I have always hated this question, although most clients ask it sooner or later. I have heard it so many times, over the heads of much-loved but declining pets. It's a horrible subject. Horrible and very emotive, but that's not why I have hated it so much. No, the reason I've always hated it, is because I never have the right answer - and that's not because I'm not a good vet. Rather, there is simply never a 'right' time to sign a bit of paper authorising the euthanasia of someone you love.
Should 'You Just Know?'
I have heard people say they 'just know.' And I'm sure that some people do: they wake up one morning and suddenly understand that their companion has quite simply had enough. My Mum used to be a huge advocate of this, but when I thought back, her elderly dogs both suffered sudden declines. For example, one of the pets of my childhood (Bruce) was already badly arthritic when he had a bad fit which left him suddenly blind. As horrible as it was in that case, the decision itself must have been relatively cut-and-dried.
But if that isn't your experience, don't worry; it has never been mine either. My last dog never had neurological deficits; the arthritis just got worse and worse, bit by bit, and there never was a day that was significantly more terrible than the previous one; yet suddenly, he was a shadow of what he had been. In this case, I think it is human not to be sure. But it is also human to think that somehow, you ought to be. This expectation brings feelings of helplessness, mental paralysis and pain.
'When the pain / illness / sickness is too much.'
So how much is 'too much'? What do we measure?
Some say they'll know when their dog no longer gets up to greet them when they get home from the shop. For others, a dog that doesn't try to greet them is fine, as long as she can still enjoy a nice fuss. Perhaps she will rise slowly, and poddle over to her owner when she's ready. After all, there are paraplegic dogs out there who haven't 'got up' on their own in that way for years, but are still demonstratively happy. There are other creatures whose pain relief, if required, is still working, but they might be in different kinds of pain: confused, or permanently dizzy. The pain doesn't have to be physical for it to be 'time.'
To help to quantify how much pain or illness is too much, some vets encourage owners to fill in questionnaires; to objectify the problem using a score.
Some people find it easier to gauge in numbers of a quality-of-life scale; it gives them something palpable to discuss. If gauging things with numbers is your thing, then ask your vet about this. There are several versions available.
'When there are (or are definitely going to be) more bad days than good days.'
Again, two different owners might judge this differently; the definition of 'a good day' is probably different for every owner and dog and will certainly change over time. But I think that's okay: it's right that different pets are different because animal-human bonds are so individual. But then there's the question of what ratio of 'no' days to 'yes' days is okay. Is one good day in two okay? How about one good day in three? Two good days in three? Four in five? How about two fantastic hours a day and then mostly sleeping? Again, what works for one family pet here isn't going to work for another.
But wait - we've talked a lot about the limitations of different ways of deciding. So what do we do?
Next time it's me, I will decide using all of these ways; by measuring pain scores when applicable; by subjectively labelling days 'bad' or 'good' days in a diary, or even recording important incidents, or a rough number of 'good' or 'bad' hours. I will decide by talking to all the people who know the pet well (but be aware - good listeners will often say what they think you want to hear). I will decide by collecting as much medical understanding as I can about what was happening.
Armed with all of this, I'll decide using instinct, and by talking in advance with everybody at home, so that I understand what everyone else believes. I think it's worth having difficult conversations about 'how things are,' 'good and bad days or weeks' and how much 'bad' is okay. For sure, not all family members will agree, but if this is the case, we can agree in advance about how the decision should be made. Whose decision should it be? Do we put it to a vote? Will the children get a say? What will we do about the ashes? Will we have a private cremation? What arrangements can be made?
In my experience, if you talk about it a lot, if you have all these conversations, then.....
.....it will still be really, really tough when the time arrives. You still might not walk away feeling that you got everything right. And that is a very normal feeling because death, like life, isn't perfect. The death of a pet is difficult and actually, that is okay.