Dogs are not our whole lives but they make our lives whole. Roger Caras

I’m not sure when Buster, our border collie mix, became an old man. The changes crept in so slowly that I didn’t even notice until Dan pointed out the clouds gathering in his gentle brown eyes. Only then did I see the way his bright white goatee has turned into a full beard.

Dog years are fluid, the calculation of age in human years more complicated than just multiplying by seven. Fifteen years for the first year of a medium-sized dog. Nine years for the second and five years for each one after that. Buster will be eleven this fall, which, based on his breed, makes him 69 in dog years, according to the American Veterinary Medical Association. Although he hasn’t regained his full mobility after bursting a disc in his spine two years ago, he shows no sign of being the “senior” dog he’s considered to be. Despite his lack of traction on our tile floors, he can scoot around with the same speed he’s always had, routinely beating me to the front door after he hears the bell ring. At night, when we take him out for a final bathroom break, he will weave rapidly from one side of the lawn to the other, pausing only to listen for our resident skunk or the deer who hang out in our yard. He can walk four miles in his wheelchair, and when he launches after a squirrel that crosses his path, I can barely rein him back in.

We got Buster four months after Bronco, our sweet-tempered, mellow yellow lab died in his sleep. With Jimmy away at school, and Dan and Molly gone all day, the house felt way too quiet and lonely.

From the beginning, Buster has been my dog. Smart as a whip and utterly neurotic, he attached himself to my side like Velcro and has not let go. Before his injury, he followed me everywhere in the house, content to lay near my feet as I worked in my home office. Despite his border collie energy, he spent long hours half laying on my lap in the room where Jimmy lay dying, sensing in the way dogs do that I needed both his presence and solid weight of him. He walked for hours on the horse trails with me after Jimmy’s death, keeping steady pressure on the leash as if to keep me anchored to the world. Content just to be together, he was impossible to tire out.

Comedian Louis C.K. observed that bringing home a puppy is a countdown to sorrow. Buster has already dodged death twice – once when he ate a wad of terry cloth towel that lodged in his intestine, completely blocking it and again when he became paralyzed after his disc burst. After the neurosurgeon repaired his spine, we spent a stressful four or five days hoping he wouldn’t develop Myelomalacia, a rapid and progressive necrosis of the spinal cord that becomes fatal once it reaches the nerves to the diaphragm which control breathing.

We carefully considered both surgeries but decided each time we had to do what we could to try to save him. Buster was only four when he got the blockage and eight when the disc burst. The idea of putting him down was unimaginable, even though the odds were only 50-50 he’d ever walk again after spinal surgery. I had watched Jimmy’s life become more and more constricted as the cancer took over his body, first making it harder to walk, then impossible. Yet Jimmy never stopped being fully engaged with who and what he loved most. He taught me that a diminished life is still worth living.

So here we are with Buster who alternates between getting into trouble as he scoots around the house and acting as if he’s helpless and needs me to do everything for him. His physical constraints have strained the household at times. Yet he’s in good health and shows no sign of being uncomfortable or in pain. He still finds so much joy just being with his people, always up for a walk or snuggle. His ears have caught so many of my tears, and his warm, solid presence is still the best comfort when I’m longing for Jimmy. We don’t know how much longer we’ll have him, but despite all the challenges, I will miss my sweet dark shadow when he departs. Not just because of how fiercely he loves me, but also because of the way he has continued rolling forward, no matter how daunting the obstacles in his path.