Hi Boeriemore -
Sorry to hear that your dog is still having problems with seizures. One of my dogs has epilepsy, so I understand how difficult it can be.
My dog, Keely, has been on a variety of medications for her seizures. The first medication that she was given was phenobarbital. It took some time to get her to the therapeutic level, however, and we had to go to a specialist to get the correct information. The therapeutic levels given by the drug company are not always what a neurologist would recommend. We had to check her blood often to make sure she was maintaining the levels. However, we still did not have any luck with controlling the seizures. The specialist also gave us a rectal valium protocol to administer when she had a seizure in order to stop the clusters from occurring. We give her one dose during the seizure, then another dose 20 minutes later, and then another dose 20 minutes after that. You should check with your vet about the dosages, however.
Next, we added the potassium bromide. It had no noticeable benefits and it made my dog extremely stomach-sick, to the point where she was vomiting almost every day. The vet took her off of it very quickly.
The next thing we tried was adding levetiracetam (Keppra) with the phenobarbital. Like potassium bromide, this one is meant to accompany the pheno for dogs with refractory (difficult to control) seizures. She was on this one for about four months or so. We enjoyed a honeymoon period of two months seizure free in the beginning, then it seemed to make things exponentially worse. She was having seizures pretty much every week after that, which was much more frequently than before she was on the levetiracetam. We decided to abandon this medication as well.
Now Keely is on another drug called zonisamide with the phenobarbital. She's doing extremely well on it and there are little side effects. She hasn't had any seizures in three months, which is the best she has ever done. There is a study about the use of zonisamide in dogs that I read about... it had a fairly small experimental group, but about 58% of the dogs reacted favorably to the medication. And, for those who did, they seen an average 81% reduction in seizures. It gives me the impression that this is an "all or none" type of medication. It has been working for Keely amazingly, so I'm glad of that at least.
Anyways, good luck with trying to determine the next course of action for your dog! Please let me know if you have any questions... I feel like I'm getting very well-versed in canine epilepsy, unfortunately!
"Happiness is a warm puppy."