I don't know the side effects of an expired shot and don;t know if it is harmful or not but if some vet says expired shots are good enough to be given to my pup then i might consider changing the vet.
ETA: But that is just my opinion, I am a newbie and this is my second dog.
Robean Gyalchen Lamakhor.
Tyson GSD 09 JUNE 2013
Rusty BOXER 12 Jan 2009 to 25 Oct 2012