Different Types of Dog Coats: The Double Coat

The term "double coat" literally means the dog grows two distinct types of hair from the same follicle. The outer layer consists of guard hairs, which are tough, coarse, and highly pigmented. These repel water, dirt, and UV rays. The inner layer is the undercoat, a dense, soft, downy fleece that sits right against the skin to provide maximum insulation. Together, they create an impenetrable barrier against harsh elements.

The most common misconception is that a thick double coat makes a dog hotter in the summer. In reality, the double coat acts exactly like the insulation in your house. In the winter, the undercoat traps body heat to keep the dog warm. In the summer, the dog sheds the heavy undercoat, allowing cool air to circulate against the skin, while the remaining guard hairs act as an umbrella, blocking the sun's scorching rays from reaching their delicate epidermis.

While double-coated dogs shed mildly year-round, they experience a massive, systemic shed usually twice a year (spring and fall) triggered by changes in daylight and temperature. This is known as "blowing coat." During this time, the undercoat detaches in massive clumps. If these clumps are not brushed out, they weave into the guard hairs, creating a painful, solid pelt that traps moisture and invites skin infections.

You cannot groom a double coat with a standard human hairbrush. You need an undercoat rake (with long, smooth tines that reach through the guard hairs to pull out loose down) and a high-quality slicker brush. Caution: Be incredibly wary of bladed deshedding tools (like the Furminator). While they look like they pull out a lot of hair, they actually cut and splinter the healthy guard hairs, irreparably damaging the coat's texture over time.

If your dog is blowing their coat, brushing alone will take hours. The professional secret is the deshedding bath. Warm water and specialized deshedding conditioner loosen the dead undercoat in the tub. Then, the groomer uses a high-velocity dryer to literally blast the detached undercoat out of the guard hairs before a brush even touches the dog. It saves the dog's skin from brush-burn and cuts shedding in the home by 80%.