Teeth bared, snarling, our new puppy lunged for my face. I was trying to keep her from nipping my kid when she set her sights on me instead. BAM! My right eye bounced, flashing white, like it was whapped by a baseball. My upper lip stung. My hands flew up to my face.

Though I didn’t see it, my son jumped in. He grabbed the snarling puppy’s harness and rushed her into her crate. “You hurt my mom,” he yelled.

I opened my eyes. “I can still see,” I thought. “That’s good.”

Then I wiped blood from my lip.

“Mom, are you OK?” My son sounded scared. He saw the blood dripping from my lip and smeared on my hand; he got me a towel from the kitchen. His 10th birthday present just attacked his mom after first trying to attack him. Could this get any worse?

Our son is an only child. A gentle, generous, kind-hearted soul, Will’s longed for a puppy for months; before that, he had lobbied hard for a baby brother. With older parents, though, all he got was the lesson that lightning doesn’t strike twice.

Will’s been raised with stories of Zoey the Wonderdog, the lab mix we adopted from the local shelter shortly after we bought our first house. Zoey lived with his dad and me for many years, sort of like a practice baby before I gave birth to our real one.

That dog understood that Will was a defenseless baby. When friends and family came over after Will’s birth, Zoey would supervise visitation. She’d sit quietly near whoever had the baby, and keep an eye on things. “Enjoy that cute little guy, but remember: I’ve got his back,” she seemed to say. “Don’t even think about messing with him.”

When Will woke from a nap or cried, Zoey would sound the alert. It was as if the baby would explode if he fussed too long, and it was her sworn duty to make sure that didn’t happen. Will was learning to stand upright when Zoey became sick, but she’d happily let him hold onto her tail to practice walking. She never complained, never got cranky with the kid, though no one would’ve blamed her if she had.

That’s the kind of dog Zoey was, and that’s kind of the dog we were hoping to find once again.

Instead, we found Sophie.

In the search for a dog, I found an adorable litter of border collie/lab mix puppies online. They were going to be shown by a rescue group at a local pet store on the Fourth of July. The puppies had Bavarian-sounding names like Marta and Gretel, and they looked fluffy and sweet.

Figuring no one would be adopting a puppy on the Fourth of July, we got to the store about 15 minutes early. The size of the crowd spilling out into the parking lot told me I was wrong.

Like me, everyone was there for one of the “Sound of Music” puppies, as the rescue group worker called them. They were adorable. The competition for them was stacking up to be intense, and we got there way too late.

“Let’s see what other puppies are here,” I suggested.

That’s when we found Sophie. The information sheet said she was a lab mix who was “very bright,” and “doing well with housebreaking.”

So far, so good. Sophie was alert, peppy and cute. I held her, and as she wriggled, I looked at my son, who signaled his approval with a nod and a shrug. No one else applied to adopt her, so she was ours.

Thus began our short and chaotic journey with the puppy from hell.

You need to know that I’m no stranger to dogs; I’ve lived with six of them throughout my life. They’ve all had their own personalities and quirks, but not a one was mean.

After the first couple days with our new puppy, I became concerned. Sophie didn’t much like to play, which I found odd, especially for a healthy puppy. She didn’t like to go for walks, either. She snarled a lot, and her favorite pastime was going after my kid. Her fascination with biting also seemed way beyond the norm for puppy teething.

As we struggled with the new puppy’s behavior, I kept reminding myself to be fair to her, to not compare her to our old dog. It was time for Will to get a dog, and Sophie was the puppy we chose. But there were problems.

“Sophie’s pulling his pants down,” my husband yelled from the yard one afternoon. I dropped what I was doing and went to the door, expecting to see some funny dog-foolery going on.

Instead, Will stood in the middle of the yard, looking panicked as he desperately held his pants up with both hands. The little puppy swung between his legs, her teeth sunk into his shorts. My husband got the dog to let go and she retreated to the back of the yard.

“That’s pit bull behavior,” a friend said when I related the story.

The rescue group, which got Sophie from a kill shelter, couldn’t vouch for her lineage other than to say they thought she was a lab mix. The veterinarian thought Sophie could be part beagle.

I searched the Internet for photos of pit bull puppies; some resembled Sophie, some didn’t. And there’s nothing that says being a pit bull, or even part pit bull, accounts for aggression.

“I think there’s something odd about the puppy,” I said to my husband one night. My husband, the person in the family the puppy actually seemed to like, agreed.

“We can give her back, but what does that teach Will,” I said. “That when the going gets tough you just abandon things?”

We decided to seek help. First we called the rescue group with our concerns about Sophie’s behavior. The group put us in touch with the woman who fostered Sophie before we adopted her.

“She’s got it in for my son,” I explained. “She keeps going after him.”

“We never had any trouble with her at all,” the dog’s foster mom said. “My 7-year-old daughter used to carry her around like she was a doll.”

Then we got the advice that was given to us over and over again as we looked for help: Everyone, from the animal rescue folks to the veterinarian to the cashier at the pet supply store, recommended obedience classes for my son and the puppy. “He’ll learn to take charge,” they said. “It will be a good thing.”

It was as if the fault for the puppy’s aggressive behavior rested squarely on the shoulders of my son, who they all figured didn’t know how to be in charge.

We decided to work it out, to work with Will and to try even harder with the puppy, thinking we chose a dog that was simply a bit wilder than the others we’ve known. We thought we could fix things. Outside of nips and scratches and some torn clothes, the dog hadn’t done any really big damage, and she was so darn cute.

We enrolled in a puppy obedience class, and I talked to my son.

“I think Sophie might think you’re her puppy, that she can boss you around,” I said. “Does that make sense?”

My son nodded and shrugged.

“You’ve got to show her who is boss,” I said. “You’ve got to take charge. We’ll go to puppy class and we’ll work it all out.”

Then, just days before we were to start class, Sophie went for my face.

A minute earlier, I was sitting on the sofa with my laptop, trying to write. Will was sprawled out next to me, watching a cartoon. Sophie was busy with a rawhide chew stick.

Something about my kid drew the puppy’s attention, and she raced over to bite his legs.

That’s when I tried some advice I found on the Internet late one night as I desperately searched for a solution: Push the puppy away, saying “No” firmly.

I did it once.

The puppy was unfazed. Snarling angrily, she came back for my kid’s legs.

I pushed her away again as my son leapt onto the back of the couch. The puppy tried to claw her way up.

Figuring that I hadn’t said “No” firmly enough, I leaned over to get a better handle on the puppy to move her away.

That’s when she set her sights on my face. All I remember is her snarling mouth and bared teeth coming at me.

When it was over, I made a frantic phone call to the rescue group people, who responded quickly and professionally and took the puppy away. Then, I caught my breath and looked in a mirror. Bruises were already forming on my eyelid and eyebrow; my lip was cut in two places.

Despite my frightening but definitely not-life-threatening injuries, I felt lucky. This could’ve turned out a whole lot worse, but it didn’t because, in the end, everyone was wrong: my 10-year-old kid took charge of the puppy just fine, precisely when it counted most.

The problem was the puppy.

These photos were taken five days after the puppy came after me.