52
46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
semen for AI in transmission was highlighted. The majority of identified carrier mares
were infected via this route, despite inclusion of antimicrobial- containing extenders
to contaminated semen. A notable epidemiologic feature was the non-venereal,
horizontal transfer, presumably via fomites between stallions (including non-breeding
animals), predisposing environmental factors consequent to management practices in
certain breeds or centralised artificial breeding facilities.
Extensive testing of horses within a relatively short interval and encompassing a wide
variety of breeds was successfully achieved via a unique web-based platform. This
was despite a reliance on genital swabbing from multiple locations on multiple
occasions and assay via a combination of both bacteriology and PCR to enhance
sensitivity. The practicalities, throughputs and costs associated with future similar
surveillance exercises would be greatly enhanced by a standardised sampling
protocol in combination with a validated, robust PCR assay. The sex-biased
association with positively detected carriers justified prioritising the targeting of
stallions in surveillance exercises.
Application of in-treatment monitoring via PCR assay was a useful innovation in
detecting the variable response and duration of treatment in individual carrier
stallions. This may potentially benefit the management and duration of animals
undergoing treatment under quarantine conditions.
Future areas that warrant investigation include defining any direct effects of CEM on
reproductive performance and the economics of artificial breeding as an essential
step in creating an awareness of any potential significance to artificial breeding
populations. Although recent reports reflect a greater understanding of the roles of
unapparent carriers and chilled semen, the transmission risks in association with
cryopreserved semen and embryos are still undefined and this route remains as a
potential Trojan horse. Research supporting the validation and acceptance of a
robust PCR assay has significant benefits for future disease surveillance, diagnostics
and international trade and movement of horses and their products.
References
1.
2.
3.
May, C.E., Schulman, M.L., Gerstenberg, C., Grobler, A., Mphele, A., and Guthrie, A.J. (2012).
Confirmation of the first outbreak of contagious equine metritis in South Africa. In: Squires,
E.L., Orsini, J.A., Evans, J. (Eds.) 9th International Conference on Equine Infectious Diseases,
Equine Veterinary Science 32:77
May, C.E., Schulman, M.L. Keys, B. and Guthrie, A.J. (2013). The distribution of carrier status
of T. equigenitalis in stallions and exposed mares in South Africa. Clinical Theriogenology, 5(3):
398
Schulman, M.L., May, C.E., Keys, B. and Guthrie, A.J. (2013). Contagious Equine Metritis:
Artificial reproduction changes the epidemiologic paradigm. Veterinary Microbiology, 167:2-8
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