Putting our dog down. When is it time?

Our poodle did have a stroke at age 14, however. At least, that's what our vet said it was. Benjie was in the yard one day and I heard this alarming, almost coyote howl with a gurgling sound and some other hard to describe special effects thrown in. This was on the weekend and at that time, there were no emergency vets in our area. I went to pick Benjie up and he was acting disoriented and moved in a wobbly kind of way. I brought him in and he started drinking water and didn't stop. His belly swelled up like a water balloon. He had temporarily lost the gauge that told him when he'd had enough to drink. There was no WWW to check symptoms and we had no idea what to do. As soon as the vet's office opened Monday AM, I took him in and the vet said from my description it had been a stroke. Not a heat stroke, as the weather was not hot at the time. I assume a stroke can come from a small blood vessel breaking in the brain, unrelated to cholesterol, but don't know for sure. I don't remember the vet giving him any medicine, but the amazing thing is, Benjie lived for two more years without any repeat episodes and without impairments, other than arthritis and the other old dog stuff.