Why Some Dogs Shed More: The Genetics of Shedding

All dogs shed, because every hair grows, rests and eventually falls out. How much a dog sheds depends largely on a few genes: the furnishings gene, a second gene called MC5R, and whether the dog has a dense undercoat. Low-shedding breeds such as the Poodle carry two copies of the furnishings variant, while heavy shedders such as the Akita and the Alaskan Malamute have no furnishings and carry the original version of MC5R.

The short version

• Every dog sheds as part of its normal hair-growth cycle.
• Two genes are linked to shedding: RSPO2, the furnishings gene, and MC5R.
• An undercoat adds seasonal shedding, and a separate region of the genome decides whether a dog has one.
• Curly coats hide shed hair rather than stopping it.
• "Non-shedding" and "hypoallergenic" are marketing terms, not genetic categories.

Two genes linked to shedding

A 2016 study of more than 4,200 dogs, one of the largest dog genetics studies of its time, linked shedding to two genes: RSPO2, which also causes furnishings, and MC5R, which also influences coat length. Breeds fell into a clear pattern:

So furnishings matter most: the minimal-shedding breeds carry two furnishings copies. Among dogs without furnishings, MC5R helps separate moderate shedders from heavy ones. Our guide to furnishings explains how that gene is inherited.

Single coats and double coats

Some dogs have a single coat of hair, while others have a double coat: a soft, dense undercoat beneath longer guard hairs. A 2019 study found a region of the genome strongly associated with whether a breed has an undercoat, and noted that the double coat, which wolves have too, is thought to be the original state.

Double-coated dogs shed their undercoat heavily when the seasons change, often called blowing coat, and they shed steadily the rest of the year. The undercoat is insulation, which is why the American Kennel Club advises against shaving double-coated dogs: brushing out the loose undercoat works better. Our guide to the best dogs for Canadian winters explains how double coats help in the cold.

Why curly coats seem not to shed

Curly and wavy coats catch loose hairs instead of dropping them, so curly dogs leave less hair on floors and furniture. The hair is still shed, and it builds up into mats unless it's brushed out. Our guide to curly coats explains the curl gene, and our guide to doodle shedding covers how these genes combine in doodles.

Other things that change shedding

Genetics sets the baseline, but other things move it:

• The seasons: most dogs shed more in spring and fall, especially double-coated ones.
• Age and coat changes: a puppy coat gives way to an adult coat, and older dogs' coats can change too.
• Grooming: regular brushing catches loose hair before it lands on the floor.
• Health: sudden, patchy or very heavy hair loss, or itchy, red or flaky skin, is a reason to see your vet rather than a genetics question.

Shedding and allergies

Low shedding isn't the same as low allergen. In a study of the main dog allergen, dogs of so-called hypoallergenic breeds, including Poodles and Labradoodles, had higher allergen levels in their hair and coat than other dogs, and airborne levels in their homes were no different. Another study found no difference in home allergen levels between homes with "hypoallergenic" dogs and other homes. If someone in your home has dog allergies, spend time with the specific dog first and talk to an allergist.

How a DNA report shows shedding

The PuppyGenes physical appearance section includes a shedding prediction based on MC5R, alongside the furnishings prediction based on RSPO2, each with its own confidence. The shedding result is a reported tendency, not a measurement of how much hair your dog sheds. In our public example reports, both Juno and Marley are predicted to have "likely light shedding (furnished coats shed little regardless)", which matches what the research found about furnishings.