"In my opinion, double-coated breeds should never be shaved unless there's a medical reason to do so, as their undercoats act as an excellent insulator against the summer heat," writes veterinarian Karen Becker. "It seems counterintuitive that an extra layer of fur would help a dog stay cooler, but it does. Air is a natural insulator, and air trapped between the hair follicles and hairs on your pet's body does a really efficient job of keeping body temperature in balance."
So, while it may be tempting to want to help your double-coated dog shed a few layers this summer, it's important to keep in mind that their fur is there for a reason.
Even dogs with single coats likely do not need to be shaved to stay cool, but for folks who choose to do so, it's recommended to leave at least an inch of hair to protect them from getting a sunburn.