Adverse Reaction to Rabies Vaccine in Cats

Cats need to have a rabies vaccine to protect them, especially if they are outdoors and have the potential of having personal contact with other animals that could be affected with the rabies virus. In the United States, the number of reported rabies cases in cats exceeds the number of cases in dogs. Rabies is a major health concern since it is able to be passed between species and to humans. 

In most states, it is mandatory for your cat to have the rabies vaccine. Some counties allow for a three year vaccine to be given while others require a yearly vaccine. Be sure to research your county’s laws regarding vaccinations for your cat. If you are unsure about what vaccinations are required by law for your cat, contact your veterinarian for assistance.

Generally, if your cat has a reaction to the rabies vaccine it will be minor. There have been cases, though, where the reaction is life threatening. When your veterinarian administers the rabies vaccination to your cat, be sure to watch your cat closely for several hours for any signs of having an adverse or allergic reaction.

Your cat may exhibit mild signs of an adverse or allergic reaction to the rabies vaccine. Those signs generally lessen over a few days and then resolve. Your cat may also develop serious signs from their vaccine that will need veterinary intervention and treatment. If you notice any of these signs, mild or severe, contact your veterinarian for an immediate appointment. 

Signs of a mild reaction or allergy to the rabies vaccine in cats include:

• Vomiting
• Swelling at the injection site
• Pain at or near the injection site
• Fever (low grade)
• Diarrhea
• Appetite loss
• Lethargy
• Itching 
• Sneezing 

Signs of a serious reaction to the rabies vaccine in cats include: 

Vaccine Associated Fibrosarcoma

This is the development of a cancerous tumor at the injection site. The tumor can develop from a few weeks to a year after the vaccination has been given.

Organ Damage

The protein that is in the rabies vaccine can potentially damage your cat’s kidneys, liver and/or central nervous system. Organ damage can occur up to 45 days after the vaccination has been given. 

Anaphylactic Shock

Immediate veterinary care is required if your cat experiences anaphylactic shock, death can occur quickly without prompt treatment. While uncommon, signs of anaphylactic shock include facial swelling, difficulty breathing, coma, seizures, or death.  

An adverse reaction can occur when your cat is exposed to some form of allergen, in this case, something within the rabies vaccine, and its immune system begins attacking itself. 

Your veterinarian will begin their assessment of your cat by asking about your cat’s medical history including any recent vaccinations, diet changes or environmental changes. They will then conduct a physical examination. A urinalysis, fecal exam, complete blood count and biochemistry panel may be completed to rule out other possible causes of the adverse reaction.

Once your veterinarian has determined the cause of your cat’s reaction, they will discuss treatment options with you. Usually, mild cases will not require treatments unless it is an antihistamine and/or corticosteroid to stop itching or sneezing. Anti-inflammatories may be given to reduce swelling. 

If your cat has developed a more serious adverse reaction or allergy to the rabies vaccine, your veterinarian will need to administer treatments. These treatments will probably be supportive care in the form of intravenous fluid therapy, oxygen therapy and close monitoring of their vital signs. 

If your cat has gone into anaphylactic shock, emergency measures will need to be taken to keep your cat’s airways open so they are able to breathe. Oxygen support will most likely be necessary. Epinephrine will be given as well as antihistamines.

Your veterinarian can help you protect your cat from developing a serious rabies vaccine allergy, or another reaction once they know that your cat is sensitive to the vaccine.  If your cat has had a mild reaction in the past, it is important to mention that to your veterinarian.   Also, ask your veterinarian if three year rabies vaccine will suffice or if your county requires a yearly vaccine. 

Prior to giving the rabies vaccine, ask your veterinarian about administering an antihistamine to reduce the allergic reaction that your cat experiences if your cat has had any reactions in the past.