http://www.rabieschallengefund.org/about-the-rcf/about-the-rabies-challenge-fund
I really don't know and don't have time to research now. You might try looking up some info on the Net like rabies shots and seizures in dogs.
Years ago I knew a woman that had a kennel of show Yorkies. Her 3 or 4 year old Champion male died after a rabies shot. However, I have been around a lot of dog people fir many years and that is the only time I heard that. Reactions are not all that uncommon with the booster vaccines, I have dealt with those issues.
When my dogs got older, and my Vet agreed, I stopped the shots but they were just at home or our neighborhood so not at high risk.
Hope your dog will be ok.
You might look into the need for them. According to the things I have read on line many times these shots are not needed nor must one have them. You can also get a letter from your vet exempting them if they have had a bad reaction. I know we will never get another rabies shot.
It seems more than a coincedence that the seizures started up right after the shot.
Our dog is 13 also, and I have discontinued all shots except rabies. You make me wonder if I should stop the rabies also.