Can a dog's self esteem be affected after staying over night at the vet for surgery?

My dog had a submissive urination problem since he was a small puppy. We fixed it after 6 months of hard dedicated work. He went to the vet 1 month ago to get neutered, and as soon as he came back, the submissive urination started again. We have to start over from square one, and the urination is worse than ever. He is a 1.5 year old mastiff. I am wondering if maybe something happened to him while he was there to make him want to submit to us so drastically? Or the anesthesia changed his brain?? Lol, i know that sounds nutty, but I know that it is a risk for elderly people when they undergo surgery...and they suffer a form of dementia that their brain doesn't recover from due to the anesthesia sometimes. I mean, it was his first time away from home other than staying at his grandma's house, and i can understand his fear of waking up in a strange place, ( They said he displayed cage guarding when they went to take him to his surgery) which is something he has never ever done. Anyways, any input to understanding this odd change in behavior would be appreciated...I've only had a couple thoughts on it. It's upsetting to see 6 months of hard work go down the tube overnight...literally.