The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
Issue link: https://thehorse.epubxp.com/i/636486
18 TheHorse.com THE HORSE February 2016 remains an important (and deadly) viral disease. Infected wildlife can transmit rabies to horses either through a bite or via saliva coming in contact with a horse's wound or mucous membranes. Unlike dogs, most horses suffer from the "dumb" form of rabies rather than the "furious" form that Stephen King has forever burned into millions of Americans' memories with the thriller Cujo. "All mammals are sus- ceptible to the rabies virus, but since the elimination of ca- nine rabies from the United States back in the 1970s, the number of domestic animal cases has declined steadily," says Jesse D. Blanton, MPH, epidemiologist at the Centers for Disease Control and Prevention, in Atlanta, Georgia. "None- theless, rabies remains an important dis- ease in wildlife, including foxes, skunks, raccoons, and bats." In a 2014 Journal of the American Veterinary Medical Association article, Blanton and colleagues reported that in 2013, veterinarians diagnosed 31 cases of rabies in horses and mules—significantly fewer than the 47 cases reported in 2012. By the end of 2014 that number had dropped again to 25. "Over 5,300 cases of rabies in wildlife were reported in 2013, and many of those occurred in regions of the United States where horse populations are concen- trated, predominantly the Northeast," Blanton says. "Vaccination of domestic animals is a critical and cost-effective method of preventing rabies in domestic horses, especially because it is essentially impossible to prevent wildlife like bats, raccoons, and skunks from getting into your pastures at all times." The Winged Assassin Your usually steady steed is weaving around his field and can't seem to keep his feet underneath him. You've also witnessed him pressing his head into the fence rails. You've seen a few dead birds on your property lately, but figured they'd just hit a window. There have been so few reported West Nile virus cases in horses over the past few years—only 181 in 2015, compared to more than 15,000 cases in 2002—you didn't consider West Nile virus a real threat anymore. When was the last time you vaccinated your horses against it? Many mammals are susceptible to West Nile virus (WNV), but horses seem particularly so. As described in detail in our WNV special feature (TheHorse. com/35412), vaccination is extremely ef- fective in preventing this mosquito-borne disease—yes, this winged assassin is a tiny buzzing arthropod. "Like rabies, it is very important to remain vigilant with vaccination against preventable diseases," says Angela M. Pelzel-McCluskey, DVM, equine epide- miologist from the Surveillance, Pre- paredness, and Response Services of the USDA's Animal and Plant Health Inspec- tion Service. "Even if those diseases are not particularly common in your area, not vaccinating has unimaginable repercussions," including death. Veterinarians also advocate standard mosquito-control practices, such as fly masks and sprays and strategic turnout schedules (as night comes mosquitoes pose the greatest risk to horses), but we all know it is extremely difficult to fight every bite, which leads to our next topic. The Stranger in the Night A beautiful summer day has come to an end. As the sun sinks lower in the pink- and orange-hued summer sky, you dash out to get a quick ride in before dark. Your mare, who usually nickers a warm greet- ing, is standing morosely in her stall, head between her knees. It's a little dark, and as you head in for a closer look, you notice she hasn't touched her hay all day. West Nile virus is only one of several mosquito-borne encephalitides that affect horses. Other examples include Eastern, Western, Venezuelan, and St. Louis encephalitis viruses. Each results in clinical signs similar to West Nile virus: fever, depression, gait abnormalities, and neurologic deficits. Many infected horses also have signs (difficulty swallowing, gait abnormalities, recumbency, fever) that re- semble those caused by rabies. So always use caution and consult your veterinar- ian before handling a horse with clinical signs consistent with neurologic disease. Also like WNV, these encephalitides are largely preventable with vaccination. According to the American Association of Equine Practitioners, the mortality rates can range from 50-90%, and affected horses that survive often have lingering neurologic and/or vision problems. The Barn Intruder Yet another wobbly, uncoordinated, weak horse stars in this scene. Unlike the previ- ous cases, this horse has a head tilt, dif- ficulty swallowing, and is circling around instead of trying to walk straight. The signs look somewhat like those of the encepha- litides, but your veterinarian suspects a different disease: EPM. INTERSPECIES THREATS Vaccination and insect control can help prevent potentially deadly mosquito-borne diseases. Wildlife can transmit rabies to horses via bite or saliva. In 2014 there were 25 reported rabies cases in horses.