Our pets start out as children. They end up our elders. Then we have to watch them die.
There are differences from our biological children, of course. Some of our pets will never grow to be smarter than a fifth grader. The rest don't think we need to know that they know what we want them to do. Our pets will never go to college or move out of the house.
I don't think it's a matter of being dependent on us as much as they choose to stay with us. They become companions and friends. They love us no matter what is happening or what we do, which is no small feat for some of us. And they encourage us to do better.
What we value most about our pets is not agreement but their acceptance of us as we are.
They demand nothing of us, other than food, daily walks, and rubbing their heads now and then. And if we're sick, they keep us company.
When they're sick, they don't want to bother us, but we sense they are ailing and try to help without knowing the extent of the problem. As they grow older, gray hairs appear. We see the fading look in their eyes, the cataracts, their struggle to move around, and their difficulty in jumping up in our laps.
Our pets are always around, until they aren't.
Knowing they will die before us does not make their deaths any easier to accept. They become family, and we grieve their loss just as much. Do we grieve them less because they were not human? If anything, we grieve them more.
My wife and I adopted two kittens born on our back porch 17 years ago -- Buff and Minya. Together we cared for them until Evelyn died three years later. In the months after, whenever I would stare out the window for hours without moving, or be on the couch crying, Buff would come over, look in my eyes, and cuddle down next to me.
We had long conversations about loneliness and anger, the weariness of grief and philosophy -- all the "why" questions that death brings up but never answers. He helped me work my way back to caring about living. We were a family of four. When Buff and Minya die, the family that knew Evelyn will end.
Eight years ago Buff developed diabetes and I put him on insulin. Last fall, I noticed he was struggling. The vet discovered cancer on his liver and a blockage in his urinary tract, and I had to put him to sleep.
I watched him grow from a shy, playful kitten to a teenager to a 16-pound adult and then become an old man. He was a beloved friend and companion who was always home. Even when he was arthritic and found it hard to move, he would still hobble over to rub against my leg and purr.
Death has torn another hole in my life, and I grieve the loss of a beautiful, noble, and compassionate creature.
Love is not a matter of IQ, but a matter of heart. Our pets show more compassion than some humans we know. I believe that pets share a common consciousness. We simply articulate that awareness differently.
When any relationship of the deep heart ends, we grieve. And terribly.
This post is part of Common Grief, a Healthy Living editorial initiative. Grief is an inevitable part of life, but that doesn't make navigating it any easier. The deep sorrow that accompanies the death of a loved one, the end of a marriage or even moving far away from home, is real. But while grief is universal, we all grieve differently. So we started Common Grief to help learn from each other. Let's talk about living with loss. If you have a story you'd like to share, email us at strongertogether@huffingtonpost.com.