Rabies | AAEP

Background:

Rabies is an infrequently encountered neurologic disease of equids. While the incidence of rabies in horses is low, the disease is invariably fatal and has considerable public health significance.

The rabies vaccine is a core vaccine that should be administered to all equids annually.

Exposure occurs through the bite of an infected (rabid) animal, typically from a wildlife source such as raccoon, fox, skunk, or bat. Rabies is endemic in every state in the United States (except Hawaii), whether terrestrial or in the bat population. Bites to horses occur most often on the muzzle, face, and lower limbs. The virus migrates via nerves to the brain where it initiates rapidly progressive, invariably fatal encephalitis.

Vaccines:

Several vaccines are licensed for rabies prophylaxis in horses. All are inactivated tissue culture -derived products. Some are labeled for mixed animal species and some for horses only. They are available as a monovalent vaccine or in combination with other antigens. Rabies is an excellent immunogen and these vaccines induce a strong serologic response after a single dose and are licensed for 12-14 months of protection.

Vaccination Schedules:

Vaccination by a licensed veterinarian may be required by state law for rabies vaccine to be considered valid. The majority of the states require rabies to be administered by or under the supervision of a licensed veterinarian.

Unvaccinated adult horses: Administer a single dose and revaccinate annually.

Vaccinated adult horses: Revaccinate annually.

Pregnant mares: Currently one vaccine (a combination product containing all core antigens) is labelled safe for use in pregnant mares. While other commercially available monovalent vaccines are not specifically labeled for use in pregnant mares, they have been widely used in this population. Mares may be vaccinated before breeding or 4 to 6 weeks before foaling.

Foals and Weanlings – of unvaccinated mares:

Administer 1-dose at 4-6 months of age (refer to manufacturer label guidelines). Annual revaccination is recommended.

Foals and Weanlings – of vaccinated mares:

Administer a 2-dose series, with 1st-dose at 4-6 months of age (refer to manufacturer label guidelines) and 2nd-dose at 4-6 weeks after the 1st-dose. Annual revaccination is recommended.

Note: The recommendation for a 2-dose initial series in foals from mares vaccinated with rabies within the year prior to foaling is to address the potential for maternal antibody interference.

Rabies products are efficacious for a least 12 months based on efficacy studies with naïve foals.

Horses exposed* to a confirmed rabid animal:

Horse currently vaccinated against rabies by a licensed veterinarian with proof of administration of a USDA-approved rabies vaccine: Immediate revaccination by a licensed veterinarian and observation for number of days as directed by state public health officials.

Unvaccinated horse: Contact your state’s public health officials immediately as they will have established requirements and conditions for the monitoring and/or disposition of exposed, unvaccinated animals. These officials will dictate what options are available for the exposed horse. These options may include isolation for up to six (6) months and immediate post-exposure immunization of the horse. Alternatively, the horse can be euthanatized immediately.