In 1989, there were nearly a third more cases of rabies in cats than in dogs. Rabies is caused by a virus that attacks nerve tissue. Infected animals may withdraw and avoid contact with people and animals. Others become unnaturally aggressive and may attack. In North America, most rabies exists in wildlife, especially racoons, skunks, foxes, and bats.
Rabies is spread by bites or saliva of infected animals.
Therefore, an unvaccinated cat involved in a fight with a wild animal or with wounds from an unknown animal should be suspect for rabies. When rabies is diagnosed, animals must be euthanized. If humans are infected, they can be vaccinated successfully in early stages of the disease. Treatment, however, is unpleasant and costly. It's almost impossible to prevent exposure, so all cats should be vaccinated.