Equine Disease Quarterly | EQUINE
to have a higher incidence of nocardioform placentitis.
Although there does seem to be an association between
a hot and dry August and September preceding an
increase in nocardioform cases, the causal relationship
is less clear. Other members of the actinomycetes, such
as Rhodococcus equi, are soil-dwelling pathogens that
are associated with hot, dry, dusty environments. It is
worth considering that the actinomycetes responsible
for nocardioform placentitis may also originate as soilborne
organisms, despite the failure thus far to isolate
these pathogens from environmental sources. Related
members of Amycolatopsis and Streptomyces are well
characterized as soil-associated microorganisms, and a
likely environmental association (hot, dry periods in late
summer) may be associated with the disease.
It appears likely that the pathogenesis of
nocardioform placentitis is multifactorial and may
involve environmental conditions (hot, dry periods
in late summer) and possibly effects related to host
susceptibility. Pregnancy in many species, including the
mare, involves some degree of immunosuppression,
and many actinomycetes are more pathogenic in
immunocompromised hosts. More research is needed
to better unravel this complex disease process in the
mare.
CONTACT:
Barry A. Ball, DVM, PhD, DACT, [email protected], (859) 218-
1141, Maxwell H. Gluck Equine Research Center, University of
Kentucky, Lexington, Kentucky
• Volume 22 Issue 02 | June 2020 •
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