Equine proliferative enteropathy (EPE) is an important intestinal disease of young foals, caused by a bacteria called Lawsonia intracellularis. The disease was first reported in horses in 1982. EPE is found worldwide, with cases reported in North and South America, Africa, Australia, and Europe. Foals with EPE will most often develop noticeable swelling (edema) under the skin, particularly in between the front legs, scrotal area in colts, at the throatlatch, and occasionally in the lower portions of the legs. Other clinical signs that are similar to several other gastrointestinal diseases of foals include fever (101.3°F (38.5°C)), loss of appetite, rough hair coat, diarrhea, colic, and weight loss. Foals with EPE may also have concurrent disorders such as gastric ulcers, intestinal parasites, and respiratory tract infection.
L. intracellularis is thought to be transmitted by fecal-oral route, from infected animals that shed the organism within their feces. Several domestic and wild animals are known to be carriers of the organism, which act as reservoirs, the most important being rabbits, dogs, cats, mice and rats. Exposure to pig feces is another potential source of infection for horses. L. intracellularis can survive for 1 to 2 weeks in the environment during the winter season.