Q: Why do indoor cats and dogs grow and shed a seasonal coat even if they never go outside?
A: Animal coats respond to many factors, said Sandi Sawchuk, a clinical instructor at the School of Veterinary Medicine at University of Wisconsin-Madison. "It's not just temperature. Hair goes through these natural cycles — much like us. Hair falls out, and new hair grows in."
"Cats, and dogs with undercoats, tend to get a thicker coat in winter, but light can be a huge factor for indoor animals. As the days get longer in spring, they will shed to create the summer coat. They don't even have to go outside — the light can come through a window. Even artificial light can force them to enter their normal shedding cycle."
There are other factors, Sawchuk adds. "Some pets shed constantly; other don't. It can be related to their hormonal status. The heat cycle, or a pregnancy, may cause a change in fur."
Veterinarians are intimately familiar with the fact that fur can respond to stress.
"Attached to every single hair is the erector pili muscle, which makes it stand up," said Sawchuk. "In dogs and cats, when they are a little nervous, these muscles contract, and they end up dumping a lot of fur. I just saw a golden retriever, and I'm wearing black, and I'm covered in fur. It never fails."
Moral of the story: Unless you have a non-shedding breed, like a poodle or a schnauzer, whose hair continues to grow, you'll be needing to brush your domestic animals right about now.
— Provided in cooperation with University Communications