Infection with Lawsonia intracellularis (most often seen in weanlings) can cause edema (fluid swelling) beneath the abdomen and in the lower limbs, lethargy, anorexia, diarrhea, fever, colic, and weight loss. It is a "true emerging disease with more cases every year," according to Nicola Pusterla, DVM, Dipl. ACVIM, associate professor of veterinary medicine and epidemiology at the University of California, Davis.

At the 2008 American Association of Equine Practitioners convention, held Dec. 6-10 in San Diego, Calif., Pusterla discussed the effectiveness of three vaccination strategies against L. intracellularis, which causes proliferative enteropathy (a spreading intestinal disease). "Although the clinical entity (L. intracellularis infection), diagnostic evaluation, and treatment of affected foals have been well-established and described, preventive measures have remained largely unaddressed," he noted.

Pusterla et al. investigated the immune response and fecal shedding of L. intracellularis following two doses of a modified-live vaccine (Enterisol Ileitis from Boehringer Ingelheim Vetmedica) given orally or intrarectally three weeks apart. Fifteen healthy, L. intracellularis-negative foals were divided into three groups of five, with one foal in each group remaining unvaccinated as a sentinel