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)