Why does my cat shed so much?
I’ve read that the average cat has about 40 million hairs, give or take a few million, although I’m not sure anybody has ever actually counted.
Some days, when the cat-fur tumbleweeds are tumbling down the hall, and it’s hard to tell that my “nice” black slacks are actually black, I’m convinced that cats can shed half that number of hairs overnight.
How much shedding is “normal”? Why do some cats seem to shed so much? When should I worry about my cat shedding? We will answer all of these questions and more in this blog post.
All about cat hair
First, let’s talk a little bit about cat hair.
Cats have a lot of fur. In fact, when we talk about cat hair, we usually refer to it as fur – which just means densely packed hairs. It’s OK to use either term.
Cats have between 60,000 and 120,000 hairs in just about every square inch of their bodies. That’s a lot of hair. Cats need it all – fur is part of the “integumentary system,” which is the largest organ in the feline body. The integumentary system includes skin in all its layers, hair, and nails, which together form a protective wall between the outside world and the inside of the cat.
Types of cat hair
Cat hair comes in four (or five-ish) types, and not every cat has every type:
Down hairs are appropriately named. They’re the soft, fluffy hairs that provide warmth, much like the goose down we use to make our warmest comforters and puffy winter coats.
Viewed under a microscope, down hairs appear wavy or crimped, which helps make them extra-effective as insulators. Note that down hairs are the ones closest to the skin and this is the fur layer that tends to get matted if a cat isn’t regularly groomed.
Some cat breeds do not have a down layer, such as the Javanese. Some cats, such as the Cornish Rex, only have a down layer of fur.
Awn hairs come between the down layer and the guard layer, if a cat has all three. Awn hairs help protect the delicate down hairs, and they also provide some additional insulation. They are typically longer than down hairs, but shorter than guard hairs.
Turkish Van cats have only an awn layer.
A cat with a guard-hair layer has got his own water-repellent windbreaker on all the time. Guard hairs tend to be stiffer and longer than awn or down hairs and they can keep wind and rainwater from penetrating to a cat’s skin. Guard hairs are typically straight and taper toward the tip, but have tiny barbs along their length that explain why they stick to our clothing.
The long hair in longhaired breeds, such as the Persian, are extra-long guard hairs.
Whiskers, also called vibrissae, are long, thick, sensitive hairs that emerge from the muzzle, cheeks, eyebrows, and wrists. Read more about their purpose in, “Why do cats have whiskers?”
Vellus hairs are sparse, baby-fine hairs, like those found on the so-called hairless bodies of cats like the Sphynx. We mostly-naked humans have vellus hairs, too.
How does cat hair grow?
To understand shedding, you need to understand how cat hair grows.
Individual hairs have their own growth cycle. Each strand is in its own little world, going through its own cycle at its own pace. Scientists would say that cat fur undergoes “asynchronous growth,” which just means that the hairs don’t coordinate their cycles. If they did, your cat would periodically shed himself bald.
There are four phases to the feline hair growth cycle. We used to think there was only three, but scientists discovered that shedding is actually a separate phase from the others. The hairs undergo specific changes that cause them to finally drop off a cat’s body. That being said, we still don’t understand the exact mechanics of shedding.
Feline hair growth cycle
When a cat’s hair is in anagen mode, it is growing. The hair bulb is very active and located deep in the skin. A hair in the anagen phase is difficult to remove.
The catagen phase is short-lived. A hair in catagen mode stops growing and the follicle shrinks.
Telogen is a hair’s resting phase. The bulb is closer to the surface and can be easily removed.
Exogen is the shedding phase. A scientific study of mouse hair showed that the bulb of the hair in this phase becomes shrunken, irregular, and nearly lifeless.
When do cats shed?
Do I really need to answer this question? If you live with a cat, the question you really want answered is, “When DON’T cats shed?” (The correct answer is: never.)
Shedding would normally be tied to seasonal changes in sunlight. But cats who live indoors with us, whether full time or part time, are living with “fake seasons” from the point of view of their fur. We air condition our houses in summer. We heat them in winter. We turn the lights on and off at all times of the day and night.
Cats who live outdoors, fully subject to the patterns of nature, typically shed big twice a year. When the amount of daylight starts to wane in fall, a cat’s brain sends a signal to the hair follicles that says, “make way for a thicker, fluffier, heavier winter pelt.”  In spring, a cat’s body sheds that extra fur to prepare for summer.
There are other factors that contribute to shedding in addition to sunlight (and temperature). Genetics and nutrition also play a role. And even cats who live outdoors permanently, do shed hairs all year round, in addition to those two big seasonal sheds.
Why do cats shed?
Even though a strand of hair itself is not alive (it’s made of a tough protein called keratin), the bulb at the bottom of the strand, inside the hair follicle, contains living cells. And living things don’t live forever.
Shedding is how a cat’s body gets rid of old, ragged, dead hair to make way for fresh, new hair that can best perform its insulating and protective duties.
How does shedding happen?
Exogen hairs, which are ready to separate from a cat’s body, probably just drop off.
But sometimes a cat will shed a bunch of hair all at once, such as at the vet’s office. We don’t know the exact process by which a cat’s body releases these hairs simultaneously, but we believe that tiny arrector pili muscles, which are connected to the hair follicles, are triggered when cat is stressed. Telogen hairs, which were ready to be shed anyway, are suddenly freed.
By the way, these arrector pili muscles are the same muscles that contract to cause a cat’s hair to stand on end, as when a cat is arching her back.
How do you know if your cat’s shedding is normal?
All cats have their own shedding cycles. Some cats shed so much you can hardly believe there is anything left on the cat. Others slough off just a little. Both extremes can be normal.
How do you know if your cat is shedding normally?
Look at your cat’s hair coat. A cat with normal shedding and growth cycles will maintain a soft, silky texture to the fur.
If your cat’s coat is ragged, dirty, or thin, it could be a sign that something is wrong. Bald spots or inflamed skin under the hair are also symptoms to worry about. If your cat is vomiting up more hairballs than usual, it’s a cue that your cat is not shedding normally.
What can cause abnormal hair loss?
There are many things that can cause a cat to lose an abnormal amount of hair, or to lose hair in an abnormal pattern. Here are some potential causes of unhealthy hair loss in cats:
Bacterial or fungal microorganisms that make their way beyond the skin’s outer protective barrier (perhaps through a scratch or bite) can grow and multiply within the skin and destroy hair follicles, causing hair loss.
Skin infections usually present with other symptoms that your vet can identify and treat. For example, ringworm – which is a fungal infection, not a parasite – is a leading cause of hair loss in cats. Aside from hair loss, it typically shows up as circular, red, flaky patches of skin.
Parasites, such as mites and fleas, can be the cause of hair loss in cats in a number of different ways.
Parasites can damage the hair follicle, directly causing hair loss. Parasites can also carry bacteria, and indirectly cause hair loss through a skin infection.
But the activity of the parasites on your cat’s skin can drive them crazy, causing them to scratch their own hair right out. Some cats are actually allergic to flea saliva, and the associated itching and scratching can lead to extreme hair loss.
(For more information about fleas, read, "My cat has fleas! What should I do?")
Grooming is usually a healthful activity. Grooming helps a cat rid his coat of shed hairs to prevent matting, and can keep the coat and skin clean and healthy. But there can be too much of a good thing and overgrooming can be a cause of hair loss.
It’s such a big topic that I’ve written a separate post about it: “Excessive grooming in cats.”
Like humans, cats can be allergic to their food, to something in their environment, to household or pet products, to biting insects, and parasites (see above). To ease the itch from an allergic reaction, a cat may literally scratch and lick their own hair away.
Excessive shedding is a potential side effect of certain kidney, liver, thyroid, and adrenal gland diseases, as well as feline flu and cancer. If you are unable to identify a simple explanation for hair loss in your cat, a visit to your vet will enable you to rule out or rule in a more serious cause of excessive of shedding in your cat.
Nutrition matters to a cat’s body, and every calorie really does count. In fact, 30% of a cat’s protein intake goes directly to maintaining a cat’s skin and fur. If the food your cat is eating doesn’t have enough protein, or if the proteins are hard to digest, or if other nutrients are missing, a cat’s coat will suffer. Hairs can become thinner and break right off.
Cats need the right amount of vitamins E and A to be able to produce the keratin protein that makes up hair. Without the right amount of zinc, hair growth will suffer, too.
Inability to groom
There are a number of conditions, some of which are preventable, that can keep a cat from properly grooming herself.
A cat who is overweight, for example, may struggle to reach all of her body parts during a grooming session. A cat with arthritis or other joint disease may be unable to groom properly due to the pain it causes.
Cat who are healthy and fastidious groomers typically catch a lot of loose hairs with their own tongues. These shed hairs may end up in their feces or in a hairball. But cats who are unable to groom properly may leave lot of these loose hairs on carpeting and furniture instead.
So, it may appear that your cat is shedding more than normal, even if they are not.
Pregnant cats, or cats who are nursing little ones, will shed more due to hormonal changes and the loss of minerals and calcium that go to supporting all that new life. Some cats will also lose the fur around their nipples, presumably to make it easier for the babes to nurse.
This kind of shedding is normal. You can support your pregnant or lactating cat by feeding her a good quality kitten food, which offers more calories and a higher protein content, and letting her eat as much of it as she likes.
See a vet if you can't get to the bottom of your cat's sheddingThere are so many potential reasons why a cat may be losing too much hair, that it can take a real detective (with a whole bunch of lab equipment) to get to the bottom of it.
If your cat seems to be losing too much hair, don’t wait it out. Take him to the vet. Your vet will be able to examine the hair itself, look at skin cells under a microscope, do bloodwork, and perform a urinalysis to look for clues as to the cause.
Since some of the potential causes can be quite serious, and others potentially contagious to humans (such as ringworm), it’s worthwhile to address your concerns sooner rather than later.
How to encourage faster, healthier hair growth on your cat
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There are things we responsible cat guardians can do to improve the health of our cats’ hair coat, and to encourage growth.
Focus on nutrition
Make sure to feed a healthy cat food that is rich in protein, vitamins, minerals, and essential fatty acids. I tend to supplement my pets’ meals with Omega 3 and Omega 6 fatty acids from cold-water fish, just to be sure they’re getting enough. If you’d like to try adding fish oil to your cat’s diet, consider a supplement from VetriScience or Omegease.
Sometimes cats need a little help from their humans. Plus, grooming your cat is a great way to bond and build a relationship with her.
A deshedding glove, like this one from DELOMO works great to help remove and collect loose hairs. Plus, it’s fun!
A greyhound comb, like this stainless steel version by Paws Pamper, can help prevent matting in all cats, but especially in longhaired cats.
Use a parasite preventative
Even if your cat is an indoor-only cat, he is still at risk for parasites.
Indoor cats can become infested with fleas very easily, for example, and fleas can remain active in the winter indoors. Discuss your options with your vet, as parasite species vary from region to region, and pests have become resistant to particular treatments in certain geographies. You’ll have to treat for internal parasites as well.
This is a tough one. Humans are often quite surprised to learn about the kinds of things that are stressful to a cat, and often those things are difficult or impossible to change.
Environmental changes are stressful to cats: the addition of a new family member, the passing of a family member, moving, or even just moving the furniture. The addition of another cat or dog to the household can be very stressful, too.
A change in routine, a change of food, or a change of brand of litter, can all be stressful to a cat. Too much handling, or even too little handling, can be stressful. What’s a loving cat guardian to do?
If you can’t remove the stressful event or thing from your cat’s life, you can make his environment feel safer. Add perches and hiding places so your cat can get away from it all. Provide lots of toys, but especially enrichment toys that mimic aspects of hunting, which is an import cat behavior. Consider puzzle toys, laser pointers, and fishing-rod toys to start.
Are certain breeds more prone to shedding?
Except for hairless breeds, there are no breeds that are more or less prone to normal shedding. It’s a myth that longhaired breeds shed more than shorthaired ones.
Long hairs strewn about the carpet are probably just more noticeable than short ones.
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Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.
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 Milner, Yoram, et al. “Exogen, Shedding Phase of the Hair Growth Cycle: Characterization of a Mouse Model.” Journal of Investigative Dermatology, Elsevier, 8 Dec. 2015, https://www.sciencedirect.com/science/article/pii/S0022202X15417737.
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 “How Fast Does Cat Hair Grow?”
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 Becker, Dr. Marty. “You Can't Stop Cat Shedding, but You Can Handle the Hair.” Vetstreet, 5 July 2011, http://www.vetstreet.com/dr-marty-becker/help-cat-fur-is-overtaking-my-home.