March may be the time of year when your winter show season is culminating or you could just be getting back to regular schoolings after a couple of low-key winter months. Either way, it is time to consider your dressage horse’s spring shots: immunizations that will protect your horse and support his health throughout the coming months. A review of the what, why and how of equine immunizations can help you ensure your horse is receiving the vaccinations he needs in an optimal way.
What Vaccines Does Your Horse Need?
Dr. Nancy Loving of Boulder, Colorado, is the author of the comprehensive equine health care guide All Horse Systems Go, and four other books. Loving, who has competed in dressage, eventing and endurance riding, says routine vaccinations are vital to ensuring a horse’s good health. According to Loving, core vaccines recommended by the Association of Equine Practitioners (AAEP) to be given annually include Eastern and Western equine encephalitis, West Nile virus, tetanus and rabies. Respiratory vaccines (flu and rhino) are important for horses congregating with numbers of other horses at shows, clinics, travel and on the farm.
Dr. Grant Rezabek is the chair of AAEP’s Infectious Disease Committee (IDC), the group responsible for developing and maintaining AAEP guidelines related to vaccines. Rezabek, who is also the serology section head and equine program coordinator at Oklahoma Animal Disease Diagnostic Laboratory, explains that the IDC is composed of equine veterinarians from a broad spectrum, including university systems, diagnostic laboratory systems, private practice and industry. According to Rezabek, the AAEP’s published guidelines require update/re-evaluation every three years. Decisions regarding changes to the vaccination guidelines are based on peer-reviewed publications, he says. “If information is published that suggests changes are necessary, the guidelines can be amended at any time. For example, there have been a few recent papers published that suggest immunity to equine herpesvirus by some vaccination protocols may be more long-lived than initially thought. Those publications will be evaluated by the IDC this year.”
Loving points out that horses participating in USEF events must have current influenza and rhinopneumonitis boosters in order to be admitted to show grounds. Upon the request of show officials, the person responsible for the horse must produce evidence that these vaccinations have been administered within the previous six months. Most commonly, this takes the form of documentation from a veterinarian affirming that the horse has been vaccinated, with which vaccines and on what date. FEI horses are required to receive annual influenza virus boosters, which must be documented on the horse’s FEI passport. Loving advises that horses who attend clinics and shows, or travel a lot in general, receive flu-rhino boosters twice annually.
The AAEP provides vaccination guidelines for adult horses through its website, including those risk-based vaccines that go beyond the core recommendations. According to its site, use of these vaccines may vary between individuals, populations and/or geographic regions. AAEP suggests consulting with a veterinarian about whether a horse should receive the following risk-based vaccines: anthrax, botulism, equine herpesvirus (EHV), equine viral arteritis (EVA), influenza, Potomac horse fever (PHF), rotavirus and strangles. Several of these vaccines are administered quite commonly, though frequency and recommendations can vary and may be especially applicable to horses who travel often or are used for breeding purposes. For example, broodmares may receive the EHV vaccine more regularly than other equine populations, but other vaccines (such as anthrax) can be contraindicated for pregnant mares. Likewise, the PHF vaccine may be recommended for horses living in or traveling to the Mid-Atlantic region of the U.S. or other geographic regions where the disease has occurred, but may be deemed unnecessary in other areas of the country where the disease has not appeared.
Rezabek stresses the importance of consulting a veterinarian and being aware of current government regulations when making decisions regarding the administration of risk-based vaccines. For example, according to Rezabek, EVA is not a foreign animal disease in the USA, but it is regulated. “The EVA vaccine will produce a life-long antibody response that is a complicating feature with respect to regulations,” he says. “If this vaccine is used, most breed registries request that the horse’s papers be updated to reflect this. This is not a vaccine that any owner should consider without very careful evaluation of risk/need and consultation with their veterinarian and state/federal regulatory folks.”
Loving puts it simply: “Vaccines for horses are well known to provide great protection against serious and potentially fatal diseases. The benefits of vaccinating any age horse significantly outweigh any mild adverse effects that might occur, like transient muscle soreness, not feeling quite right or reduced appetite—none of these signs last more than a day or two in most cases.” In addition to being required for travel and competition, regular vaccination helps to ensure that horses will not have to suffer through preventable illnesses. “If you have ever seen a horse die of tetanus, encephalitis, West Nile virus or rabies, you wouldn’t think twice about vaccinating annually for these diseases,” she says. The respiratory diseases (influenza and rhinopneumonitis) are not necessarily fatal but can elicit serious consequences like chronic inflammatory airway disease that has an effect on performance along with being detrimental to a horse’s overall health. Vaccinating not only keeps one’s own horse safe, but helps to prevent the spread of communicable diseases.
According to Loving, the high benefit and low risk of regular vaccinations extend to the senior horse population, including those affected by Cushing’s disease (pituitary pars intermedia dysfunction or PPID). Though individual horses with PPID may demonstrate increased sensitivity to vaccines, current research shows that these horses can still produce antibodies from vaccines and thus, should still receive vaccinations under the direct care and at the discretion of a veterinarian. In fact, Loving emphasizes: “Vaccines must be kept up on an annual basis for older horses particularly since they are more susceptible to disease than their younger counterparts.”
Rezabek states, “It is my opinion that vaccination benefits always outweigh any potential risk. Intended use, age and breed have all been proposed variables to consider regarding vaccinations/boosters. However, regardless of conditions and what they do for a living, all horses can be exposed to the following: tetanus, rabies and mosquito-borne disease [EEE, WNV].” He acknowledges that there are certainly potential side effects of vaccinations, including possible local swellings and, rarely, systemic reactions. However, he is quick to point out that according to U.S. Department of Agriculture reporting data, reactions are extremely rare.
How to Vaccinate Optimally
Veterinarians and the person responsible for the horse’s daily care can take simple steps to help optimize the vaccination process, reducing the chances the horse will experience discomfort. Rezabek points out: “It is generally recommended to monitor animals following vaccination and give them a day off from work to avoid complications.” For her part, Loving advises that a horse with a known sensitivity to a certain vaccine could be pre-medicated with a nonsteroidal anti-inflammatory drug (otherwise known as an NSAID, with common examples including bute and Banamine). She says this extra precaution can help to eliminate or greatly minimize the adverse reaction.
Typically, equine vaccines are administered intramuscularly (IM). The only common exception is the influenza vaccine, which may be administered via the nasal route, provided the vaccine is approved for that mode of administration. Loving explains that the cold-adapted strain used in the intranasally (IN) administered influenza vaccines is a modified live virus that can replicate at the cooler temperature of the upper respiratory tract. This enables the nasal mucosa to develop an effective immune response that stops flu at its normal site of infection, the nasal cavity. The AAEP has determined this vaccine to be safe and effective. However, according to Loving, “Many veterinarians prefer using IM products primarily because many horses object to having a cannula stuck up their nose, while a shot in the muscle is usually fairly quick and easy. One of the IN flu manufacturers has recently developed an applicator that should improve horse cooperation with the IN procedure.”
Though individuals who are not licensed veterinarians can opt to purchase and administer vaccines to horses, Loving emphasizes the many advantages of having a veterinarian vaccinate your horse, including assurance of proper handling of the vaccine, knowledge of which vaccines to give and when and implementation of best practices and product, which can help alleviate a reaction to the shots. Additionally, should a horse have an adverse reaction from the administration of a vaccine and then require additional medical care, some insurance policies will cover the additional care only if the vaccine had been administered by a licensed veterinarian.
“Horse owners should not be lax about having vaccines administered every year to maintain good protective immunity,” Loving says. In addition, quality nutrition is important as well as implementation of regular deworming schedules based on once- or twice-yearly fecal egg counts. Rezabek agrees: “Vaccination remains the cheapest and most efficient protection for horses against diseases known to be circulating in their environment. It is a simple and efficient method to ensure health and longevity.”