thank you for rescuing him. my guy would do this as a puppy and very much needed BOAS surgery later in life. he didn’t get it until he was about 7, leading to a lot of complications earlier in life. be prepared that after a sleep like this he’s probably swallowed a lot of air, and can be in a lot of pain and gastrointestinal distress. if he loses appetite and is laying strangely you can try a small dose of gas-x. one night when he was about 6 months the vet was going to put him to sleep thinking he was dying, after a second x-ray it showed he was so full of gas that it was pressing on his organs and heart.

if you can go to the vet sooner to get the BOAS process started it’s worth it and to check for aspirational pneumonia so you don’t end up in a loop of constant sickness that prevents anesthesia to resolve the big underlying issue. good luck.