Board of Health

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THE COMMONWEALT H OF MAS SACHUS ET T S EXECUTIVE OFFICE OF ENERGY AND ENVIRONMENTAL AFFAIRS Department of Agricultural Resources 251 Causeway Street, Suite 500, Boston, MA 02114 617-626-1700 fax: 617-626-1850 Original March 15, 2006 mcahill Revised January 16, 2009 pcabral Once A Three-year, Always A Three-year! -Rabies Vaccination Protocol For Dogs and Cats.

The Department of Agricultural Resources routinely answers questions regarding the appropriate timing of rabies vaccines for dogs and cats. The following is being distributed in an effort to ensure that all animals are vaccinated appropriately under the state law. According to Massachusetts General Laws, Chapter 140, section 145B, all dogs and cats 6 months of age or older must be vaccinated against rabies by a licensed veterinarian. Massachusetts Regulations, 330 CMR 10.02 and 10.03 specify the timing sequence the shots must be given in order for a veterinarian to issue a valid 3-year rabies vaccination certificate. There are many different rabies vaccines available on today’s market.

Those vaccines that are licensed for use in dogs and cats are approved as either 1-year vaccines or 3-year vaccines. Massachusetts requires strict adherence to a vaccination schedule before an animal may be considered vaccinated for 3 years. The first rabies shot in an animal’s life is always only good for one year. This applies regardless of whether a 1-year or a 3-year vaccine is used, or what the age of the animal is at the time of vaccination. Between 9 and 12 months after the first shot (not a day early, not a day late) dogs and cats should be given a second rabies vaccination.

These two shots together are referred to as the “primary series”. Unless an animal has completed its primary series, all rabies vaccinations given will only be considered good for 1 year. If a 3-year vaccine is used as the second shot in the primary series, the animal will be considered vaccinated for 3 years. Any animal that has completed its primary series will always be eligible for 3-year vaccinations (once a three-year, always a three-year!).

Even if an animal has not been vaccinated for many years, as long as the owner has vaccination certificates indicating that the animal has completed its primary series, a 3-year vaccination may be administered and a 3-year certificate issued. It is important to note, any animal that had never been vaccinated, or for those that had their last vaccination expire, the animal will not be considered legally vaccinated until 30 days after the rabies shot has been given.

Please feel free to contact Patricia Cabral at the Department’s Division of Animal Health should any questions arise. Ms. Cabral can be reached at (617) 626-1786, or by e-mail at