It’s 30 degrees in Grand Rapids, Mich., and Mara Peverini is getting ready to head out the door. She bundles up in a sweater, a puffer jacket, boots and a scarf.

Then she does the same for her dog. “She can spend an hour outside in the snow, as long as she’s dressed properly,” Peverini, 31, said of her 10-year-old Chihuahua, Layla. “But the moment I underdress her, we walk five feet and she refuses to keep going.

” “We alternate with the colors and styles,” Peverini said. Winter outerwear has become increasingly popular for pets. Clothing brands for humans have started selling doggy lines, and pet parents are wearing matching parkas with their pooches.

While it’s adorable, and sometimes hilarious, for canines to wear winter clothes, it’s actually important for many dogs to keep them safe in cold weather, experts say. “There are several factors that go into whether a dog needs winter protection,” said Nancy Kay, a veterinarian and author of “Speaking for Spot.” Key factors include climate, breed, age, size, health and hair coat.

“Any of the arctic breeds - Siberian huskies, malamutes, Samoyeds - those are dogs that were bred for snow, and so they really don’t need protection,” Kay said. “If you picture the opposite end, like a whippet, with skinny legs and a light hair coat, those dogs definitely need protection.” When humans domesticated wolves about 40,000 years ago, they did not need people to wrap them in parkas to keep them warm.

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