Cat shedding: normal moulting versus real hair loss

Quick answer

Cats moult twice a year, heavily in spring and again in autumn, and they do it in response to changing day length rather than temperature. An indoor cat living under artificial light never gets a clear seasonal signal, so it sheds moderately all year with only blunted peaks.

The useful question is not how much hair you are finding. It is whether the hair is coming out at the root or breaking off, and whether the skin underneath looks normal. Those two checks separate a normal moult from every disease that imitates one.

A comb through the undercoat removes more hair in two minutes than a brush over the topcoat does in ten.

• Combing out the undercoat is what reduces shedding around the house. Brushing the surface does very little.
• Hair that snaps off leaving stubble is over-grooming or skin disease, not moulting.
• Bald patches, scabs, or skin that is red, scaly or greasy are never a normal moult.
• A cat that suddenly looks unkempt has usually stopped grooming, and that is a health sign.
• Frequent hairballs are a reason to see a vet, not a normal consequence of shedding.

Decide in 60 seconds

Why cats moult when they do

Hair does not grow continuously. Each follicle runs a cycle: an active growth phase, a short transitional phase, a resting phase, and then release of the old hair as a new one pushes up behind it.

In cats these cycles are not synchronised across the body. Neighbouring follicles are at different points, which is why a healthy cat sheds a little all the time and never develops the patchy, bald look that a synchronised moult would produce.

The pacing of the cycle is set mainly by photoperiod. Light entering the eye suppresses melatonin release, and the changing pattern of that signal through the year tells the follicles when to shift phase. Ambient temperature has much less influence than owners expect.

This is why an outdoor cat in a temperate climate produces two obvious blowouts a year, and an indoor cat under evening lamps produces a moderate, endless shed. It is also why a cat that has recently moved from an outdoor life to an indoor one may shed oddly for the first year.

The undercoat is the part that matters. The fine secondary hairs are shorter, softer, far more numerous than guard hairs, and they are what ends up on the sofa. Anything that only touches the outer coat leaves the undercoat exactly where it was.

What a normal coat looks like

Run a hand against the lie of the coat and look at the skin.

Healthy cat skin is pale and dry, with no redness, no scale, no greasy feel and no smell. The coat parts cleanly and springs back. Hairs that come away do so easily, with a soft rounded root, and there is no bald skin behind them.

Hair length and density vary enormously by breed. A Maine Coon or a Norwegian Forest cat carries a heavy double coat with a dense undercoat and will produce an alarming volume of hair in spring while being entirely healthy. A Siamese or Bengal has a short single coat and sheds far less. A Devon or Cornish Rex has almost no guard hair, and its coat is thin, wavy and easily broken. A Sphynx sheds essentially nothing but accumulates skin oil that has no hair to wick into.

Age changes the picture. Kittens carry a soft, fine coat that is replaced by adult hair over the first several months. Older cats often develop a coarser, drier coat, more dandruff and slower regrowth after clipping.

Part the coat and look at the skin. Pale, dry and unmarked is what you want to see under a heavy moult.

Shedding, or something else

This is where most owners go wrong, because the volume of hair looks the same either way. The distinction is made by examining the hair and the skin, not by measuring the pile.

Normal moult.

Hair comes away at the root when you comb. The remaining coat is even. Skin is normal. The cat is comfortable and grooming normally.

Over-grooming, also called barbering.

The hair is broken part way along its length, so the area feels like stubble or velvet rather than bare skin. It is usually symmetrical, on the belly, inner thighs, flanks or forelegs, because those are the places a cat can reach with its tongue. Cats often do this in private, so many owners believe the hair is simply falling out.

The causes of over-grooming, in rough order of how often they turn out to be responsible: flea allergy, other allergic skin disease, pain somewhere under the licked area, and finally anxiety. Bladder pain and arthritis both produce belly and hind limb licking, so a behaviour diagnosis should be the last one reached rather than the first.

Flea allergy dermatitis.

Small crusts you feel rather than see, concentrated along the spine and around the tail base. A single flea bite can drive weeks of itch in a sensitised cat, so finding no fleas does not rule it out.

Ringworm, which is a fungal infection rather than a worm.

Broken hairs with scaling, often circular, commonly on the face, ear margins, paws and along the back. It is contagious to other pets and to people, so scaly circular lesions on a household member alongside a patchy cat is a strong clue.

Parasitic mites.

Ear mites produce dark crumbly debris and violent ear scratching. Other mites cause intense itch with scale.

Hyperthyroidism.

A middle-aged or older cat that is losing weight with a good appetite, becoming restless or vocal, and whose coat is unkempt, matted or greasy despite the cat appearing to groom.

Any illness that stops the cat grooming.

Kidney disease, dental pain, arthritis and cancer all present with a coat that has simply been abandoned. The give-away is dandruff and clumping over the lower back and rump, the areas that need the most flexibility to reach.

Obesity.

Physically unable to reach the lower back and tail base. Same appearance, entirely mechanical cause.

A large synchronised shed weeks after a systemic stress.

A high fever, surgery, anaesthesia, pregnancy or severe illness can push many follicles into the resting phase at once. Weeks later they release together and the cat loses a startling amount of hair over a short period. It regrows, but the underlying event is worth identifying.

Diet.

Hair is largely protein, and coat quality suffers on a protein-poor or fat-poor diet. This shows up most often in home-prepared diets that have not been formulated, not in commercial complete foods.

The routine that actually reduces shedding

Comb first, brush second.

A fine to medium metal comb reaches the undercoat and finds mats before they set. A slicker or bristle brush finishes the topcoat and spreads oil. Doing it in the other order just pushes loose undercoat down flat.

Work in sections and in the direction of the coat.

Small strokes, one area at a time, with the other hand flat on the skin so you can feel resistance before the cat does.

Frequency by coat type.

Short single coats do well with a comb through once or twice a week. Dense double coats and long coats need combing most days during a moult and several times a week the rest of the year. Rex coats need a soft brush or a rubber grooming glove only, and no de-shedding blade at all.

Keep sessions short and stop early.

Two minutes ending while the cat is still relaxed builds a routine that lasts years. One long session that ends in a struggle teaches the cat that grooming is something to escape.

Check as you go.

Grooming is the best whole-body examination an owner ever performs. Feel for lumps, scabs, sore spots, ticks, mats behind the ears and in the armpits, and matted hair under the tail.

Watch the areas the cat cannot reach.

The centre of the back, the rump and the base of the tail. Problems appear there first in seniors, in overweight cats and in arthritic cats.

A comb, a soft brush and a towel are enough. De-shedding blades cut guard hairs and are the wrong tool for thin or Rex coats.

Hairballs are a symptom, not a season

A cat swallows a large amount of hair simply by grooming normally, and that hair usually passes through the digestive tract without incident.

A hairball forms when hair accumulates in the stomach faster than it moves on. That happens for two reasons: the cat is swallowing more hair than usual, or the gut is not moving it along as it should.

More hair usually means over-grooming, which brings you back to the differential list above. Slower transit points to gastrointestinal disease, and inflammatory bowel disease and intestinal lymphoma both present in exactly this way in older cats.

So a cat that brings up a hairball occasionally during a heavy moult is unremarkable, and a cat that does it regularly, or that retches without producing anything, needs to be examined rather than given a lubricant paste.

Retching that produces nothing at all, repeated over hours, is not a hairball problem and should be treated as urgent, because it can also be how an obstruction or a chest problem looks.

Where the popular advice fails

"Shave the cat in summer."

The coat insulates in both directions and it protects skin from sunburn, which matters especially for white cats and pale ears. Shaving a healthy cat for heat is unnecessary, and some cats regrow the coat poorly afterwards. Clipping is a treatment for severe matting, not a seasonal routine.

"Use a de-shedding blade, it takes out the most hair."

Those tools work by cutting hair that catches in a fine blade. Used often or with pressure they thin guard hairs, scrape skin and leave a patchy coat, and on a Rex or a thin-coated cat they cause real damage. A comb removes shed undercoat without cutting anything.

"Bathe the cat to reduce shedding."

Most cats do not need bathing. Detergent strips coat oils, the process is stressful, and the wet cat then over-grooms itself dry, swallowing more hair. Bathing has a place in ringworm treatment, in heavy soiling and in some skin disease, on veterinary advice.

"Add oil to the food for the coat."

A supplement will not fix a coat that looks bad because of thyroid disease, kidney disease, parasites or pain, and it delays the diagnosis. Fix the cause, then consider whether the diet needs adjusting.

"Hairball paste solves hairballs."

Lubricants may help a cat pass hair, but a cat producing frequent hairballs has a reason, and paste is a way of not finding it.

What never to do

Do not use scissors anywhere near a mat.

Do not use human shampoo, which has the wrong pH for cat skin.

Do not use a dog flea product on a cat. Several contain permethrin, which is severely toxic to cats and causes tremors and seizures.

Do not pull a mat apart in one go. Work at the outer edge, split it into strands, and stop before the cat does.

Do not restrain a cat firmly for grooming. Short sessions with the cat free to leave produce a cat that tolerates grooming for life.

Do not assume an indoor cat cannot have fleas or ringworm. Both arrive on shoes, on other pets and on visitors.

When to get help

Book a veterinary appointment for any bald patch, any broken-hair pattern, any scabs, scaling or redness, and for a coat that has become greasy, clumped or matted when it never used to be.

Go sooner if the cat is losing weight, drinking more, vomiting repeatedly, or if anyone in the household has developed circular scaly skin lesions.

Bring photographs of the pattern taken in good light, the name and date of the last flea and parasite treatment for every animal in the home, the current diet, a weight history, and a note of whether the hair is broken or shed at the root. That last detail changes the whole line of investigation and almost no owner arrives with it.

Short, frequent sessions that end while the cat is still calm are what make grooming sustainable for the next fifteen years.