I have done mouth to nose resuscitation on my wifes cat.
He was a Birman about 18 years old , she had him before we met , and it took a very long time before he started to warm to me .
Anyway because he was quite old , his kidneys started to go and he got some sort of chest infection , we took him to the vet who prescribed some antibiotics.
They didn't really help much , he stopped eating and started to go down hill at a rate of knots , we nursed him as best we could and tried to get fluids into him , but on the Saturday night about 6:30 pm he stopped breathing .
I did resuscitation on him for about 30 seconds and the little old bloke revived for a few minutes , but it was to be short lived as he slipped away again.
I tried again but it was no good he was too far gone and he passed away on our kitchen floor.
At least he wasn't in pain anymore , we had him cremated and keep his ashes and picture on the mantle piece.
We like to think he's up there somewhere in animal heaven , young again and running around playing with all the other dearly departed pets.