I too would give it another week but if you don't receive one, I agree, that is very disappointing. Puddy was back and forth from the hospital so many times (and for years I'm assuming), especially in the last few months. And the fact that you have spent 30,000 at one hospital over the years should have you at the top of the client list. A wing of the hospital should be named after Puddy!!
I sent a thank you card to both the clinics that dealt with Tiger and received theirs in the same week. Maybe you could send one and say something like "Just wanted to say thanks for everything. I received a very kind card from the other hospital that hardly knows me. It meant alot. Perhaps yours got lost in the mail?"
I do hope that you get a card soon. I think for the most part, it is standard for clinics to send them out and because Puddy was such a regular customer with a mom who spared nothing to help her, it would amaze me if they didn't send one. Maybe it was an office slip up, one receptionist thought another had handled it kind of thing but it should be brought to their attention in a few weeks if nothing happens.