If someone had said "equine proliferative enteropathy" 10 years ago, chances are most horse breeders would have shrugged their shoulders and paid little mind. Today, however, many breeders are mindful of this still-emerging young horse disease caused by the Lawsonia intracellularis bacteria. Researchers have made great strides in comprehending many facets of the disease. Recently, a team from the University of Kentucky, using a newly developed assay, took several steps forward in understanding L. intracellularis' environmental prevalence on certain horse farms compared to its seroprevalence (presence of positive serum antibodies) in horses residing on those farms. Allen Page, DVM, a PhD candidate at the University of Kentucky’s Gluck Equine Research Center, presented the findings during a presentation at the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas.

Equine proliferative enteropathy (EPE) has been reported worldwide and is gaining prevalence in the United States. L. intracellularis invades intestinal crypt cells, primarily in the small intestine, and causes thickening of the intestinal lining. This thickening leads to clinical signs such as anorexia, weight loss, reduced daily weight gain, fever, lethargy, depression, peripheral/ventral edema (fluid swelling), and sometimes colic and diarrhea. Reduced daily weight gain and weight loss can be a costly problem for many Thoroughbred breeders, as smaller foals tend to bring lower prices at auction. The current lack of definitive diagnostic tests is another frustration for breeders and veterinarians alike.

Recently, Page and a team of researchers developed a modified enzyme-linked immunosorbent assay (ELISA) test that detects antibodies to L. intracellularis—the first serologic assay able to detect the antibodies and, thus, L. intracellularis exposure. Using this test, the team evaluated the seroprevalence of L. intracellularis among 337 Thoroughbred foals and weanlings residing on 25 Central Kentucky farms.

"Case information from the three years preceding the study was used to classify farms as having no prior recent history of EPE, a suspected history of EPE, or a confirmed history of EPE," he explained. Then, from August 2010 to January or February 2011 (the study officially ended in January, but some farms opted to have foals tested in February as well), the research team collected monthly serum samples from the aforementioned foals, testing them for L. intracellularis-specific antibodies