I'm sorry for your loss. The anaesthetic would not have made the tumors grow. A few minutes or hours is not enough time for significant growth to happen, anyway. That takes weeks, at the very least. It sounds more like the tumors just weren't causing any symptoms until the additional stress of the dental procedure overwhelmed the dog's reserves.
It is typical for dogs not to show symptoms until very late in a disease process. In the wild, to show weakness is to invite an attack by predators or even packmates. A wolf pack or wild dog pack will attack and drive away or sometimes kill a sick or elderly member, because that individual is a drain on the pack's resources. So dogs typically don't display symptoms of illness until they are completely unable to avoid doing so. Your dog had not reached that point yet.
I definitely wouldn't jump to the conclusion that the vet who did the pre-dental work-up is a negligent doctor, simply because of what happened here. After all, two other vets were just as shocked at the outcome as he was. If he were a bad doctor, the other two vets wouldn't have been shocked, because it would have immediately occurred to them that he must have missed something. The other doctors know who is competent. This sounds to me like just a tragic freak event.
There is a website, CanineCancer.com, that states that 25% of dogs that are diagnosed with lung cancer have no symptoms, and many of them have no abnormal values on routine blood tests. X-rays would have shown your dog's tumors, but there was no reason to do x-rays. A chest x-ray has never been a normal part of a pre-dental workup.
In regard to whether the doctor should have heard something abnormal when listening to your dog's chest before the procedure, possibly there was not anything obvious to hear. Even if he was a bit casual about the exam, which he might have been under the circumstances, it is hard to blame him. He had no real reason to suspect anything was wrong, and in fact he may well have been meticulous in his exam. Either way, he did not hear anything suspicious. If she was breathing easily, then that's probably what he heard -- breath sounds. What he was evaluating was whether she was breathing well enough to tolerate the procedure, and it seemed that she was.
As has been stated above, your dog would have become clinically ill at some point, and she would eventually have died from the cancer. The ultimate outcome would have been the same, but this was just such a shock. There was no time for you to adjust to the knowlege or to say goodbye. What happened is a terrible, painful thing, and again, I'm so sorry.
I don't have any answers to your questions, I'm sure others will. I would just like to say how sorry I am about your little dog, you must be in shock, never expecting an outcome like that. I would guess she had cancer long before the surgery, and the outcome would have been the same, with or without the surgery. I'm so sorry.
Yes shock. Her vet who did the dental is in shock. The vet that admitted her to the hospital is in shock. The vet who was there and put her to sleep at the hospital at 11:30 pm was in shock.
So very sorry.
I believe cancer has to grow over time to develop to the point it is life threatening. I believe there was nothing that could have been done to save the little girl.
I know she had a happy life with you, and for that she was fortunate.
I am so sorry you lost your sweet girl. It sounds like your Vet did the proper testing pre surgery. I can imagine how all of you were shocked as I would have been too. I am sure the cancer was there and it would have only been a matter of time before you noticed symptoms. Many of us have, unfortunately, had the unexpected happen but sometimes it is fir the best. At least you and she didn't have to suffer from a progressive cancer.
Again, so sorry for this sad outcome.
I'm so very sorry about your little dog. :-( I also understand the shock factor because I'm still in shock from losing my 9-year-old dog to hemangiosarcoma last week. She had a couple of tummy upsets in the month before she died and we took her to the vet of course. He ran tons of lab work and even took an x-ray and nothing showed up. She had a seizure late that night and died early in the morning. There was nothing to indicate she had a terminal illness. Nothing. The vet was as shocked as we were and did a free autopsy. It was a hopeless case and there was nothing that anyone could have done to help her. I only wish we could have had the chance to spare her that last day. Horrible as you feel right now, you were at least able to give your dog that mercy.
Thanks for your kind words and explanations. Jaybay, I'm so sorry for you too. I am taking this so hard. I have been hospitalized twice. Once for falling and another time because I wasn't talking right. I was given numerous tests and they think I may have had a slight stroke, but didn't find anything. This is all stress related. When I lost another fur baby 3 years ago, I ended up with my heart slowing down and a pacemaker. I just take this physically hard. I have another who is 12 years old and I am worried about her. I'm going to work to try and get over this. I miss kissing her little cheeks. She liked that.
Chicky, take care of yourself.