UKVDL Seeing Increased Lawsonia Submissions

According to a March University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) bulletin, the lab is seeing a statistically significant increase in positive Lawsonia intracellularis test results as compared to recent years.

Equine proliferative enteropathy (EPE) is an emerging disease of horses that has been reported worldwide. EPE is caused by L. intracellularis, a gram-negative bacterium that invades intestinal crypt cells, primarily in the small intestine, and causes thickening of the intestinal lining. This thickening leads to the clinical signs associated with EPE, including anorexia, weight loss, fever, lethargy, depression, and peripheral/ventral edema (fluid swelling), with colic and diarrhea seen occasionally. A thickened small intestinal wall observed by a veterinarian via abdominal ultrasound, although not reliably observed, is highly suggestive of EPE. Clinical EPE is typically found in weanlings and young yearlings, with only a few reports of older horses being affected.

Lawsonia intracellularis infections have been reported in a number of species, including pigs and laboratory animals, but not humans. EPE is significant not just because of the clinical aspects of the disease, but also because of its economic importance.

Veterinarians can confirm a diagnosis using PCR (polymerase chain reaction, a biochemical technology in molecular biology) on feces. Because the disease's epidemiology is not well-understood, practitioners have not yet determined effective prevention methods. The University of California, Davis, is testing a swine vaccine for safety and efficacy.

The UKVDL can assist in diagnosing an L. intracellularis infection by performing a PCR test, which are run daily, with a one- to two-day turnaround. Samples sent to the laboratory should be 5 grams intestinal scraping; fecal specimen; fecal swab; and/or scraping of mucosa of harvested tissue. Specimens should be submitted in screw-cap tubes. The cost is $35 in-state and $52 out-of-state, plus a $10 accession fee.

For more information, contact the UKVDL at 859/257-8283 or visit

Information provided by UKVDL’s Jacqueline Smith, PhD, Epidemiology Section Chief; Erdal Erol, DVM, PhD, Diagnostic Microbiology Head; and Craig Carter, DVM, PhD, Dipl. ACVPM, Director of the UKVDL and Professor of Epidemiology

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