The other night my husband was playing with our puppy when he said, "What's that lump behind his ear?"

Horrified that he had found a tick, I went to investigate. But it was thick and lumpy and way too big to be an insect. We peered and prodded and couldn't figure it out. Our sweet dog whined when we poked too much, and I was ready to rush to the vet, convinced he had a horrible growth.

But then I consulted the Internet. Turns out (duh) our long-haired pup had a mat. No tumor. No tick. But a thick ball of hair, which had accumulated in a tight knot right behind his ear. I tried coaxing it free like I remember my mom doing with my tangled mop years ago. I tried a little conditioner. Finally, I went to work with some tiny fingernail scissors and a little slicker brush.

It's not that we don't groom our dog. I have all sorts of brushes and combs and a fancy gadget that's supposed to remove excess undercoat. Every time I use it, I feel like I could make a new dog with the puffs of hair that come billowing out. But our last sweet boy was a Jack Russell terrier. He had teeny little slick hairs and was incredibly low-maintenance. I had never seen a mat before now.

And now I find out that these ear mats might be our fault. When I mentioned it to the groomer at my vet's office, she said — as strange as it sounds — that many people are petting their dogs the wrong way.

Apparently, we have a tendency to rub and massage our little guys behind the ears because we love them so much. And those long wispy hairs form a nest of a mess. Instead, we should pet them in long raking moves so we don't tangle the hair.

"Some dogs have a really fine undercoat and around their head it's really soft so we tend to play with their hair there," says Lori Bierbrier, DVM, staff veterinarian with the ASPCA. (For the record, she says she's seen several cases of panicky dog and cat owners like me who thought a mat was something so much worse.)

"I don't think we totally make (a mat) happen by petting them, but we can add to it," she says. "Like some people have the habit of twirling or twisting their hair, it's like that."

That doesn't mean we should stop petting our pets, obviously; just be more vigilant in preventive care with regular grooming.

dog owner brushes her Shetland sheepdogGrooming your dog regularly can help prevent the formation of mats. (And sometimes your dog might actually like it.) (Photo: allanw/Shutterstock)

Mats 101

Mats usually form whenever there's rubbing or some kind of movement, says Bierbrier. That's why it's common for dogs to get mats between their legs, near their tail, by their collars and behind their ears. If you work the knots out early, they're relatively harmless and not too uncomfortable for your pet. But as they grow, they can cause irritation and lead to problems like bacterial and fungal infections. If they're on the legs, they can make it difficult for the dog to move. If mats get too big, tight and close to the skin, a groomer or a vet may have to remove them.

The ASPCA website suggests using a rubber brush or slicker brush on smooth, short-coated dogs. Use a slicker brush, then a bristle brush on dogs with short, dense fur that mats easily. For dogs with long hair, remove tangles daily with a slicker brush. Then brush with a bristle brush and comb if necessary. Don't use a scissors (like I did) because you can cut your pet's skin if you get too close, especially if the dog fidgets.

There's a trick or two you can learn at home, says Jean Donovan of Laurel, Delaware, who has been grooming dogs for more than 35 years. She agrees that petting gets some of the blame, but says the ears are just prone to matting.

"I call it a 'high traffic area.' They perk those ears up for every sound plus, there's always the good ol' scratch-behind-the ear habit," she says.

Donovan suggests rubbing a little cornstarch on your fingers, then rubbing the mat. The slippery starch will help make the mat easier to work out with a bristle brush and comb.

Here's a great how-to video from a dog groomer who shows how to get rid of tangles and mats. (You watch it while I go brush my dog.)

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Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.