The choice of phenobarbitol maintainance is a tough and personal one. About 4 years ago, my vet and I discussed it to treat Maureen. We decided that the costs were greater than the benefits for the following reasons. Phenobarbitol can cause progressive liver damage, although due to lack of a gigantic chin study these effects are not entirely known. Depending on how the medicine is adminstered, the chin will have to be caged alone (We were going to put it in her water). Maureen did not exhibit symptoms often (less than once every six months) and only has had two prolonger seizure episodes which required emergency medical treatment in her entire life. Since the emergeny treatment is phenobarbitol or a similar drug, we decided to treat her only in the event of a prolonged episode.
But the upside is that phenobarbitol should prevent most future seizure episodes. I have heard of people using it as maintainance therapy for dogs for years.
Since her blood work is fine, she probably had idiopathic epilepsy (epilepsy with no apparent cause). Unfortunately, this is the hardest to understand and treat, because know one knows why it happens. It may be heritable. The other problem is I have only known of a couple of chins to have been diagnosed with it.
If you'd like to compare notes or talk, email me for my phone number. Also, (even though I should know this already) is Noel a black velvet, white, or mosaic? Where did you get her? It is possible that she is related to Maureen. Maureen's breeder went out of business before her diagnoses, and therefore never knew to stop breeding her parents. Since it is so rare, it is probable that none of Noels siblings have ever shown symptoms. Also, it may not be hereditary in her case at all (epilepsy can also result from head trauma).
Good luck and feel free to contact me.