Kinds of Rabies Vaccines

If you’ve seen the movie “Old Yeller,” then you know how devastating rabies can be if a beloved pet becomes infected. Thankfully, we live in a time and place in which vaccinations are readily available to prevent such a tragedy. Once rabies symptoms appear, it’s too late to help, and the illness is fatal. This is why it’s important to vaccinate your pets against this illness as early as possible.

Rabies is a virus that can infect any species of mammal, including companion animals and humans. It’s highly contagious and typically transmitted from animal to animal through bite wounds. Once bitten, the virus travels up the nervous system until it eventually reaches the brain. Symptoms can take weeks or months to appear. Symptoms of rabies include aggression, extreme loss of energy, seizures and excessive drooling or foaming at the mouth.

Two types of rabies vaccines are given to pets. Puppies are usually given killed rabies vaccine, which uses a dead virus, when they’re between 16 weeks and 4 months of age. A booster shot is required one year later. Adult dogs whose vaccination history is unknown are given a similar regimen. After the initial inoculation, the killed rabies vaccine need only be given to adult dogs every three years for effectiveness, although some states require that it be given annually.

The other types of rabies vaccines for animals is live-modified or recombinant-rabies vaccine, in which the virus is alive but altered so that it stimulates the immune system to increase immunity against the virus. In recombinant vaccines, this alteration is done at the genetic level. This vaccine is typically given to cats and other animals, and a booster shot is required annually to maintain effectiveness, regardless of state law.

Unless planning to be in a high-risk situation, such as handling unknown animals or travelling to a part of the world where rabies is still rampant, humans are usually vaccinated for rabies only after they have been bitten by an animal who is possibly infected. If this happens, you should go to a hospital emergency room immediately, where you will be injected with the human rabies immune globulin (HRIG) in and around the bite area. Afterwards, you’ll receive one of the two rabies vaccines that have been approved for human use by the Food and Drug Administration -- the human diploid cell vaccine (HDCV) and the purified chick embryo cell culture vaccine (PCECV). For both vaccines, a regimen of four doses must be given over a two-week period.