The Great Fall Fur Fall: The Science Behind Why Dogs Shed

Why your dog may suddenly seem to be leaving half their coat around the house, and what you can actually do about it.  If it feels like your dog suddenly starts producing enough loose hair to build a second dog every fall, there’s a reason.

Shedding isn't simply hair "falling out." A dog's coat is constantly going through a biologic cycle of growth, transition, rest, release, and replacement. For many dogs, changes in daylight and temperature influence that cycle, which is why spring and fall can bring a dramatic increase in the amount of hair coming out of the coat.

And while we can't stop a healthy dog from shedding, good coat care can make the process much more manageable.

First, How Does Dog Hair Actually Grow?
Hair grows from follicles within the skin. Unlike human hair follicles, canine follicles are often compound follicles. A central primary hair can be surrounded by multiple smaller secondary hairs emerging through the same opening in the skin. Merck notes that a canine compound follicle may have a central hair surrounded by 3 to 15 secondary hairs.

Those different hairs have different jobs.

The outer or primary hairs are commonly called guard hairs. Beneath them, many breeds have finer secondary hairs that make up the undercoat.

That undercoat isn't just there to make your vacuum cleaner miserable. The coat protects the skin from physical and ultraviolet damage and plays a role in temperature regulation. Air trapped among the secondary hairs provides insulation, particularly in cold-weather coats.

This is why coat type matters enormously when we talk about shedding.

The Hair Growth Cycle
Individual hairs don't grow forever.

Veterinary dermatology divides hair growth into stages. Anagen is the active growth phase. Catagen is a transitional stage. Telogen is the resting phase of mature hair. Eventually old hair is released as the follicle cycles and new growth develops.  In other words, normal shedding is part of normal hair replacement.

The Merck Veterinary Manual specifically notes that the development and growth of new hair is accompanied by shedding of old hair. If a dog is shedding but isn't developing bald patches or symmetrical areas of hair loss, that shedding may simply be part of normal coat replacement.  So why does so much of it happen at once?  One major trigger is photoperiod, or the amount of daylight an animal is exposed to.

Hair growth can be influenced by nutrition, hormones, environmental conditions, temperature and changes in daylight. Merck notes that dogs normally shed in early spring and early fall and may shed in response to changes in temperature or sunlight.

🍂 The Great Fall Fur Fall
Fall shedding can seem backward.  Shouldn't a dog be keeping its hair because winter is coming?
Not exactly.

For dogs with seasonal coats, the existing coat needs to make way for the coat appropriate for the next season. VCA notes that dogs with thick coats consisting of guard hairs and a fine undercoat can undergo significant seasonal shedding, with large amounts of undercoat being released during those periods.
So all that hair you're finding on your couch isn't necessarily your dog's winter coat disappearing.

You're watching the coat transition.

Why Does My Dog Shed All Year?
This is where modern life complicates things.  Dogs don't live outside according to natural daylight and temperature cycles anymore. Most of our dogs live inside heated and air-conditioned homes and spend their evenings under artificial lighting.

VCA notes that while seasonal shedding is influenced by temperature and daylight, dogs spending much of their lives indoors under relatively consistent temperatures and artificial light may shed throughout the year.  So you can absolutely have both: a dog that sheds year-round AND a dog that gets significantly worse during seasonal coat changes.

Breed and genetics also make a huge difference. Some continuously growing coats behave very differently from the dense double coats seen in breeds such as Huskies, Malamutes, German Shepherds and many Retrievers.

Brushing Doesn't Make Your Dog Shed More
This is something we hear occasionally when a shocking amount of hair comes out during grooming.
"Did brushing make all that hair come out?"  The brush didn't create the shedding.

We're removing hair that has already entered the release portion of its natural cycle and helping it leave the coat instead of remaining trapped among the surrounding hairs.

During heavy seasonal shedding, regular brushing can help remove that loose, dead hair. VCA specifically recommends regular, even daily, brushing during intense seasonal shedding to help remove the excess coat.  For dense coats, this becomes particularly important because loose undercoat doesn't always immediately fall onto the floor.  Some of it stays inside the coat.

That's when thorough brushing and professional deshedding can make an enormous difference.

Healthy Skin Matters, Too
A beautiful coat starts underneath the hair.

The skin and coat form an important protective barrier, while sebaceous glands produce sebum, an oily substance that helps keep the skin soft and pliable and contributes to coat condition. Nutrition, hormones, disease, medications and environmental factors can all affect hair health and growth.

This is one reason we approach grooming as skin and coat care, rather than simply making a dog smell good and cutting some hair. 

It's also part of why we use professional products from IV San Bernard in our salon. For example, IV San Bernard's Mineral Red Derma Plus is formulated with keratin and nettle and is designed to condition and nourish the skin and hair following cleansing.  The product doesn't change the normal biology of seasonal shedding. Our goal is to support the skin and coat while physically removing coat that is ready to come out.

Can You Stop Shedding?
For a normally shedding dog?  No, and we wouldn't want to.  Shedding is a normal biological process. What we can do is manage it.

Regular grooming can remove loose coat in a controlled setting, keep the remaining coat clean and easier to maintain, help prevent tangles and compacted coat, and give us an opportunity to actually see and feel the skin underneath all that fur.  And yes, it can mean considerably less of that loose hair ends up rolling across your living room like a tiny tumbleweed.

🐾 Need Help Between Full Grooms?
We've also added a simple option for dogs who don't need another full bath but do need some help keeping up with their coat between appointments.

Our New Quick Groom
Our Quick Groom is $30 and includes:  Dry shampoo + a thorough brush-out

It's a great option between regular grooming appointments, particularly during seasonal shedding, or for owners who have difficulty keeping up with brushing at home.  No full bath. No full groom. Just a freshen-up and some dedicated time getting that loose coat out.

When Shedding Isn't "Just Shedding"
There is an important difference between normal shedding and hair loss.

A dramatic amount of loose hair can still be normal, particularly during a seasonal coat change. But bald areas, symmetrical thinning, significant itching, redness, scaling, skin changes, broken hair, sores or an unusual change in your dog's normal shedding pattern deserve more attention.

Excessive or abnormal hair loss can be associated with infections, parasites, allergies, hormonal disorders and other medical conditions. For example, hypothyroidism can cause coat changes including excessive shedding, delayed hair regrowth and symmetrical thinning or hair loss.

Those aren't grooming problems.  They're veterinarian problems.

If we notice something during your dog's groom that doesn't look like ordinary coat turnover, we'll let you know. We don't diagnose skin or coat conditions at The Blue Hound, but regular grooming gives us a pretty unique opportunity to get our hands and eyes on your dog's skin and coat from nose to tail. That means we can often spot when something looks or feels different and recommend checking in with your veterinarian.

And trust us when we say, we see A LOT of dog coats. Fluffy ones, wiry ones, curly ones, double coats, barely-there coats, and coats that somehow produce enough loose hair to create an entirely new dog. All of that hands-on experience has made us pretty darn good at knowing what looks normal for a coat and when something deserves a second look.

The Bottom Line
That fall explosion of fur isn't your dog's coat malfunctioning.  For many dogs, it's doing exactly what it was designed to do.

Changes in daylight and temperature influence the canine hair cycle. Old coat is released while new coat develops, and double-coated breeds can release substantial amounts of undercoat during seasonal transitions. Dogs living primarily indoors may also shed throughout the year because their environment doesn't follow natural outdoor light and temperature patterns as closely.

You can't eliminate normal shedding.  But with healthy skin, appropriate coat care and regular removal of loose hair, you can make the Great Fall Fur Fall a whole lot more manageable.  And maybe save your vacuum cleaner in the process.

The Blue Hound
Premier Canine Care
Longview, Washington

Sources & Further Reading
The veterinary information in this article was researched using the Merck Veterinary Manual's canine skin and coat resources, Merck's veterinary discussion of the animal hair-growth cycle, and VCA Animal Hospitals' veterinary guide to canine grooming and coat care. Product-specific information regarding the Mineral Red line comes directly from IV San Bernard's Derma Plus professional product information.