Double-coated dogs have two distinct layers of fur: a dense, soft undercoat close to the skin and a longer, coarser outer coat of guard hairs on top. Dozens of breeds carry this coat type, from tiny Pomeranians to massive Newfoundlands, and some short-haired breeds you might not expect are double-coated too.
How a Double Coat Works
The two layers serve different purposes. The undercoat is made of fine, soft hairs that trap air against the skin, acting as insulation. In winter, that trapped air holds body heat in. In summer, it keeps cool air close to the skin and buffers against outside heat. The outer coat, made of stiffer guard hairs, repels water, blocks UV rays, and shields against snow, dirt, and debris.
These two layers also differ at a structural level. Guard hairs have three fully formed layers within each strand, making them strong and slow-growing. Undercoat hairs are simpler in structure, with only two layers, which is why they’re softer, weaker, and cycle in and out much faster. This difference in growth speed is important to understand before making any grooming decisions.
Short Double-Coated Breeds
Not every double-coated dog looks fluffy. Several breeds have short, sleek fur that hides a surprisingly dense undercoat underneath. Labrador Retrievers are the most common example. Their coat feels smooth and close to the body, but Labs shed heavily because of that hidden undercoat cycling out throughout the year. Other short double-coated breeds include the Greater Swiss Mountain Dog, Cardigan Welsh Corgi, and Pembroke Welsh Corgi. If you’ve ever wondered why your Corgi leaves so much fur on the couch despite looking relatively short-haired, the undercoat is the answer.
Medium Double-Coated Breeds
Herding dogs commonly fall into the medium double-coat category. Border Collies and Australian Shepherds are the most recognizable examples. Their outer coats are long enough to be visibly wavy or feathered, especially around the chest, legs, and ears, while the undercoat is thick enough to handle long days working outdoors in variable weather. These medium coats require more regular brushing than short double coats because the longer guard hairs are more prone to tangling with loose undercoat fur.
Long Double-Coated Breeds
The large working breeds tend to carry the longest, most dramatic double coats. Newfoundlands, Bernese Mountain Dogs, Great Pyrenees, and Saint Bernards all have flat, water-resistant outer coats paired with thick undercoats. These breeds were historically used for mountain rescue, livestock guarding, and water work, so their coats evolved to handle extreme cold, wet conditions, and prolonged outdoor exposure. The trade-off is significant grooming needs and heavy seasonal shedding.
Arctic and Triple-Coated Breeds
Some breeds have coats so dense they’re sometimes described as triple-coated. These are the dogs bred for the coldest climates on Earth: Samoyeds, Alaskan Malamutes, American Eskimo Dogs, Siberian Huskies, and Pomeranians. Their undercoats are exceptionally thick and plush, often standing the outer coat away from the body. Samoyeds, for instance, produce so much undercoat fiber that it can actually be spun into yarn. These breeds tend to shed the most dramatically of any double-coated dogs.
Seasonal Shedding and “Blowing Coat”
Double-coated dogs typically shed year-round at a low level, but the real event happens twice a year during what groomers call “blowing coat.” In spring, the thick winter undercoat sheds out in large clumps as the dog’s body prepares for warmer weather. In fall, the lighter summer undercoat drops to make room for a denser winter layer to grow in. During these periods, you’ll see a dramatic increase in loose fur, sometimes enough to fill garbage bags.
The timing is triggered primarily by changes in daylight length rather than temperature alone. Dogs that live mostly indoors with artificial lighting may shed more evenly throughout the year instead of having two distinct heavy shedding seasons, which can make the shedding feel constant.
Grooming a Double Coat
Routine brushing is the single most important thing you can do for a double-coated dog. At minimum, a thorough session once a month keeps the undercoat from matting against the skin. During shedding season, you’ll want to increase that to several times a week.
The most effective approach uses a few different tools in sequence. Start with an undercoat grooming rake, which has long, spaced teeth designed to reach through the outer coat and pull out loose undercoat without cutting it. Work through every section of the body. Next, use a slicker brush on the thicker areas like the hindquarters and chest where fur tends to clump. A regular comb works well for the feathered hair on the backs of the legs. For mats that have already formed, a spray detangler left on for a few minutes followed by a de-matting comb can work them loose without pulling painfully at the skin. A final pass with a bristle brush smooths everything out.
Why You Shouldn’t Shave a Double Coat
It might seem logical to shave a double-coated dog in summer to keep them cool, but this usually does more harm than good. The undercoat already functions as insulation against heat, and the outer coat blocks UV radiation that can burn exposed skin. Removing both layers strips the dog of its natural temperature regulation system.
The bigger risk is permanent coat damage. Because undercoat hairs grow much faster than guard hairs, shaving creates a situation where the undercoat races back in while the outer coat barely grows at all. Brian Collins, a veterinarian with the Cornell Riney Canine Health Center, has noted that shaving a double-coated breed can damage hair follicles and result in poor regrowth. In many cases, the guard hairs never fully return. What grows back is a bristly, matted texture dominated by undercoat, which is actually worse at regulating temperature and more prone to tangling than the original coat was. If your double-coated dog seems overheated, regular brushing to remove loose undercoat, access to shade and water, and trimming (not shaving) of longer feathering around the legs and belly are all safer options.