Shedding Season and Skin: What's Normal and What Isn't

Seasonal shedding thins the coat all over and leaves normal-looking skin underneath. If you can see skin because the coat has thinned evenly across the body, and that skin is its usual color with no flaking, redness, or sores, that's a heavy shed. If you can see skin because there's a bald patch, or the skin under it looks angry, that isn't shedding at all — it's hair loss, and it needs a vet rather than a better brush.

That distinction is the whole article. Everything below is how to tell which one you're looking at, and what to do in each case.

What a normal seasonal shed looks like

Shedding is triggered mainly by changes in daylight and temperature, and for seasonal shedders the heaviest periods are spring and fall. A typical blow runs a few weeks to a couple of months.

During it, you should expect:

The whole coat gets lighter rather than developing bald spots — on a double-coated dog the undercoat comes out while the guard hairs stay, so the texture may look flatter or a bit patchy, but nothing goes absent in a defined area.

Undercoat that comes away easily. Soft, fluffy, wool-like — it releases when you brush and doesn't need pulling.

Skin that still looks like skin: whatever color your dog's is normally, with no redness, no scaling, no bumps, no smell.

And a dog who's otherwise themselves — normal appetite, normal energy, no more scratching or licking than usual.

Thin coat plus healthy skin plus a normal dog is a shed. It looks alarming and isn't.

What isn't normal

The AKC's chief veterinary officer, Dr. Jerry Klein, describes alopecia as a common condition referring to thinning hair or bald areas — and it comes from allergies, skin infections, endocrine disease, hormonal and genetic factors, or environmental conditions. None of those are things a grooming routine fixes.

Take your dog to a vet if you see:

Sign	Why it matters
Bald patches, or thinning in one defined area	Seasonal shedding is diffuse. Localized loss points to a specific cause
Symmetrical loss on both sides of the body	A pattern often associated with hormonal or endocrine problems
Red, inflamed, scaly, greasy, or smelly skin	Skin disease or infection, not coat turnover
Scratching, licking, or chewing at one spot	Parasites, allergies, or pain. The licking itself then makes it worse
Sores, scabs, or open skin	Needs treatment, and brushing over it will hurt
A sudden dramatic increase in hair loss	Worth ruling out an underlying cause
Heavy loss continuing well past two months	Longer than a typical seasonal blow

Any of these with a dog who's also off their food, drinking more than usual, or low-energy moves the visit up the priority list. Coat and skin are often the first visible sign of something systemic.

Cats are a different picture

Cats shed seasonally too, and they groom the loose hair out themselves — which is why hairballs are more frequent in shedding seasons, as Cornell's Feline Health Center notes.

But bald patches on a cat usually have a specific cause worth knowing about: overgrooming. Cornell is direct that licking to the point of hair loss is abnormal, and that bald skin is then more vulnerable to sunburn, frostbite, and other damage. Worse, if the cat's rough tongue breaks the skin, infection follows and the infection intensifies the licking, setting up a cycle.

The important part is what to rule out first. An owner can check for fleas, lice, and matted fur. Beyond that, Cornell says a veterinarian should intervene — checking for parasites, flea infestation at the tail head, pollen or food allergies, neurological disease, and pain from conditions like disc disease or anal sac impaction. Stress is a real cause of overgrooming, but it's the diagnosis you reach after ruling out medical causes, not the one you assume first.

So a cat losing hair on the belly, inner thighs, or one flank isn't shedding heavily. That's a pattern with a cause.

What grooming can and can't do here

Brushing is genuinely useful during a normal shed. It moves hair off the animal before it reaches your house, prevents matting, and — the part people don't think about — it's the most reliable way you'll notice a skin change early. You have your hands on the dog every day, working section by section. Most owners find lumps, hot spots, and flea dirt during grooming rather than during a cuddle.

A fine-toothed comb is the better tool for that kind of looking. A self-cleaning deshedding comb parts the coat as it works — its teeth are 0.8 inches (2 cm) deep with rounded tips designed not to scratch — so you're seeing skin rather than just moving over the top of the coat. On sensitive animals, including cats, that rounded-tip design is what makes daily handling tolerable.

But no grooming tool treats a skin problem. If you've found redness, a bald patch, sores, or a spot the animal won't let you touch, put the brush down. Brushing over inflamed skin hurts, can spread an infection, and delays the thing that would actually help. The comb is how you find it. A vet is what you do about it.

Also worth saying plainly: don't respond to alarming shedding by shaving. The AKC notes that shaving doesn't eliminate shedding, damages the topcoat, and increases the risk of skin issues and sunburn.

Frequently Asked Questions

Q: My dog is shedding so much I can see skin through the coat on his back. Should I worry?

A: Look at the skin, not the coat. If the thinning is even across the body and the skin underneath looks normal — usual color, no flaking, no redness, no sores — that's consistent with a heavy seasonal shed, which can genuinely thin a double coat noticeably. If the thin area has a defined edge, or the skin looks irritated, that's worth a vet visit.

Q: Can stress cause a dog or cat to lose hair?

A: It can contribute, and it's a recognized cause of overgrooming in cats especially. The catch is that stress is a diagnosis of exclusion — parasites, allergies, infections, hormonal problems, and pain all cause similar signs and all need ruling out first. Assuming it's stress without that check is how treatable problems get missed for months.

Q: Does diet affect shedding?

A: Nutritional problems are among the recognized contributors to poor coat and excessive hair loss, so a genuinely inadequate diet shows up in the coat. That doesn't mean a supplement fixes heavy seasonal shedding in a dog already eating a complete diet — the seasonal part is driven by daylight, not nutrition. If you're considering a diet change because of coat problems, raise it with your vet rather than switching first.

Q: How quickly should hair grow back after a bald patch?

A: It depends entirely on the cause, which is the reason to get a diagnosis rather than wait it out. Some causes resolve once treated and the coat regrows over weeks to months; others need ongoing management. A bald patch that isn't refilling after several weeks is a reason to go back, not a reason to be patient.

Sources

• American Kennel Club — Hair Loss in Dogs: Signs, Symptoms, and Treatments (https://www.akc.org/expert-advice/health/hair-loss-in-dogs/)
• American Kennel Club — Dog Shedding: When Dogs Shed Most and How to Manage It (https://www.akc.org/expert-advice/health/managing-dog-shedding/)
• American Kennel Club — How to Groom a Double-Coated Dog (https://www.akc.org/expert-advice/health/how-to-groom-a-double-coated-dog/)
• Cornell Feline Health Center — Cats that Lick Too Much (https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/cats-lick-too-much)
• Cornell Feline Health Center — The Danger of Hairballs (https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/danger-hairballs)