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Clinical presentation, progression and management of 5 cases of Ross River virus infection in performance horses located in southeast Queensland: A longitudinal case series


Publication date: Available online 6 January 2017 Source:Journal of Equine Veterinary Science Author(s): A.J. Barton, H. Bielefeldt-Ohmann

Background Ross River virus (RRV), a mosquito-transmitted alphavirus prevalent in Australia, is believed to cause poor performance, lethargy and muscle stiffness in Australian horses. However, disease progression and management is poorly documented. A better understanding of disease presentation, acute therapy and long-term management is required. Objectives To describe clinical presentation, diagnosis, acute treatment and long term management of RRV-infection in horses Study design Retrospective case series Methods Clinical and diagnostic data were obtained from both veterinary records and owner interviews for 5 performance horses that presented with acute poor performance coupled with serological evidence of RRV exposure. Clinical and owner reports were evaluated from the time of presentation until the horses appeared asymptomatic and had returned to normal performance. Results RRV was suspected to be the cause of generalized muscle stiffness and poor performance in 5 performance horses located in southeast Queensland between 2011 and 2015. Clinical symptoms included pyrexia, tachypnoea, exercise intolerance, generalized muscle stiffness, synovial effusion, and oedema of the lower limbs. Serological investigations (ELISA and/or virus neutralization assay) detected antibody responses to RRV. Horses were treated with non-steroidal anti-inflammatory drugs (n=5) and disease-modifying osteoarthritis drugs (n=2). Most horses returned to previous athletic capabilities between 7 and 12 months after onset of symptoms. Main limitations Not all horses in the study had pre-clinical serology or submitted paired blood samples for serology, meaning assumption of acute infection in those horses was made based on clinical signs coupled with positive serology Conclusion RRV is a significant but poorly understood cause of poor performance in Australian horses. This report is the only one to document longitudinal management of performance horses affected by RRV infection. Much more research is needed to gain a better understanding of this infection in horses.