Is my dog having a heart attack,or stroke?
If this has happened more than once, I would see if anything correlates with them. She may be having minor seizures. I believe if it were a stroke the side-effects would be longer-lasting, and a heart attack at that age doesn’t fit what you are explaining. I believe if it is seizures, which can develop at any time in a dogs life and may leave no residual effects, it may be worth your while to see if you can read when the dog is about to have one or have a good idea what is setting them off (after activity, at high stress-times, etc.). If so, there are some medications that may lesson their effects.
I had a dog that had a similar problem. He was very old and since I didn’t know what it was at the time, I ended up having him put down. Recently, however, I saw a program on Animal Planet about vet interns. One of the cases they had was a dog that couldn’t stand up and was basically paralyzed…symptoms very similar to what you describe. They determined it was something called Coonhound Paralysis. It happens as a result of ingesting raccoon urine, possibly after having sniffed it on the ground or something. Apparently it can cause nerve damage and the symptoms you describe, but the dog can survive with vet care.