I work as a Paramedic and myself along with a few others at work finally convinced our agency to purchase pet masks. I just used one of these.

We had a call for a house fire on Thursday night. A firefighter brought a dog that was found hiding in the closet. The dog was lethargic (weak) and wasn't fighting. I figured give it a shot. Someone called a local vet. While the vet was on their way, we hooked the dog up to our oxygen with the pet mask. Within probably 10-15 minutes, the dog started having more activity but was still just laying there. His breathing improved dramatically.

The vet told us if we didn't put the mask on and give him oxygen, the dog wouldn't of lived much longer.

Here is a picture of an old coworker of mine treating a dog from a house fire a while back

http://i.imgur.com/BBXMf.jpg