I cried the entire week leading up to the appointment for my late 17 year old cat. He was in late stage dementia and kidney failure and had been loosing his eyesight. Pregrieving before really does help you handle yourself for after the appointment. What I did that helped was I bought 5 new bags of

treats so he got to experience his absolute favorite thing, me opening a brand new bag of his favorite treats. He had a dementia rally, terminal lucidity, for a few hours the night before the appointment.