Angus is in the front hallway of our house, nose to the ground like a bloodhound, sniffing like mad. He sniffs along the rug and then sticks his head inside a cardboard box and sniffs that. Then he moves on, sniffing in the corner behind the front door (oh, man, I must dust!), sniffing the bookshelf, sniffing the top of the radiator. He is as methodical as a detective.

Then he heads up the stairs.

On the landing, he first sniffs the windowsill, then each step, edge to edge. He stops. He looks at me. Found it!

"Yes!" I yell. He paws at the spot between the spindles of the banister where I have wedged a small metal box. It took him about two minutes of vigorous sniffing to find.

"Yes!" I say again, and he races down the stairs to me, tail wagging. I shower him with treats. And then I hide it again.

We have been playing this game — "nose work," it's called — for only a few weeks but Angus caught on fast. The object is simple: I hide a small perforated box that contains half a Q-tip sprinkled with scented oil, and Angus finds it by following his nose.

It's a game to him, and a fun one — he particularly loves the shower of treats every time he finds the box — but it's also great exercise for his brain and, really, for the rest of him too.

Dogs learn about the world through their noses. Their epithelium (nasal tissue) is 30 times larger than humans', and way more powerful — they have hundreds of millions of olfactory neurons, while we have a paltry 12 million.

But living in houses, in the city, they don't always have the opportunity to fully exercise that part of their brain.

Over the years, a number of dog trainers have suggested nose work for Angus — he's a nervous dog, highly reactive, and they told me that nose work builds confidence. He is also a very visual dog — it's the Border collie in him, I think — and nose work teaches him to use his nose instead of relying on his eyes.

So I finally gave it a try. There are classes in nose work, but in this time of COVID, and with a dog who is afraid of humans and other dogs, that seemed fraught. So, instead, I read about it online and watched a couple of YouTube videos. Turns out that it was just as easy as it sounds.

I started by holding the scent box in one hand and a handful of treats in the other. Of course he tried his best to pry my treat-hand open but eventually gave up. He tapped the box with his nose, and I said, "Yes!" and gave him a treat. It didn't take him long to understand that touching the box was his ticket to food. Now we start every session that way.

At first, I placed the box a few feet away from him, out in the open, and said, "Find it!" We've quickly worked our way up to my hiding it inside boxes, under blankets, on porches and up the stairs.

Nose work hasn't stopped Angus from being reactive. (Nothing, I fear, will ever stop that.) But I see other benefits. For one thing, he clearly loves it. And on walks he meanders, sniffing the ground instead of scanning the horizon for squirrels.

This morning, he was so interested in the scents along the edge of the path that he failed to notice the full-grown deer that wandered up behind us. I was able to usher him away with no barking. I'm going to call that a win.

Laurie Hertzel is not a dog expert, just a dog lover. She has been writing about her reactive rescue dog, Angus, since he was a puppy. Read all the columns at www.startribune.com/puppy.