If you are reading this before the loss, while it is still a decision in front of you and not behind you, then you are carrying one of the heaviest things a person who loves an animal is ever asked to carry. We want to say that plainly before anything else.
The medical part of this question belongs to your vet, and we would point you firmly to them. They can tell you what your animal’s body is actually doing, what pain is and isn’t being managed, what the realistic days ahead look like. Many vets will walk through a quality-of-life assessment with you — appetite, mobility, whether the good days still outnumber the bad. Ask them directly. They have stood where you are standing many times, and they will not think less of you for any version of the question.
But the part that no checklist answers is the part you actually came here with: how do you choose. And the honest answer is that it rarely arrives as certainty. Most people describe it as a quiet, terrible knowing that shows up before they are ready to admit it — a sense that they are keeping their animal here, now, partly for themselves. Wanting more time and not wanting them to suffer are both love, pulling in opposite directions, and being torn between them is not weakness. It is the position the love puts you in.
Whatever you decide, deciding it is itself an act of care — maybe the last and largest one you get to do for them. That is exactly why it weighs what it weighs. You do not have to carry the weighing alone, even if you have to make the call alone.