Contagious equine metritis—epidemiology and control

Abstract

Summary Since 1977, when contagious equine metritis (CEM) was first described and etiologically defined as a previously unrecognized venereal disease of the horse, the disease has been reported from countries in Europe, Asia, Australia, North and South America. The potential for spread of CEM through the international movement of horses was realized early, with the introduction of the disease into some countries following the importation of a carrier animal. The carrier state has been confirmed in both the mare and the stallion, with such animals providing a focus for initiating fresh outbreaks of the disease by dissemination of the causal organism primarily by the venereal route. Successful control of CEM within an equine population requires the identification and treatment of culture-positive mares and stallions. Although such a control program is based primarily on the bacteriologic screening of both stallion and mare populations to detect clinical and carrier animals, it also necessitates the prompt diagnosis of CEM and implementation of the requisite standards of stud management hygiene if spread of the disease is to be prevented. Removal of the clitoral sinuses and topical antimicrobial treatment of the clitoral area have been additional control measures required of certain mares imported into the United States from countries in which CEM has been reported. The number of outbreaks of the disease has been greatly reduced if not eliminated in those countries in which a code of practice for the control of CEM has been in force for several years.