Unlike the ‘anti-vax’ movement among parents of small children, experts say most of the cases of horses going unprotected from common illness are not due to concerns about the vaccines’ side effects. The causes behind lapses in vaccine schedules are probably many and various. Rusty Ford, equine program director for the Office of the Kentucky State Veterinarian, believes many situations come down to two factors: strapped finances and a lack of education. Vaccines are one more expense to add to the cost of horse ownership of course, but rolling the dice with the horse’s immune system can prove more expensive if the animal contracts a serious disease. Ford believes many people just don’t understand how easily diseases like West Nile Virus can spread. “West Nile Virus hit Kentucky’s equine population in late summer/fall 2001 with eight horses being confirmed as affected,” Ford recalled. “The following year Kentucky reported 513 cases, of which 496 (97 percent) were not immunized.” Fortunately, horsemen responded to the outbreak quickly: In 2003, the prevalence dropped to 102 cases with 94 percent unvaccinated and then dropped to eight cases in 2004 and nine in 2005. It’s important to understand that the level of public awareness of illnesses like West Nile might wax and wane, too. Ford said that in 2006 the number of cases doubled to 18. Upon subsequent investigation, he found that none of those 2006 cases were up-to-date on West Nile Virus vaccines, and many of them were young horses with no prior history of immunization. Other experts say some people understand the severity of the diseases their horses are risking, but either can’t afford the shots or aren’t sure the vaccines are worth the cash. It’s true that none of the vaccines against common illnesses in horses (or any vaccine, for that matter) are 100-percent effective at preventing the disease in all animals, but owners should understand the immunizations provide a very good chance of keeping the animals healthy. “If they do become sick after vaccination, it is generally a much milder form of disease that they can recover from quicker than if they were not vaccinated,” said Dr. Leslie Easterwood, assistant clinical professor at Texas A&M University’s College of Veterinary Medicine. “That will result in lower costs and shorter recovery time for the horse.” Ford finds it helpful to compare the vaccines to a seatbelt. “Though a seatbelt will not keep you from being involved in an automobile accident, the benefit of wearing one is to minimize the impact or severity should you be involved in an accident,” he said. In an effort to save money, some owners may be inclined to take a wait-and-see approach to vaccinating. That is also a mistake, according to Ford. In the seatbelt analogy, that’s like clicking it after the accident. For owners who are concerned about the action of vaccines, it may be helpful to explain the differences between killed vaccines and modified live vaccines. The former has been used for many years but the latter are usually less expensive to make and recent research suggests they could be somewhat more effective at immunization. It’s believed that this difference in efficacy is due to killed viruses triggering a response predominantly in antibodies, while live viruses infect host cells and trigger a response in cytotoxic T-cells in an adaptive immune response. No matter which kind of vaccine is used, horse owners should understand that their horse will need vaccines more often than humans receive boosters because they are unable to control their environments the way we can. “Horses are generally vaccinated more frequently than humans because of the diseases that we vaccinate for in horses,” Easterwood said. “For example, rabies is a vaccination that we recommend be administered yearly for horses. Most people are not vaccinated for rabies unless they work in a high-risk field, such as veterinary medicine. Horses live outside where they can encounter skunks, and they have no logical thinking to tell them that skunks could be dangerous.” It may also be helpful to advise concerned owners of the best ways to monitor a horse after vaccination. Easterwood said serious side effects like allergic reactions are very rare (and that they are a risk with any substance given to a horse); more commonly, owners should watch for soreness and swelling at the injection site, as well as any signs of depression or fever in the first 48 hours after a vaccination. In the case of horses that become especially anxious about injections, or who are doing work that uses a lot of neck muscle, it may be beneficial for them to get a light day or day off from work after having their vaccines to allow soreness to dissipate. For additional information and suggested vaccine schedules, refer to the American Association of Equine Practitioners’ website.
