re: Reading dog threads on here for years.... when do you know it's time for the big sleep?

My mastiff outlived his expentancy, but I had to put him down recently. He was slow to get up but ate regularly and was active when needed to be. He seemed to be doing good, but I could tell it probably wasn't going to be much longer. Less than a month ago before I left for work he had a seizure, never had one before. He came out of it ok, so I had the wife watch him and I went to work. She called and told me he had another so I headed back to get him and bring him to the vet. Within two hours he had 9 seizures and they found a mass on his lungs. At that point I didn't have a choice. Sometimes you'll know and sometimes it'll come at you with no warning.