Our Shepherd just had 7 attacks on New Years Day. They were all under a minute or so. She's had a couple in the past year, but I tell you, we were really scared. At that time the vet told us to monitor her and let him know if the condition worsened. It sure did. Got her on phenobarbital now, and that seems to help. Her muscles are still sore, poor thing. Can you give any advice?
Pheno is the norm, there is another medicine that has to be mixed, and can be kind of dangerous. Make sure to be constant on the Pheno, and not miss any days. There really isn't much you can do, some dogs have seizures once and never again, its a crapshoot.
My Airedale had cluster attacks of about 20 or so siezures over a 3 day period every 6 months or so. What may have killed him is that we used a different type of medicine on him during his last siezure, in any event, he died a few hours later.
Epilepsy in dogs is a terrible thing to have to watch or treat. My greatest worry was him having them and falling into the pool. Best of luck. The Shepard is vulunerable because there was some real bad breeding in the last 20 years as the dog became real popular, ruined lots of dogs.