Abstract:
Introduction:
Equine encephalosis is a systemic disease of horses caused by equine encephalosis virus. This virus is
an Orbivirus that is transmitted by biting midges (Culicoides species). Equine encephalosis is often
reported as a subclinical infection with a relatively limited number of clinical cases showing
predominantly fever, with minimal morbidity and mortality. Rare instances of neurological disease
have also been associated with the virus.
Clinical relevance:
Information regarding the clinical presentation of equine encephalosis is underrepresented in
current scientific literature. This study aims to contribute to a more detailed conceptualization of the
significance of the disease and its clinical impact.
Method:
A retrospective, descriptive, observational study was performed on data obtained from the
University of Pretoria’s clinical database for cases identified with equine encephalosis over the
period 2013-2023. Data from the history, clinical signs and clinicopathological findings were
analysed. The clinical presentation and clinicopathological findings are reported.
Results:
A total of 28 horses conformed to the study parameters as having clinical infection with equine
encephalosis virus. Pyrexia was apparent in 89.2% of these cases. Other clinical findings included
tachycardia (64.3%), tachypnoea (46.4%), colic (39.3%), neurological signs (21.4%), peripheral
oedema (14.3%), and icterus (10.7%). Evaluation of the clinicopathological findings identified
lymphopenia (86.7%), thrombocytopenia (76.0%), leukopenia (48.0%), immature neutrophilia
(31.8%), and mature neutropenia (27.3%).
Conclusion:
Equine encephalosis can result in a wide variety of clinical signs in horses and is associated with
changes in haematology variables. These haematological changes suggest a systemic response to
the viral infection. Further research into the pathophysiology of equine encephalosis is required to
better understand the disease and its clinical relevance.
