Sleeper sofas sprint across a gravel road faster than Walker wheels from family room to food bowl. We started calling her Limper.

Something had to be done.

“She has a torn anterior cruciate ligament,” the vet said.

Until then, I didn't know dogs had knees. I don't see a knee. Show me the kneecap. Let's see a squat thrust. “She has three others,” I said. All working. That's one more than the rest of us.

(A few years back, another vet diagnosed Walker as manic-depressive and suggested we put her on dog Prozac. I got some for myself instead.)

The vet said if we didn't fix the knee, her hip would go, then another hip and another knee and pretty soon she'd need a wheelchair to chase the Wiffle ball.

She's a 7-year-old black Lab, loved completely by Jillian the sixth-grader. Were it not for Jillian, Limper would have been shown the gate the first time she busted out a window screen to get at the lawn care guy. Twenty screens later, Limper is still hanging around, lamely.

It's funny what we do for our pets. Why do we talk to them? What's with the rhetorical questions? Are you a good girl? Hell, yes, I'm a good girl. Now get off your rump and pour me some dinner.

A few years ago, our guinea pig contracted a head cold and expired while wheezing. People told us we should have taken Jake to the vet. But here's the thing: Jake cost 15 bucks, brand new. The vet charged $20 just for the office visit.

Jake, bless him, was totaled.

And yet . . .

“A person came in with a gerbil,” said Keith Murrell, DVM, the veterinarian charged with turning Limper back into Walker. The family cat had snagged the family gerbil and triumphantly broken the little creature's leg. The family wanted the leg fixed.

“I didn't quite know what to do,” said Dr. Murrell. It's not like they make casts for gerbils. Or little gerbil crutches.

Dr. Murrell amputated the leg. “I didn't know what to charge them,” he said. “I mean, it's a two-dollar animal. I think we charged them $70 or $80.” The gerbil lived happily for another year. Had a heckuva time on the hamster wheel, though.

Dr. Murrell has removed mammary tumors from pet rats, treated feline lymphoma and taught pet owners how to give their four-legged loved ones injections for kidney problems. He has had dog owners pay to replace their pets' hips, at $1,500 a hip. He has had owners give their diabetic dogs insulin injections, twice a day for years.

He knew a high school student who worked part-time just to pay the $400 a month needed to treat her golden retriever, diagnosed at four months with epilepsy. “They continued until the dog was four or five,” Dr. Murrell said, “when they thought it was best to let go.”

Ultimately, they are not just animals. They are family members, with one critical difference: Pets always reveal the best of our natures. Limper still harasses the window screens. Socially, she's just this side of Hannibal Lecter. She also allows Jillian to use her side for a pillow.

When I came home late Thursday night, she three-legged her way down the stairs to offer greetings. It was good to see her tail still worked. With dogs, the tail's the last to go.

The day we put down our last dog, her legs quit and she fell down the stairs. We scooped her up and took her to the vet. We knew what we had to do. Her eyes said she knew it, too.

Sooner than anyone knows, Walker will face the same fate. It's a measure of our love for our pets that we keep falling madly for them again and again, when the end is always the same.

Walker came home from surgery Wednesday, her bum knee fixed and bandaged. Jillian's face lit up the neighborhood. It's why I spent $750 to fix a knee I didn't know a dog had.

E-mail pdaugherty@enquirer.com.

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