West Nile virus is transmitted to horses via bites from infected mosquitoes. | Photo: iStock

The Delaware State Veterinarian’s Office announced Oct. 30 that it has confirmed two more cases of West Nile virus (WNV) in horses in that state. There are now five confirmed cases of WNV in Delaware horses for 2018.

The fourth WNV case was identified in a yearling Standardbred filly residing in Kent County. The filly received veterinary care for loss of limb control and buckling over in the front limbs which began on Oct. 11. Her clinical signs progressed to recumbency (inability to rise), muscle twitching (fasciculation), and stupor, and she was euthanized on Oct. 15. She had not been vaccinated against WNV. The University of Pennsylvania College of Veterinary Medicine New Bolton Center’s Clinical Pathology Laboratory reported positive WNV results on Oct. 19.

The fifth infected horse is a 6-year-old Belgian mare, also residing in Kent County, who was evaluated by a veterinarian for whole body stiffness and soreness, along with abnormal mentation (aggression, in this case) which developed on Oct. 12. Diagnostic specimens were submitted to the National Veterinary Services Laboratory, in Ames, Iowa, confirmed the diagnosis on October 23. The mare was not vaccinated against WNV. She was treated supportively and her condition was improving as of Oct. 18