Hi there, this is Dr. Elaine
I'm so sorry for your loss. 7 years old sure is unfair.Melanoma
is also extremely unfair and unforgiving. It can be one of the most aggressive cancers seen in both veterinary and human medicine.
I am going to say something that I want you to take from this if nothing else: STOP second guessing yourselves.
I am certain you made the right decision based on many factors: the information you were given, the potential aggressiveness of this neoplasm, the pros and cons of proceeding with surgery vs not.
It is VERY possible that there was more than aspiration pneumonia going on that was not visible within his lungs--i.e. metastasis (spread of the cancer). Metastatic spread in the lungs can often not be detected by xray if it is not large or disseminated enough to be seen. It is often said a lesion in the lung must be the size of a nickel to show up on an xray--that is big. While MRI might detect it, that is a very costly study, and not readily available in most veterinary hospitals.
Melanoma is one of those cancers that almost requires aggressive surgical intervention to have any hope of arresting it even to any significant degree. My own mother had a small (pea sized) melanoma removed years ago that was actually 10-15 times bigger than that size under the skin (not visible until surgery).
Even if he had "another 3-6 months" without surgery (and this is NEVER something we can actually project--we only have past experiences to guide us and staging the apparent severity of a cancer in order to prognosticate with any degree of accuracy. Even then we certainly fall short.
It sounds to me as if you did exactly what I would have done. We can look at the other side of the coin and say "what if we had NOT done surgery and he died shortly after diagnosis anyway?" Therein lies our dilemma--all the "what ifs."
Please hold tight to the assurance that you did all you could (and probably more) and went extra lengths that many cannot or would not. Bless you and take care. Your memories will turn from tears into smiles, I promise you.
Let me know if there might be anything else.