Prevalence of Disease with Inference of Equine Coronavirus Infection Among Horses Stabled in a Draft-Horse Racecourse

Abstract

An outbreak of equine disease with pyrexia and anorexia occurred from December 2004 to March 2005, affecting 191 heavy horses (about 30 percent of stabled horses) at the drafthhorse racecourse in Obihiro City, Hokkaido, Japan. Neutralization antibody titers to bovine coronavirus rose significantly in 14 paired sera out of 21 diseased horses. A highly homologous gene to that of equine coronavirus (NC99) was detected in fecal samples from the diseased horses. However, known pathogens and genes excluding the coronavirus were not detected from any pituita or fecal samples from the diseased horses. In addition, the antibody titers did not rise significantly in the serological tests of 21 diseased horses for equine herpes virus type 1, equine influenza virus, getah virus, equine rotavirus, equine rhinitis A virus, equine adenovirus, equine arteritis virus, strangles, and equine paratyphoid. From these facts, it was inferable that the outbreak of the disease was caused by infection with equine coronavirus.