Clinical signs and clinical pathology findings in horses with equine encephalosis at the Onderstepoort Veterinary Academic Hospital, South Africa

Dissertation (MMedVet (Equine Medicine))--University of Pretoria, 2024.

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.

Companion Animal Clinical Studies

MMedVet (Equine Medicine)

Unrestricted

Faculty of Veterinary Science