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Vaccination Information

By April 2, 2019 No Comments

We have been getting lots of questions about vaccination protocols lately. The following is adapted from the American Association of Equine Practitioners.

Vaccine reactions/Adverse Effects: After receiving a vaccine intramuscularly, some horses experience local muscular swelling and soreness or transient, self-limiting signs including fever, anorexia and lethargy. Adverse reactions are not always predictable and are inherent risks of vaccination. Therefore, it is recommended that horses not be vaccinated in the 2 weeks prior to shows, performance events, sales or domestic shipment. Usually a dose of Banamine or other anti-inflammatory can resolve these issues.

Vaccines should always be administered by, or under the direct supervision of, a veterinarian, as the possibility of adverse reactions (including anaphylaxis) exists with the administration of any vaccine.

Core vs. Risk Based Vaccinations:

Core vaccines include Eastern and Western equine encephalomyelitis (EEE/WEE),Medications west Nile virus (WNV), tetanus and rabies and should be administered to all horses at least annually following an initial two-to-three-dose series. The initial dosing series frequency is based on the horse’s age at the time your veterinarian administers the initial vaccine series. Ideally, the veterinarian administers core vaccine boosters in the early months of the year (spring in the Northern Hemisphere) so horses will have mounted a robust immune response by the time exposure to the pathogen is likely to occur.  Transmission of insect-vectored diseases is linked to climate and season. This is why we want to vaccinate early in the year to allow the horse to produce antibodies that will provide protection later in the year when potential virus-carrying mosquitoes are in highest numbers.

Risk-based vaccines protect against a variety of diseases that can affect certain horses but are not necessarily a risk for all horses and are less likely to result in death. Risk-based diseases include viral respiratory pathogens such as equine influenza (EIV) and equine herpesviruses-1 and -4 (EHV-1/4), also termed rhinopneumonitis. Horses that compete, travel and are exposed to horses from other farms are at a higher risk of coming into contact with these pathogens – this is why they are classified among the risk-based vaccines. When horses are infected with these pathogens, they can develop clinical signs of respiratory disease such as lethargy, high fever, mucoid (mucousy) nasal discharge and coughing.

Due to the severity of signs associated with viral respiratory disease, affected horses can be out of training for extended periods, from a few weeks to a month or more. Some horses that suffer from primary upper respiratory viral infection develop secondary bacterial infection of their lower airways, termed bronchopneumonia. Therefore, it is important to consider that performance horses might be exposed to viral respiratory pathogens and to implement proper precautions against disease, including good biosecurity and optimal vaccine protocols.