Vet360 Vol 4 Issue 3 June 2017 Vet360 - Page 8

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