I’ve had experience with medical assistance in dying, with my dogs. Scoff if you like, but I’m sure the rituals and emotional experience of it is very similar. And the worst of it is, the trusting quadrupedal family member has no idea what is coming. For our pets, and severely injured and ill animals of any description, we have almost no reservations about euthanasia for them.
With bipedal family members the experience must be different. Sentience in the human makes the difference, and so we defer to the one who will die to make the decision? But what if they can’t? Or leave it too late?