Cat Hair Loss and Bald Patches: Itching, Allergy or Hormones

Hair on the sofa, on your clothes and in the corners comes with owning a cat. It becomes a sign in one case only: when the cat itself develops areas where the coat is visibly thinner or gone. From that point the question stops being about how much fur is in the flat and starts being about skin, itching and metabolism.

Why a Cat Loses Hair: Falling Out or Being Chewed Off

This is the first fork, and it decides everything after it. True hair loss means the hair leaves the follicle whole: skin is bare, the coat lifts away between your fingers, and the bald area is smooth. That happens with hormonal disease, ringworm, injection reactions and severe illness.

The second and far commoner situation is a cat that chews and licks the hair off itself. Owners almost never witness it: cats groom when nobody is handling them, often at night, and they do it silently. The owner is convinced the hair is falling out, while what they are looking at is the work of a tongue. If the picture is unclear, describe all of it — that is what the cat symptoms page is for.

How to Tell: Look at the Hair, Not the Skin

• Run a finger against the coat at the edge of the bare area. True loss feels like bare skin; overgrooming feels like bristle — broken hairs all of the same length.
• Look at the hair tips. A blunt, even end means the hair was broken by teeth, not shed.
• Read the pattern. Overgrooming leaves bald patches where the tongue reaches: belly, inner thighs, groin, forelegs, flanks. True loss more often runs along the back, behind the ears, around the eyes, or in scattered spots.
• Check the skin. Redness, crusts, scratches and flea dirt mean inflammation; smooth pale skin with no changes points at metabolism.

Itching: Fleas, Allergy and Parasites

If the cat is grooming itself bare, look for itching, and itching starts with fleas. In flea-saliva allergy a single bite can keep a cat licking for weeks, and you may never find a flea: the cat combs them out with its tongue. That is why every animal in the household is treated, even when nobody has seen one.

Next in frequency: allergy to a food component, atopy (pollen, dust, house-dust mites), mites, and ringworm. Food intolerance is confirmed only by a strict elimination diet run for six to eight weeks — how that is built is covered in gastritis and food allergy and therapeutic pet food; the baseline diet choice is in choosing food for a cat. If scratching rather than licking leads the picture, it is covered separately in a cat scratching.

A word on ringworm: it gives round scaly bald areas, most often on the face, ears and paws, with only moderate itching, and it is catching for people. It is diagnosed by culture or PCR, not by a Wood's lamp, which fluoresces in only some cases.

Overgrooming from Stress and from Pain

Cats groom to calm themselves, and under chronic stress that turns into a habit: a move, building work, a new pet, a territorial conflict, boredom indoors. The classic picture is a symmetrical bald belly and inner thighs over perfectly healthy skin.

But before calling it nerves, pain is ruled out: a cat licks the place that hurts. The belly with bladder inflammation, see blood in cat urine; the lower back and rump with sore joints, see cat limping; a single leg after an injury. Psychogenic alopecia is a diagnosis of exclusion and is made far less often than owners assume.

Bald Patches and Hormones

Hormones cause less coat disease in cats than in dogs, but they still get checked. What points to them is a combination: hair thinning symmetrically, thin skin, almost no itching, together with a change in general condition. Landmarks:

• hyperthyroidism — an unkempt, matted coat while the cat eats a lot and loses weight, see a cat losing weight;
• diabetes and cortisol excess — thirst, a wet tray, thin skin, a pendulous belly, see a cat drinking a lot;
• severe chronic disease of any organ — the coat dulls and thins because the body has other priorities, and the cat is dull with it, see a lethargic cat.

Seasonal Moult: What Counts as Normal

Normal looks like this: the coat thins evenly over the whole body, there are no bald patches, the skin is clean and unreddened, the cat is not grooming more than usual, and nothing else has changed. Indoor cats under constant artificial light moult all year round, so "sheds year-round" is normal too, not a disease.

During a moult a cat swallows more hair, which can end in hairball vomiting — a separate story covered in vomiting and diarrhoea in cats. Brushing and enough moisture in the diet help; random "hairball tablets" do not.

When to See a Vet Urgently

• bald areas spreading within days, with weeping skin, crusts or ulcers;
• the cat has licked the skin raw and will not let you touch it;
• hair loss together with weight loss, thirst, dullness or fever;
• round scaly bald patches, especially if people in the household develop itchy skin lesions;
• swelling, discharge or a bad smell from the affected area.

Otherwise an appointment within the week is right. If you are unsure how urgent it is, describe it in plain words and get an urgency read from the symptom review.

What Not to Do at Home

• Do not give human medicines or creams. Human painkillers and fever medicines are lethal to cats, and a steroid cream will simply be licked off. All medication is prescribed by a veterinarian only.
• Do not use flea products made for dogs. Some of them kill cats; the treatment is chosen by a vet for the species and weight.
• Do not shave or clip the bare area before the exam: you destroy the main piece of evidence, which is the state of the hair tips.
• Do not apply spirit, dyes or oils: they irritate the skin and make scrapings and cultures unreadable.
• Do not change the food in the week before the appointment, and do not start an elimination diet without a vet: an unfinished diet answers nothing and the time is gone.

What Tests Will Clarify the Picture

The dermatology minimum is done in the consulting room and settles most cases: a flea comb, skin scrapings for mites, trichoscopy (broken hair tips under the microscope answer the falling-out-or-chewed question immediately), skin cytology, and culture or PCR for ringworm.

Blood is needed when systemic signs are present: a complete blood count and biochemistry, thyroid hormones in cats over seven, and glucose plus urine if there is thirst. What the numbers mean is explained in cat blood test, and a completed form can be uploaded for pet results interpretation in plain language. When a hormonal cause or a mass is suspected, the internal organs are imaged: cat abdominal ultrasound; a clinic report is read through pet imaging interpretation.

This article is informational. Diagnosis and treatment of your pet are the job of a veterinarian.