INFECTIOUS DISEASES
African Horse Sickness
in Dogs
A Clinical and Diagnostic Update
Nicolize O’Dell, BVSc
Section of Pathology, Department of Paraclinical Sciences, Faculty of Veterinary Science,
University of Pretoria.
Reviewed and edited by Johan Steyl, BVSc, MSc (Path)
African horse sickness (AHS) is a non-contagious,
arthropod borne viral disease affecting horses char-
acterised by failure of the circulatory and respiratory
systems. (2) Historically it was shown that AHS could
be transmitted to dogs through the consumption
of infected horse meat (3-6) and that the likelihood of
dogs contracting this disease naturally was extremely
low, as the vector Cullicoides imicolai do not prefer
to feed on dogs (1) . More research is needed to deter-
mine the complete epidemiology of canine AHS as it
would appear that alternative modes of transmission
may exist in canines such as ticks and midges.
The first case of cAHS that was not associated with
infected meat consumption was confirmed in 2006
at the Section of Pathology, Faculty of Veterinary Sci-
ence, University of Pretoria. Since then, at least an-
other 33 dogs have beeb diagnosed with cAHS at this
laboratory alone. In 2008 six cases were confirmed, in
2009 four, 2010 one, 2011 one, 2013 one, 2014 four,
2016 four and interestingly this year (2017) already
more than twelve. The apparent sharp increase in
cAHS incidence in 2017 is probably a combination of
high rainfall period following a long drought increas-
vet360
Issue 03 | JUNE 2017 | 8
ing the naïve dog population, as well as increased
awareness among local veterinarians about cAHS.
This condition seems to mostly occur in semi-urban
areas close to small-holdings where horses are pres-
ent, as in the case of the areas surrounding Onderste-
poort and Roodeplaat dam. The signalment of many
of the affected dogs included mostly large breed dogs
that are typically kept outside as guard dogs. This fea-
ture supports the “vector theory” in cAHS as these ani-
mals run a higher risk of threshol