I did a search for you and came up with this:
http://www.dogs4dogs.com/JR_Articles/Rabies.html The rabies vaccine is the only legally-required vaccine for companion animals in the United States. It’s administered primarily to protect humans from their pets should those pets be bitten by rabid bats, coyotes, raccoons, foxes or other animals. This is all well and good EXCEPT that the vaccine is known to cause serious side effects, and even death, in cats and dogs.
Possible adverse side effects include, but are not limited to:
Aggression, destructive behaviors, separation anxiety and odd obsessive behaviors (like tail chasing and paw licking)
Autoimmune diseases, including organ disease, allergies and skin problems
Chronic digestive problems
Fibrocarcinomas at the injection site (particularly in cats)
Muscle weakness
Seizures and epilepsy
I'm sure that these side effects don't happen THAT often, but it's good to know to watch for signs...