What Are the Dangers of Giving Kittens Rabies Shots?

Many, though not all, municipalities in the United States require that all domestic cats be vaccinated for rabies, otherwise known as a "core vaccine." If a cat develops rabies--almost always by contact with another animal--it is generally fatal, as there is no known cure. So even if your local area doesn't require this by law, it's always a good idea for cat owners to ensure their pet's safety by having her vaccinated. There are risks involved in vaccinating kittens too soon after birth, however.

  1. Natural Immunity from Mom

    • Kittens receive natural antibodies from their mother through the colostrum--substances found in their milk--as they nurse. These maternal antibodies boost the kittens' immune system, thanks to their mom, and provide them with instant protection against many diseases and conditions. The antibodies, however, also negate the effects of vaccines, including the rabies vaccine. Vets thus refrain from giving very young kittens vaccines against most diseases until they've lost that natural immunity.

    Minor Side Effects

    • Modern vaccines pose few risks for nearly all animals, including cats, and are almost always preferable to the chance of exposing the cat to the rabies virus and compromising her health. However, as with human vaccines, the rabies vaccine does pose potential health risks and side effects, most of which are mild and will quickly pass. They include: mild to moderate discomfort at area of vaccination; mild fever; temporary lethargy; nausea and diarrhea; and diminished appetite.

    Serious Side Effects and Risks

    • Although more dangerous side effects are rare, cat owners should be aware of them in case their pet displays any of the symptoms after vaccination. Serious side effects include: loss of motor skills; kidney and/or liver damage; intense allergic reaction such as hives; tumors (known as "sarcoma") at the site of injection; and chronic lethargy lasting more than a day or two. If your cat shows any of these side effects following vaccination, including the milder ones, contact your vet immediately.

      To minimize the risks of your kitten experiencing adverse reactions after a vaccination, always inform your vet of any medications or treatments it may be undergoing that the vet is not aware of. In addition, if the kitten has demonstrated any changes in behaviors or habits, let the vet know as well.