My dog, Tucker, had a seizure starting at 4:15 AM. It lasted 21 minutes! He has had a seizure disorder for almost a year but usually they last about 2 minutes. He has been to see two neurologists. The first neurologist said to watch him, no treatment! He is now on three medications and the frequency decreased after adding the third drug. He had an MRI and lots of tests, all normal. The cause is assumed to be a genetic glitch. I know it is unlikely he will ever be seizure free, even with meds, but that long one was just plain scary. Good news, he seems fine now. I talked to the neurologist and adjusted his medication doses. Hopefully, he'll never have another long seizure.