Can West Nile virus cause disease in horses?
In 1999, 25 New York horses with neurological signs were identified as cases of WNV infection. These horses presented with signs of ataxia, difficulty walking, knuckling over, head tilt, muscle tremors, and the inability to rise. Of these 25 horses, nine (36%) died or were euthanised. WNV was identified in the tissue samples and specific WNV antibody was found. The 16 surviving horses all recovered and also developed WNV antibody titers. In 2000, the National Veterinary Services Laboratories confirmed 60 horses with WNV infection from the states of Connecticut (7), Delaware (4), Massachusetts (1), New Jersey (27), New York (19), Pennsylvania (1) and Rhode Island (1). Thirty-seven horses survived the infection and 23 (38%) died or were euthanised. In Connecticut, 4 horses recovered and 3 horses were euthanised (43%). In 2001 over 400 clinical cases of WNV infection in horses from 19 states were reported. Eleven Connecticut horses had clinical signs of disease, seven recovered and four d
