Ask a Dog Vet and Get Answers to Your Dog Health Questions
Hello. Thanks for the question.
The rabies vaccine we use in dogs is the same vaccine that we use in cats. Essentially what you're asking is whether a double dose of the vaccine is harmful. It can induce a pretty significant immune response in the dog. This may lead to a fever, lethargy and potentially allergic reaction signs like vomiting, diarrhea, facial swelling and hives.
If needed, a short course of steroids (Prednisone) and Benadryl can help blunt the response. You can give Benadryl at home at a dose of 1-2 mg per lb body weight. It can be given every 6-8 hours, as needed.
I hope this helps, let me know if you have any other questions.