I'd add that prospects for recovery and quality of life are important factors. We had a beagle pup that developed severe seizure issues, and we spent a couple thousands trying to figure it out. Our final option was to do some testing through Iowa State for $1500 more (or so, can't remember exactly), but that would have only helped diagnose the cause (maybe). Before we got to that point, she went into a seizure that she wouldn't come out of (could only prevent them with heavy sedation, and as soon as she came out, she went back into seizure), so the decision was made for us. Just a heart wrenching situation with her.