Biosecurity and Health Committee
Protocol for the Management of Rabies in Horses

Table of Contents

1. Disease Information
2. Human Health Risk Data
3. Horse Health Risk Data
4. Ecology Information
5. Prevention
6. Regulatory Information
7. Committee's Recommendations
8. More Information

Section 1: Disease Information

Rabies is a sporadic, but highly fatal, zoonotic disease caused by a virus (Lyssavirus). It persists in Ontario wildlife, primarily in the red fox and striped skunk. All warm-blooded animals can be infected with rabies but it is most often transmitted in Canada by foxes, raccoons, skunks and bats. Foxes, rats and coyotes are extremely susceptible; cattle, rabbits, and cats are highly susceptible; dogs, sheep and goats are moderately susceptible; and opossums little, if at all. The virus is almost always spread by saliva from the bite of an infected animal. In addition, but more rarely, rabies can be spread when virus from saliva is introduced into open cuts or wounds, or comes in contact with a mucous membrane in areas such as the mouth, nasal cavity, or eyes. Cases of fox-strain rabies have dropped dramatically across Ontario due to rabies control measures that were implemented in 1989.

Section 2: Human Health Risk Data

Rabies affects both animals and humans. Since 1924, twenty-three human rabies cases have been documented in Canada. Nine of these were associated with being bitten by bats. Rabid horses pose a serious threat to humans. A man in Ontario was killed by a rabid horse in 2002.

Section 3: Horse Health Risk Data

Horses of all ages are susceptible to rabies. Horses are often exposed because they are curious creatures. They are apt to investigate a wild animal that is acting strangely and may be bit on the muzzle, face and/or lower legs. Clinical signs are highly variable in the horse and may be very non-specific, particularly early in the disease. The disease usually progresses to death in 4 to 5 days, although some horses will survive up to 15 days. The "furious form" was noted in 43% of rabid horses and clinical signs in some of these animals initially appeared as the "dumb form." The paralytic form was not observed. Horses that develop the "furious form" show excitement, become vicious, bite, kick, exhibit blind staggers, suddenly fall and may chew themselves or foreign objects.

Section 4: Ecology Information

There are three different strains of rabies in North America, which are differentiated by their carrier species. The three strains include Arctic fox, raccoon and bat rabies. There are no differences between the strains as far as their ability to kill their carrier species, other animals and possibly humans. The disease persists in wildlife populations throughout the United States, Canada, Mexico, and other parts of the world. Wildlife infected with rabies may show no fear of man, be aggressive, or be incoordinated.

Section 5: Prevention

There is no effective treatment for rabies. Once clinical signs appear, rabies is almost always fatal. Therefore, it is best to prevent exposure to the virus. If a person is bitten by an animal, wash the wound or exposed surface with soap and water, remove clothing that may be contaminated, contact your doctor immediately or go to the nearest hospital emergency department.

Two inactivated (killed) rabies vaccines are marketed in Canada, Rabvac™ 3 (Wyeth) and Merial® Imrab® 3 (Merial).

• Foals born to vaccinated mares, should receive the first dose no earlier than 6 months of age, followed by a second dose 4 to 6 weeks later, a third dose at 10 to 12 months of age, followed by annual revaccination.
• Foals born to non-vaccinated mares should receive the first dose of vaccine starting at 3 to 4 months of age, followed by a second dose 1 month after the first, a third dose at 10 to 12 months of age, and followed by annual revaccination.
• Merial recommends that Merial® Imrab® 3 be given by either intramuscular or subcutaneous injection. Wyeth recommends that Rabvac™ 3 be administered by intramuscular injection only.
• Neither vaccine is labeled for use in pregnant mares but prepartum vaccination 4 to 6 weeks prior to foaling is recommended.
• Rabies vaccine can only be sold to and administered by a licensed veterinarian.
• Do not use modified live rabies vaccines in horses.
  

Section 6: Regulatory Information

Rabies is a reportable disease. If an animal is suspected of being rabid or a person thinks that their animal(s) has been exposed to rabies, he/she is required by law to report it. Call your nearest office of the Canadian Food Inspection Agency (CFIA), which is listed in the blue pages of the phone book (Guelph 519-837-9400). An inspector from the agency will investigate all calls. When a human is bitten by an animal, the local health unit must be notified. Show/racetrack organizers should ensure that all horses that can come in contact with the public have been vaccinated in the past 12 months.

Committee's Recommendations

• It is recommended that all horses be vaccinated for rabies annually.
• Be a responsible pet owner; vaccinate all cats, dogs and horses under your care for rabies.
• Stray animals, with unknown vaccination histories, should be removed from the premises.
  

More Information