I'm so sorry that happened. Seeing your pet have a seizure is such a terrible thing. The good thing is that they don't know what happened when they wake up, they just realize they are out of sorts and want to be close to you till they feel better. My Springer Spaniel had seizures for many years late in life and we never knew what caused them for sure. Vets won't usually put them on medication unless they know it's going to be an ongoing thing. It's unbelievable that they didn't want to at least run some tests though! I hope it was a one time thing, and she doesn't have to go through it again.