AAEP - 2012 Principles of Vaccination
A “standard” vaccination program for all horses does not exist. Each individual situation requires evaluation based on the following criteria:
- Risk of disease (anticipated exposure, environmental factors, geographic factors, age, breed, use, and sex of the horse)
- Consequences of the disease (morbidity/mortality, zoonotic potential)
- Anticipated effectiveness of the selected product(s)
- Potential for adverse reactions to a vaccine(s)
- Cost of immunization (time, labor and vaccine costs) vs. potential cost of disease (time out of competition; impact of movement restrictions imposed in order to control an outbreak of contagious disease; labor and medication if, or when, horses develop clinical disease and require treatment, or loss of life.)
Clients should have realistic expectations and understand that:
- Vaccination alone, in the absence of good management practices directed at infection control, is not sufficient for the prevention of infectious disease.
- Vaccination serves to minimize the risks of infection but cannot prevent disease in all circumstances.
- The primary series of vaccines and booster doses should be appropriately administered prior to likely exposure.
- Each horse in a population is not protected to an equal degree nor for an equal duration following vaccination.
- Protection is not immediately afforded the patient after administration of a vaccine that is designed to induce active immunity. In most instances, a priming series of multiple doses of a vaccine must be administered initially for that vaccine to induce protective active immunity.
- All horses in a herd should be vaccinated at intervals based on the professional opinion of the attending veterinarian.
- A properly administered, licensed product should not be assumed to provide complete protection during any given field epidemic.
- Although rare, there is potential for adverse reactions despite appropriate handling and administration of vaccines.
© Copyright AAEP 2012
After receiving a vaccine(s) intramuscularly, some horses experience local muscular swelling and soreness or transient, self-limiting signs including fever, anorexia and lethargy. Severe reactions at sites of injection can be particularly troublesome, requiring prolonged treatment and convalescence. Systemic adverse reactions (such as urticaria, purpura hemorrhagica or anaphylaxis) can also occur. Other systemic adverse reactions have been anecdotally reported [e.g., colic, immune-mediated hemolytic anemia, a condition in which there is an accelerated destruction and removal of red blood cells, added by CMS].
Veterinarians should report adverse reactions to the vaccine’s manufacturer and/or the USDA Center for Veterinary Biologics at 1-800-752-6255 or through the agency’s Web site.
Vaccine lot and serial numbers should be noted in horses’ vaccination records. The ability to provide this information when reporting an adverse reaction will facilitate an investigation.
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. Some veterinarians may elect not to vaccinate horses within 3 weeks of international shipment.
Injection site selection should include consideration of potential adverse reactions. Injection in the gluteal muscles/hip region is not recommended, as gravitational drainage along fascial planes can be obscured. Should an abscess develop, considerable tissue damage can occur and result in eruptions in undesirable locations with lesions that require prolonged time to heal.
The interval from vaccination to scheduled event or a predictable risk of exposure should be sufficient for:
- Generation of a protective immune response to vaccination.
- Recovery from unexpected adverse vaccination reactions that might otherwise interfere with the horse’s performance or health prior to, or during shipment.
- Administration of vaccines containing multiple antigens/adjuvants at the same time may increase the risk of adverse reactions.
- Safety and efficacy data are not available regarding the concurrent use of multiple vaccines.
- Administration of MLV and killed vaccines in the same location is discouraged as adjuvants may inactivate the MLV.
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.
AAEP – 2012 core vaccines for horses
The AVMA defines core vaccinations as those “that protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.” The following equine vaccines meet these criteria and are identified as ‘core’ in these guidelines: Tetanus, Eastern/Western Encephalomyelitis, West Nile Virus, Rabies.
The AAEP considers the following to be RISK-BASED VACCINES
These are vaccinations included in a vaccination program after the performance of a risk-benefit analysis. The use of risk-based vaccinations may vary regionally, from population to population within an area, or between individual horses within a given population. Disease risk may not be readily identified by laypersons; it is important to consult a veterinarian when developing a vaccination program.
- Equine herpesvirus (Rhinopneumonitis)
- Equine Viral Arteritis
- Equine Influenza
- Potomac Horse Fever
- Rotaviral Diarrhea