Lesions of contagious equine metritis in mares

Reproductive Disorders in Horses

Reproductive disease is relatively common in the horse, resulting in a variable, yet significant, economic impact on individual horsemen as well as the entire industry. Diverse expertise from the veterinary community ensures and improves individual and population health of the horse. From a pathology and diagnostics perspective, this review provides a comprehensive overview of pathology of the male and female equine reproductive tract. Recognition by clinical and gross features is emphasized, although some essential histologic parameters are included, as appropriate. Where relevant, discussion of ancillary diagnostic tests and approaches are included for some diseases and lesions.

Venereal disease

Equine venereal infections of concern in the United States include EHV-3, T. equigenitalis, P. aeruginosa, and K. pneumoniae. Stallions may also harbor EAV in the genital tract and transmit the virus to mares during coitus. With the exception of EHV-3, the stallion generally remains asymptomatic while transmitting infections to mares during breeding. Methods for diagnosis, treatment, and control of these infections are discussed.

Transmissibility of the contagious equine metritis organism for the cat

A group of SPF cats were moderately susceptible to the causal organism of contagious equine metritis (CEM) following intra-uterine or intrapreputial challenge with an Irish streptomycin resistant strain isolated from a clinically infected mare. Subclinical infections were established in only 50% of the cats, none of which became long-term carriers of the organism. Cytological examination of vaginal smears was of no diagnostic value in confirming infection in inapparently infected cats. Bacteriological responses after primary or secondary challenge with the CEM organism were essentially similar, with one exception, a female cat in which there was possible evidence of local immunity persisting after the primary infection. Efforts to reactivate shedding subsequent to the immediate post-challenge period were unsuccessful. Throughout the experimental period, the cats remained sero-negative to the complement-fixation test, and they failed to develop any significant increase in the levels of antibody activity as measured by the kinetics-based ELISA or KELA system. On day 89 after primary challenge, the cats were euthanized and various sites in the genitourinary tract and the internal iliac lymphatic glands subjected to bacteriological and pathological examination for evidence of CEM infection with negative results.

The findings of this study, although establishing the transmissibility of the CEM organism for the cat, demonstrate the limited value of this species as an experimental model system for the disease in the horse.