My little cat Theodora – Theo for short – was put to sleep on Sunday.

Anyone who has ever had to say goodbye to a beloved pet knows how I am feeling right now. Pretty low. A wise friend, knowing that Theo’s days were numbered, told me last week, “We don’t own pets. They own us, and they own our hearts.” That has brought me comfort in the last few days, as Charlie and I adjust to life without Theo.

Theo has been part of our lives since the day in May 1998 we found her behind a cyclone fence at an abandoned electric station a few blocks from our home. She was so small we thought she was a kitten. She was cold, dirty, and hungry. Miraculously, she was also purring, riding high on my shoulder as I carried her home. She was coal black, with yellow eyes. She had no tail, just a little stub at the end of her rump.

With two cats at home, we weren’t looking for another cat. But that’s how it goes. We weren’t sure how Elfie and Isabelle would react. Elfie took to Theo right away; Belle simply ignored her.

We took the little black cat to our vet the next day for a checkup. He estimated she was about eight months old and thought she might be a Manx, as she had other characteristics of the breed besides the lack of a tail.

In keeping with our custom of naming our cats after royalty, we named this one Theodora after Empress Theodora, wife of Justinian, who ruled the Byzantine Empire from 527 to 565 AD. (One learns a bit of history being married to a history professor.)

Like her namesake, Theodora was imperious. She regularly demanded – and received — attention. She loved keeping company with Charlie in the study, curled up in the upholstered chair a few feet from his computer. She loved hanging out with me in my sewing room, often usurping my chair when I got up to use the iron:

One of my favorite photos of Theo is this one, peering at me through my sewing machine, willing me to stop sewing and pay attention to her:

In her later years, she liked to crawl under the covers at night and snuggle with us, and she would purr for the longest time before finally drifting off to sleep. The last couple of years she launched a nightly yowling campaign to coax us to bed, usually way before bedtime.

Theo’s coat remained a glossy black as she got older, although late in her life there were a few white hairs among all the black ones. And there was that one white whisker. One time it fell out, and the new whisker that grew in was also white:

As the years passed, we continued to refer to Theo as “the kitten” because she was so petite. At her peak she weighed 7½ pounds. At the end she was a little over 4 pounds. Despite a voracious appetite, she had been steadily losing weight over the last couple of years. She was being treated for thyroid disease and incipient kidney failure. By now she was also completely deaf.

A few weeks ago problems associated with kidney disease began to surface. We could tell she was in some distress. After multiple trips to the vet, we had to face the fact that, while we might try different treatments that would prolong Theo’s life, she was never going to get better. We didn’t want to wait until she was suffering greatly to make the decision about euthanasia.

My twin sister Diane (whose cat Alex lived to be 23) told me the other day, “In my next life I want to come back as a cat and live at the Portland White House.” I know Theo had a good life, and I am glad Charlie and I were able to provide that for her. But it doesn’t lessen the profound sadness we feel at her absence.

Even now, I expect to see her demanding to be fed or given treats every time I walk into the kitchen. I catch myself looking for her in her favored napping spots: the chair in the study, the top of the clothes dryer, the rug on the heated bathroom floor, the mantel in the living room when the sun was just right, and yes, the chair in my sewing room.

When I was in Paris a year ago at this time, I bought a souvenir mug that featured a chat noir (black cat en francais), partly because the cat reminded me of Theo (minus the tail). Theo wasn’t terribly photogenic. Even though she was a happy cat, in photos she always looked like she was scowling. Take a look at the cat on the mug. Doesn’t it look a lot like Theodora?

She was with us for exactly 18 years. RIP, kitten.