I'm SOOOO happy to hear that Cassie has gained some weight and is doing well!!!!!! How amazing it that!! It's a testament on how she fought to be with you. As far as your colonoscopy - so wonderful that you won't have to leave her alone and that the vet, who knows Cassie, is willing to keep a keen eye on her. For your preparation of your procedure, I sure hope that you can keep close to a washroom.
Seriously, you need to be
very close.
When I had my procedure, I couldn't feel a thing and everything turned out well. All the very best!!!!!