The dog we did not keep

Four days. That is how long the dog was with us, and it has been twenty years, and my sister still brings it up in the tone that means: I have not forgotten what you were in that week.

He came from a friend of my mother's, a small brown thing, no particular breed, about four months old, with an ear that did not stand up. Somebody had left a litter at a bus stand. He arrived in a cardboard box and within an hour he had found the thing that dogs find in a house, which is the spot with the best light and the most foot traffic, and he lay there and did not move.

My mother had said yes to four days. That was the arrangement, and it feels important to state it, because what happened next has been remembered in my family as an act of betrayal rather than an agreement.

By day three we were, all four of us, entirely reorganised around him. My father, who had said the sentence you would expect, was feeding him from his own plate. My sister had named him. I had worked out the feeding schedule on a sheet of paper. This is the bit of the story people leave out when they tell it as a warning about my character: we were all in it.

On day four my mother said, so. And I said the thing that I have had to live with, which was that we should think about the next ten years. Who walks him in July when we are at my grandparents'? What does the plan look like when he is ill and the vet is across town and my father's shift is at seven? What happens to the furniture, the exams, the summer, the money?

I want to be clear that every one of those was a real question. That is why the memory has stuck: I was not being cruel, I was being the person who does the arithmetic, and the arithmetic was roughly correct.

What I did not count is that a family is not a system of optimal decisions, it is a system for absorbing costs together. My father had already decided to do the July walking, it turned out later. My sister had worked out that the vet near the market did house visits. They had each done their own arithmetic, and their arithmetic included each other, and mine had been done alone in a room and then announced in a tone that sounded like the end of the discussion.

We found him a home with a family two lanes over, and I have since seen him around for years — he was called something else by then — and he lived to a good age. So this is not a tragedy. It is a much smaller and more common thing: a person who mistakes the role of being the careful one for the role of being the one who decides.

I am the careful one in my own household now. I catch the impulse when it comes: to do the sums privately and then present them as facts. Sometimes it is my job. Sometimes it is just me, closing a door that other people were walking through, and the tell is always the same. When I am doing the arithmetic because everyone is included, it feels light. When I am doing it alone, it feels important, and important should never be a private feeling in a family.