According to VetInfo, a possible side effect of the rabies vaccine is anaphylaxsis, although this happens very rarely. An allergic reaction or cancer located at the injection site is another potential side effect. Behavioral side effects include sudden aggression, anxiety and destructive or compulsive behavior. Other side effects are seizures, muscle weakness, digestive issues and epilepsy.
VetInfo describes anaphylaxsis as a potentially fatal condition in which an animal goes into shock characterized by respiratory and cardiac failure. Onset is between a few minutes and 24 hours after the rabies vaccine. To prevent fatality, epinephrine must be given upon onset. Signs of anaphylaxsis include vomiting, seizure, diarrhea, increased heart rate, weak pulse and facial swelling.
VetInfo warns that side-effects of the rabies vaccine can take up to a few months to appear and can range in intensity from mild to life threatening. Those getting the vaccination for a dog should be prepared to respond in an emergency situation. Seek medical attention, keep access to vaccination records, and refrain from giving multiple vaccinations with the rabies vaccine as the risk of a negative side effect increases with additional vaccinations. After the animal receives the rabies vaccine additional vaccinations should be delayed by a few weeks.