From the Maryland Department of Agriculture:
WNV: A 2 year-old pony at a Frederick County farm is the state's first probable WNV equine case of 2011. The pony's onset was Sept. 26 and clinical signs included ataxia, depression, staggering, and muscle fasciculations. The pony presented with a mildly elevated temperature, which gradually decreased over the next few days. The pony had no prior vaccination history for WNV or EEE, but was previously vaccinated against rabies. No travel history was noted, although other horses did regularly come and go from the property. A serum specimen tested positive at 1:400 dilution via IgM-capture ELISA at the Virginia Dept of Agriculture Animal Health Laboratory. The pony was treated with Acyclovir, DMSO, and Marquis and has since made a nearly full recovery. No other illness was re-ported in other animals on the farm.
In addition to the probable equine WNV infection, Maryland has also reported: 19 human WNV cases, 17 WNV-positive mosquito pools (including 11 reported by the Department of Defense), six WNV-positive birds, and three mosquito pools positive for Cache Valley virus.
Even though West Nile has decreased in incidence, it is still with us, it is worth noting that the pony was unvaccinated.