That's understandable, I wouldn't put him under again either. A Newf I know of was put under to get her hips x-rayed and actually died on the table. Luckily when they stopped the anaesthesia, she woke up and they never tried agian since.
Stunning boxers! I especially love the brindle colour on them. Is that called tiger brindle?
Also, i really think they look the part with their ears cropped, but here in the UK it's banned so i never get the chance to see boxers like that. They've also banned docking tails here too, are some boxers born with bobbed tails or will i be seeing a lot more (silly looking) long-tailed boxers about?