. ACVECC, head of the internal medicine unit at the Hagyard-Davidson-McGee veterinary firm in Lexington, Ky., this disease has been recognized in Kentucky over the past three or four years. It has been diagnosed again in 2003.

Foals usually ingest the bacteria; while it rarely affects all the foals on a single farm, there can be multiple affected foals on a single premise. Outbreaks have been noted (especially in Canada). England and Ireland also have cases reported in veterinary literature. Symptoms include depression, rapid weight loss, diarrhea, colic, and edema. One scientific report noted that a rough haircoat and a potbellied appearance were common findings. Diagnosis is through these symptoms, by finding the bacteria in fecal samples using a PCR (polymerase chain reaction) test, or by detecting antibodies to L. intracellularis in blood serum (which detects exposure) at a specialized laboratory (the Kentucky Livestock Disease Diagnostic Center has this capability, noted Neil Williams, DVM, PhD, a pathologist at the Center). Horses which die can be diagnosed through pathology.

Most of what is known about this disease in animals is through a similar disease in pigs. The bacteria can affect many animals, including hamsters, dogs, ferrets, rabbits, deer, and sheep. No one knows the prevalence of this bacteria in normal horse populations. The good news, according to Nathan Slovis, DVM, Dipl. ACVIM, of Hagyard-Davidson-McGee, is that this disease is easily treated if detected quickly. "We have 100% success with treatment if they are caught early," he said. Treatment consists of antibiotics, plasma, and supportive care, usually in a hospital setting, for three to five days.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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