I wish I could be certain. Winter is almost 16. She has diagnosed Hyperthyroid and has lost a lot of weight over the last year. She was on a topical that I would rub into her ears, and everything was okay. She would purr and I would give treats after. But she kept dropping weight. Took her to the vet and the topical isn't working. We make the decision to switch to an Iodine free diet to battle the thyroid issues and it seems to be okay. She eats the foot, puts a little weight back on. Then she starts limping, back bent, having trouble with the litter box. Over the last week or so she's been vomiting after each trip to the litter box, and barely pooping. Some research shows Constipation is common with Hyperthyroid. And this particular diet makes it worse. At this point she seems to have stopped eating entirely, thought I've seen her drink water. Morning cleans of the litter box are distressingly light. I switch back to regular food, make sure there's three different bowls of water throughout the apartment. Still not eating. Not getting up to poop, though she gets up to pee. Lethargic, no energy. Lies under the living room table, almost like she's hiding Am I just cruelly prolonging suffering? Is she in misery and pain? Should I make the decision to let her go? The thought of that hurts me so much I feel like I'm dying. I've been in and out of sobbing fits for days just trying to figure out what to do. I don't want to lose her...but I'm afraid I'm keeping her alive now for me, not for her. I wish I could know for sure.