It really hurts when a trained Dutch shepherd sinks its teeth into your flesh. Even when you’re wearing tightly woven burlap. Even when that’s exactly what you’ve volunteered for.

On a hot and wet Virginia day in August 2011, I accepted the invitation of Chris Jakubin, a former Air Force military working dog (MWD) handler, to visit Langley Air Force Base. At the time he was kennel master of the U.S. Air Force Academy, and he was touring a few Air Force bases offering special clinics like this one. It was the perfect opportunity for the book I was then reporting, “War Dogs: Tale of Canine History, Heroism, and Love,” which came out this month. Only after I’d arrived did Jakubin suggest I submit to a canine attack. At first I thought he was joking.

“Catching a bite,” the term of art, is exactly what it sounds like. It’s a little like turning yourself into a human a chew toy. And it’s a crucial part of how a dog trains for patrol work. Bite-work is learned in stages. This is for everyone’s safety—the dog’s, the handler’s, and the decoy’s (the decoy, usually another a handler, plays the role of “perpetrator” so the dog can learn how to detain a fleeing suspect during patrol work). If a decoy catches a dog incorrectly—turns the wrong way or keeps his body too rigid—he can really hurt the dog and himself.

A decoy, naturally, wears a bite sleeve or a full bite suit. These vary in size and bulk, but ultimately their weight is gradually reduced until the decoy is wearing something thin enough to hide under street clothes. This way the dog learns to associate the bite with a perpetrator, rather than with the suit.

The suit was huge. Two women handlers helped me into the gear. They held out their arms so I had something to hang on to and worked the zippers running down the side of the pant legs so that I could climb in. The jacket, heavy and huge, was easier to get on but impossible to wear. Jakubin, who had been watching from nearby, handed me a tack suit jacket instead, which was also big but not as bulky. It didn’t fit exactly but it was close enough.

Under the weight of the jacket and the pants, I felt like I was walking neck-deep through a pool, pushing against a wall of water. A few minutes later, I was supposed to act the part of a fleeing suspect, and “run” away from a dog. I could hardly manage a respectable walk. I could feel the soggy Virginia heat on my face, but it was actually cool inside the bite suit. This luxurious damp was, I knew, lingering sweat from the bodies that had worn it during drills the day before

Finally, Staff Sergeant Ted Carlson, a handler, brought out the dog who was going to bite me, a slender Dutch shepherd named Rambo. From across the yard, I could hear Rambo’s ragged panting, the high-pitched whining and the sound of his teeth smacking together as he snapped at the air in anticipation. The sight of me in the suit had ignited the dog’s prey drive—the instinct that motivates him to chase and bite something into submission.

My chest pounded, and a small crowd of handlers, which had gathered in the training yard to watch me catch my first bite, began shouting and good-naturedly ribbing me. My brain knew that I was safe, but my body didn’t—my muscles stiffened. It was physical primordial response. It was fear.

Jakubin, tall and sturdy at 6’4”, stood with me in the middle of the yard, adjusting my stance. Before leaving me all 5’ of me there on my own, he offered one final directive. “If you get knocked down, don’t move,” he said. “I’ll come and pick you up.”

I held my breath, shut my eyes, and waited for the blow. It took Rambo under three seconds to clear the 25 feet separating us. I felt a spike of adrenaline as the dog made contact; the force of his weight shoved me back as his open mouth locked around my arm. The sensation registered from dull to crisp: pain.

To put the feel of a dog bite into perspective, it might be helpful to start with what’s familiar. Per square inch, the human bite exerts 120 pounds of pressure through 32 teeth. That’s enough to do some damage—think Mike Tyson, who managed to tear away a piece of Evander Holyfield’s ear. Dogs have 42 teeth, but the big fangs, the canines, are the real wreckers. A dog’s straight, muscular jaw is designed for meat eating, unlike a human’s mouth and jaw, where the teeth move from side to side to better grind down on things (like plants) that don’t try to run when you eat them (like me).

Studies have tried to measure the discrepancies in bite impact between different species. In an attempt to determine which species has the most powerful chomper, Dr. Brady Barr, host of National Geographic’s “Dangerous Encounters,” used a force-measuring device and found that at the extreme end of the spectrum, an alligator could produce something like 2,500 pounds of pressure. Dog bites range from forceful (an American pit bull terrier locks on at 238 pounds of pressure per square inch) to the deadly (a bullmastiff, the breed with strongest bite, bears 552 pounds of pressure per square inch).

Trainers want their dogs to get a full-mouth bite with a solid grip. But bite power depends on many things, from the obvious (how large the dog is) to the difficult to predict with regularity (the dog’s desire to bite). A weak bite happens when, say, only a dog’s front teeth catch the material. That kind of grip won’t hold for long.

I couldn’t say exactly how many pounds of pressure were crunching my burlap-wrapped arm—Rambo wasn’t huge—but I knew it wouldn’t be at the top of the spectrum. So I gritted my own teeth and forced a smile, taking a few steps around the yard. Still, Rambo had managed a good, full-mouth bite, so he remained fastened to me. Whenever I moved, I dragged him along. Jakubin encouraged me to try to pull my arm away from the dog; the resistance excited Rambo, activating his prey drive, which in turn further ignited his desire to bite. I tugged my arm for all I was worth, but Rambo’s grip only got stronger.

We repeated this move—run, jump, bite—a few more times. When I took off the suit, a marking the shape of a dog’s open mouth had already puffed pink and purple on my upper right arm. Within an hour, that marking would billow into a righteous bruise of deep blues and greens. Compared to some of the batterings I’ve seen on arms far more muscular and experienced than my own, this mark was like holding up a paper cut next to a machete wound. Nevertheless, I regarded my contusion fondly over the next couple of weeks, proud as its coloring molted into withering shades of yellow and brown.

When Rambo’s imprint finally faded and disappeared completely, I was sorry to see it go.