The Experimental Infection of Ponies with Contagious Equine Metritis

Abstract

SUMMARY Four pony mares were readily infected with the organism of contagious equine metritis by intracervical inoculation and one by coitus with an infected stallion. Infected mares developed an acute endometritis with local destruction of the endometrial epithelium. In 2 experimentally infected mares, infection appeared to have been spontaneously eliminated from the genital tract within 3 to 4 weeks. A third mare however remained persistently infected in the clitoral fossa over a long period and was a symptomless carrier. Four pony stallions were readily infected in the urethral fossa and the organism survived for varying periods without giving rise to any signs of infection. From 2 of these animals it appeared eventually to have been eliminated spontaneously. An experimentally infected stallion transmitted infection to a healthy mare by coitus. Bacteriological examination of infected pony stallions may occasionally give false negative results and fail to reveal the organism in the external genitalia. Repeated bacteriological examinations need to be undertaken before it can be concluded that a stallion is free of infection. RÉSUMÉ Cinq poneys femelles ont été infectées avec l'agent de la métrite contagieuse équine 1977, par inoculation cervicielle. Les juments infectées ont montré une endométrite aigue avec destruction locale de l'épithélium utérin. Deux des juments infectées furent spontanément guéries en trois ou quatre semaines. Une troisième jument demeura infectée durant une longue période au niveau de la fosse clitoridienne et se révéla être un porteur asymptomatique. Quatre poneys mâles furent infectés au niveau de la fosse urétrale et l'organisme pathogène y survécu durant des périodes variables sans provoquer aucun signe d'infection clinique. II semble que deux de ces étalons aient éliminé spontanément l'agent pathogène. L'un des étalons infecté expérimentalement transmit la maladie à une jument saine, lors d'un coit. Le controle bactériologique des étalons infectés donna parfois des résultats négatifs, ne permettant point de constater la présence de la bactérie au niveau du tractus génital externe. Des examens bactériologiques répétés sont nécessaires avant de conclure à la non contamination d'un étalon. ZUSAMMENFASSUNG Fünf Ponystuten konnten leicht mit dem Erreger der CEM durch intracervicale Inokulation infiziert werden. Infizierte Stuten entwickelten eine akute Endometritis mit lokaler Zerstörung des Epithels. Zwei infizierte Stuten schienen die Infektion innert 3–4 Wochen spontan überwunden zu haben. Eine dritte Stute dagegen blieb während langer Zeit infiziert (Klitorisgrube) und wurde zum symptomfreien Träger. Vier Ponyhengste konnten in der Fossa urethralis ohne Schwierigkeiten infiziert werden; der Keim überlebte während unterschiedlicher Zeit, ohne zu klinischen Anzeichen einer Infektion Anlass zu geben. Zwei der Hengste schienen die Infektion spontan eliminiert zu haben. Ein experimentell infizierter Hengst übertrug die Infektion durch den Koitus auf eine gesunde Stute. Die bakteriologische...

Lesions of Contagious Equine Metritis in Mares

“…When two pony mares were killed and necropsied four and seven days after inoculation [6], widespread acute endometritis was reported, but in addition lesions were described that we did not observe. These were destruction and apparent pseudostratification of surface epithelium of the uterus and regenerative activity in the uterine glands.…”

“…This could explain some of the loss of surface epithelium. We consider pseudostratification [6] and luminal epithelial proliferation [9] to be tangential sections and epithelial pleomorphism with migratory inflammatory cells as well as karyorrhectic debris therefrom.…”

“…Microscopic lesions in two pony mares killed four and seven days after experimental infection were mild acute inflammation of fimbriae of the fallopian tubes, widespread acute erosive endometritis and subacute vaginitis [6]. Lesions have been described [9] in uterine biopsy specimens taken from ten naturally infected thoroughbreds two to 205 days after service and one experimentally infected pony sampled at intervals over 37 days.…”

“…In the acute phase of the disease, gross lesions have been described as endometrial congestion with clear mucoid material in the lumen [6], pyomucometra [lo], complete sloughing of the endometrium [2], edema and hyperemia of the cervix [4]. Microscopic lesions in two pony mares killed four and seven days after experimental infection were mild acute inflammation of fimbriae of the fallopian tubes, widespread acute erosive endometritis and subacute vaginitis [6].…”

Characterization of the major antigens of Haemophilus equigenitalis (contagious equine metritis organism)

“…The morphological, cultural, general bacteriological and pathogenic properties of this organism have been closely studied, particularly in relation to the development of procedures for its identification and for determining its taxonomic position (Platt, Atherton & Simpson, 1978;Rommel et al 1978;Shreeve, 1978;Timoney & Ward, 1978;Swaney & Breese, 1980).…”