These abscesses are generally not caused by infection, but by the body's over-reaction to the vaccine. Mild fever, decreased appetite and activity Mild fever, decreased appetite and depression may be observed for 1-2 days following vaccination, most commonly when modified live vaccines are used. Generally no treatment is warranted. Cats vaccinated with some Chlamydia vaccines may show weakness, lethargy, lameness, fever and loss of appetite for 1-3 weeks after vaccination. In some instances, medications such as corticosteroids may be used to help alleviate the symptoms.
Severe illness can occur if vaccines designed for intranasal use are accidently injected.
Severe reactions can also occur if any of a vaccine made for injection accidently enters an animal's eyes, nose or mouth. They may spread the vaccine-form of the virus to other animals through their coughing. Lameness Rarely, lameness can result from several different vaccinations. Kittens vaccinated with a modified live calicivirus vaccine may develop lameness within 3 weeks of the vaccination. Some kittens may also develop a fever and lose their appetite.