cancer
hey i am very sorry to hear about your dog i am going thru a similar situation right now. an adult female i have had a swollen foot which was believed to be an infection after some antibiotics the swelling went down and she seemed fine her foot started to swell again so i went back to the vet took x-rays and no one could figure out what was happening i went to several specialist and after many x rays and minor procedures we had to do a biopsy of the bone for samples to test well last friday the results came back saying she had advanced cancer and that i should bring her in monday as euthanisation was the only option. after speaking to a friend who had a dog w/ the same cancer she told me that it would be a matter of days due to the operation igniting the cancer and to keep an eye on her and that she would give me a look to tell me she has had enough when it was her time(along with other signs of course). being the weirdo that i am i explained this to her (yes the dog) as we went to sleep that night she sleeps in a bed beside mine (she wasn't moving around to well) i told her you just give me the sign..... the next morining i woke up to her licking my face and wagging her whole body (this was definatley not the sign) every day since then knock on wood she has gotten a little better she is happy and the swelling in her foot has even gone down a bit for the 1st time in weeks. I think cancer in dogs is somewhat similar to that in humans in which it isn't always predictable i myself am just researching it now but this is one thing i have noticed from case to case. there is a ton of info on the net, the one thing that i have heard several times is that dogs can actually smell cancer i have noticed here that some of my dogs that would usually be upset by her being in the house gettin most of the attention aren't, and females that are normally agressive towards her and that have been in the past are not now. i think the reason for your vets concern with the breathing is cause cancer will usually travel to the lungs quickly but this is also a very common effect from infection bacterial and fungal so it is definatly not a sure tell sign. also the excitement from the operation, meds, and stress can cause irregularities in breathing as well. i wish you all the best with your dog and i will keep my fingers crossed for her results. if you have any questions feel free to message me i will try to answer as best i can.
good luck
Evan