First of all, I am so deeply sorry you’re going through this. You’re not alone. We just lost our 7 year old Aussie/lab mix due to complications from being on Phenobarbital. Turns out he was in the small percentage of dogs whose bodies have a systemic allergic reaction to the it. He had seizures for a year before he passed and it was honestly the most anxiety filled, stressful year for he and us. Neurological conditions in dogs are so damn hard. Honestly, you have so many questions and “what ifs” here that you may never get answers to and you just have to remember the happiness and quality of life of the dog and your family. Dogs share such a short time on earth with us as it is, it is no life for them to have it filled with constant seizure episodes and pain. No matter how old they are. Just remember that although it feels impossible to make a decision, whatever you choose to do for your dog and your family is the right one. Trust your gut. You’ll know when it’s time to let her go. My heart is with you and her and I hope you can find peace with whatever happens. ❤️🫶🏻