Part of the reason I'm agitated with this vet is that he's almost a month late for several shots (including his heartworm shot) and I never got a call to remind me to schedule an appointment even though I pay monthly for a plan...
Wow. That is not good. You don't want to mess with heartworm. And no, your vet should not be taking your dog into the back room for shots. What happens if you ask him to give the shots in front of you?