Clinical, bacteriologic, serologic, and pathologic features of infections with atypical Taylorella equigenitalis in mares

Jonathan B. KatzNational Veterinary Services Laboratories, USDA, Animal and Plant Health Inspection Service, Ames, IA 50010.

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Lawrence E. EvansDepartment of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011.

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David L. HuttoNational Veterinary Services Laboratories, USDA, Animal and Plant Health Inspection Service, Ames, IA 50010.

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Linda C. Schroeder-TuckerNational Veterinary Services Laboratories, USDA, Animal and Plant Health Inspection Service, Ames, IA 50010.

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Ann M. CarewNational Veterinary Services Laboratories, USDA, Animal and Plant Health Inspection Service, Ames, IA 50010.

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J. Michael DonahueLivestock Disease Diagnostic Center, University of Kentucky, Lexington, KY 40546.

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Dwight C. HirshDepartment of Veterinary Pathology, Microbiology, & Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616.

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Abstract

Objective—To characterize clinical, serologic, bacteriologic, cytologic, and pathologic endometrial responses of mares to 2 donkey-origin atypical bacterial isolates resembling Taylorella equigenitalis.

Design—Prospective in vivo study.

Animals—10 healthy mares.

Procedure—Mares in estrus (2/group) were inoculated by intrauterine infusion with 2 isolates of classic T equigenitalis or 2 isolates of atypical Taylorella sp or were sham-inoculated. Bacteriologic, serologic, clinical, uterine, cytologic, and pathologic endometrial responses were assessed 4, 11, 21, 35, and 63 days after inoculation and on day 111 in mares with positive culture results on day 63.

Results—One atypical isolate failed to cause infection. The second atypical isolate and both classic T equigenitalis isolates induced similar transient metritis and cervicitis. Both classic isolates and 1 atypical isolate induced anti-T equigenitalis complement-fixing antibodies detectable at day 11. Classic isolates and an atypical isolate provoked intense neutrophilic endometritis followed by a resolving, subacute, neutrophilic-mononuclear endometrial response. The atypical isolate and classic isolates were recovered from the uterus, clitoral fossa, or clitoral sinus of one or both exposed mares for as long as 111 days.

Conclusions and Clinical Relevance—Atypical Taylorella sp infections should be considered as a differential diagnosis of equine infertility in US-origin mares, even those not exposed to stallions from countries where contagious equine metritis occurs. The origins and prevalence of atypical Taylorella sp infection in US horses and donkeys are undetermined. (J Am Vet Med Assoc 2000;216:1945–1948)

Abstract

Objective—To characterize clinical, serologic, bacteriologic, cytologic, and pathologic endometrial responses of mares to 2 donkey-origin atypical bacterial isolates resembling Taylorella equigenitalis.

Design—Prospective in vivo study.

Animals—10 healthy mares.

Procedure—Mares in estrus (2/group) were inoculated by intrauterine infusion with 2 isolates of classic T equigenitalis or 2 isolates of atypical Taylorella sp or were sham-inoculated. Bacteriologic, serologic, clinical, uterine, cytologic, and pathologic endometrial responses were assessed 4, 11, 21, 35, and 63 days after inoculation and on day 111 in mares with positive culture results on day 63.

Results—One atypical isolate failed to cause infection. The second atypical isolate and both classic T equigenitalis isolates induced similar transient metritis and cervicitis. Both classic isolates and 1 atypical isolate induced anti-T equigenitalis complement-fixing antibodies detectable at day 11. Classic isolates and an atypical isolate provoked intense neutrophilic endometritis followed by a resolving, subacute, neutrophilic-mononuclear endometrial response. The atypical isolate and classic isolates were recovered from the uterus, clitoral fossa, or clitoral sinus of one or both exposed mares for as long as 111 days.

Conclusions and Clinical Relevance—Atypical Taylorella sp infections should be considered as a differential diagnosis of equine infertility in US-origin mares, even those not exposed to stallions from countries where contagious equine metritis occurs. The origins and prevalence of atypical Taylorella sp infection in US horses and donkeys are undetermined. (J Am Vet Med Assoc 2000;216:1945–1948)

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