In fact, Callie was the fastest dog I had ever seen.

The first time we let her in the backyard, she established a perimeter by running circuits just inside the fence. Most of the yard, though, was thick with English ivy, which in the lush southern climate grew in knee-high thickets. Callie would run full tilt, alternately leaping over the ivy and then diving beneath its heavy leaves. As soon as she got to the fence line she would tunnel under the ivy, tracking the edge of the fence. Like a torpedo, all you could see was a bulge moving through the ivy at high speed, only to explode out in a leap of joy. With her back muscles flexing and unflexing, she ran like a cheetah.

On top of her speed, Callie exhibited a laserlike focus on squirrels. Once caught in her field of view, a squirrel would be chased up a tree in sheer terror with Callie scrabbling at the bark. The treeing of squirrels wasn’t the main characteristic of terriers, and although in all likelihood Callie was a mongrel, I couldn’t help but hold on to the fantasy that we had found an unrecognized purebred at the shelter.

The treeing of squirrels turned out to be the key to decoding Callie’s heritage. Not being native to Georgia, I was unaware of a breed peculiar to the South: the treeing feist. According to the American Treeing Feist Association, the treeing feist, or mountain feist, existed in the southern Appalachians long before rat terriers were brought to America. While terriers were bred to catch vermin, feists were bred to hunt. And while squirrels are their primary prey, the feist will gladly hunt raccoons, rabbits, or birds. With longer legs than terriers, feists are built for silent speed. They live to tree a squirrel until its owner comes to catch it. The feist has a storied history intertwined with the beginnings of the country. George Washington wrote about them in his diary, and Abraham Lincoln even referred to them in a poem.

Over the next two days, Callie’s personality began to emerge. And even though we had changed her name, somehow the shelter had been closer to the mark. She loved to eat.

Every day when I came home from work, Callie would burst into the room and jump up and down like a pogo stick, wagging her tail furiously, her eyes filled with pure joy. But on the fourth day, when I came home, she just lay on the rug, hardly moving at all.

“What’s wrong with Callie?” I yelled out to Kat, who was busy helping Helen with homework.

“What do you mean?” Kat asked.

“She’s just lying here on the floor.” This brought everyone running into the room.

Maddy covered her mouth as her eyes began to tear up.

“What’s wrong with her?” Helen asked.

Callie just rolled on her side and began to whimper.

I kneeled down to see what was wrong. Her belly was bloated out of all proportion to her rail-thin figure. When I touched her tummy, she squirmed away and made a little whine.

We immediately set to looking for what she might have eaten. I expected to find the tattered remnants of a shoe or one of the kids’ toys. Ten minutes of searching yielded nothing, and Callie just seemed to be getting worse. Moving from sitting to standing to lying down, she was unable to find a position that didn’t cause her pain.

Finally Kat yelled out from the kitchen pantry. “I found it!”

This is where we kept the dog food. Over the years, we had learned that it was cheapest to buy fifty-pound bags. For ease of access, we stored the food in a large plastic bin on the floor of the pantry. With the lid on, the bin had successfully kept the dogs from helping themselves. Until now.

The lid was pried off, and a few bits of kibble were scattered about. Callie had somehow figured out how to open the container and had gorged herself into oblivion. There was still plenty of food left in the bin, but then again, none of us knew how much had been there before she started. The bits on the floor indicated that she had eaten so much that she hadn’t bothered to pick up the remaining scraps.

Helen was on the verge of panic. “We have to take her to the vet!”

I looked at the clock. Past six. Kat was thinking the same thing: after-hours emergency visit. This was going to be expensive.

Callie was such a thin, little dog, and her belly was like a balloon. It was hard to imagine how all that stuff was going to make it through. Maybe she ate so much that she tore her stomach. Was that possible? I had heard of such things happening in humans, but never in dogs.

“Do you know what happened to the rawhides?” Kat asked.

“What rawhides?”

“The pack of rawhides I bought yesterday.”

As Callie writhed on the floor, we both knew the answer.

We headed to the emergency veterinary clinic. This was a fully staffed, multispecialty hospital, manned 24/7 and arrayed with the latest medical technologies. But unlike a human hospital, this was strictly pay in advance. Two hundred dollars to open a tab.

We weren’t exactly sure what else Callie had eaten, so the first order of business was an X-ray.

“You see that?” asked the vet as she pointed to what looked like the silhouette of a dog filled with popcorn. “That’s all food. The good news is that there aren’t any foreign objects.”

“And the bad news?”

“She can’t really drink anything in this state. If she gets dehydrated, the food could turn to concrete in her stomach, which will make it very hard to pass. I recommend we give her an IV to keep her hydrated and keep her overnight.”

None of us wanted to leave our new pet overnight in the hospital. Helen summed it up: “Daddy, she just came from the shelter. She’s really scared.”

“Can’t you just make her vomit?” I asked the vet. That was clearly not where she had intended the conversation to go.

“We can try,” she replied with some resignation. “But it doesn’t usually work at this stage.”

Since there wasn’t much of a risk from trying, Callie received an injection of apomorphine, a potent emetic. Within five minutes she began retching. But, as the vet had predicted, nothing came up. Callie just looked confused and frightened.

There wasn’t any choice. With tears all around, we said good-bye to Little Miss Piggy and trundled out of the hospital. Even though she had been with us only a few days, I couldn’t help but feel that we had somehow failed her. What kind of pet owners were we if our new adoptee landed in the hospital within the first week?

The next morning, the hospital called to say that Callie’s vital signs were stable but that she hadn’t passed anything yet. They recommended keeping her another twenty-four hours.

“Can we take her home?” I asked.

“We don’t recommend it.”

Helen pulled at my sleeve, begging me to pick her up.

Kat and I figured that if anything bad was going to happen, it would have happened already. Besides, Callie had the benefit of being rehydrated by IV, which we hoped would keep her tanked up until the food made its way through.

At the hospital, we had to sign Callie out “against medical advice.” Yes, we were very bad dog owners. When we got home, Callie bounded into the house as if nothing had happened. She drank a bunch of water and ran outside to porpoise through the ivy.

We had medical insurance from the animal shelter through the first thirty days of the adoption, but the insurance company denied the claim. Some fine print about covering only foreign-body ingestions, not pathologic overeating.

It didn’t matter. I was just grateful Callie was okay. And she would soon change my life, helping answer my questions about what Newton had felt and eventually revealing clues to the deeper question: What are dogs really thinking?