Virginia is urging horse owners to check their animals' vaccination records after a horse in Loudoun County contracted West Nile virus and had to be euthanized.
The Department of Agriculture and Consumer Services says the 9-year-old Morgan Gelding is the state's first positive case of West Nile virus in a horse this year.
West Nile is commonly spread by mosquitoes infected with the virus.
For the vaccine to be effective, it must be administered properly several weeks before the horse is exposed to the virus. Other prevention measures include eliminating standing water in which mosquitoes can breed, using insect repellents and removing horses from mosquito-infested areas during the period from dusk to dawn.