It used to be that you were not supposed to get them sweated up for a week after their jags but it's not the case anymore, I think they switched from live virus vaccination to the alternative. You're best to ask your vet if you're not sure though.
I read something in a magazine that the vaccines used to be diluted, hence the advice not to let them sweat, but they are more purified now so it doesn't matter if they sweat or not.
That is my understanding but I may be way off and its not something I'd like to be wrong about. I would always ask the vet while they're doing it