I was thinking about this a little more--another reason not to be worried...
My future in-laws adopted a dog from the humane society that was supposedly a purebred Cairn Terrier (but I think it's really just obese Chihuaha with some sort of terrier thrown in), but the dog had just been spayed the day before. When they adopted it, she was the sweetest, calmest dog.
However, my fiance and I now refrain from calling it a "dog" because it is the meanest ANIMAL that anyone I know has allowed in their home. Stella will never be allowed to meet her sister in-law because they're close in size but IT would try to eat my poor Stella...just like it attacked the boxer down the street (that didn't go so well for her).
Long story short, I think they change immediately after surgery, but he'll be back to his happy self in no time
