Hi, I am late to the post but I did want to comment on both meds and canine seizures. I had a standard poodle and like you the first time he had a seizure, I was terrified and was also certain he was having a heart attack. However, he was diagnosed as classic idiopathic canine epilepsy and like the classic cases, my dogs epilepsy also began when he was 2 years old.
I tried phenobarb but the effect on my dog was disastrous. He was a shell of his prior smart, funny, energetic self.