A louse is an insect, rather than a mite. Cat and dog chewing lice are different species, and feline lice infestation does not mean human head lice. Identifying the parasite helps select treatment and distinguish infestation from other causes of itching.
When to see a vet urgently
Contact a vet promptly in the following situations:
- Your cat has extensive broken skin, discharge or marked tenderness.
- A kitten is not eating, loses weight or becomes clearly weak.
- Your cat's mucous membranes are pale or general health deteriorates.
- Drooling, tremors, unsteadiness or seizures occur after a parasite treatment.
Exposure to a dog parasite treatment requires immediate contact, even without symptoms. You can find a vet near you.
Overview
Chewing lice are small, yellowish insects about 2 mm long that live in a cat's coat and attach their eggs, called nits, to hairs. Their entire life cycle takes place on the animal, so infestation continues until treatment starts. Lice are more common in cats with outdoor access, shelter cats and those with weakened immune systems.
Females attach eggs firmly to the hair surface. Ordinary washing may therefore not remove them. The immature stage that hatches from an egg resembles a small adult louse. Cleaning the coat surface alone does not always interrupt every stage of development.
Unlike fleas, lice live mainly on the animal throughout their development. Lice that leave their host do not usually survive long. Addressing infestation in contact cats is therefore central, although cleaning bedding and brushes is also part of treatment.
Causes
The main sources of infestation are:
- Direct contact with affected animals.
- Shared care items, such as beds and brushes.
- Time spent in shelters, kitten farms or outdoors.
- Transmission from a mother cat to her kittens.
Dirt alone does not create infestation: a parasite and an opportunity for transmission must be present. Being in a shelter or outdoors describes possible contacts, rather than certain infestation. An indoor cat can also be exposed through a new cat or shared grooming equipment.
Chewing lice are host-specific. Treatment for a parasite found on a person or dog cannot be inferred from the finding in a cat. If several animals have itching or specks attached to their hairs, tell your vet all their species and contacts.
Risk factors
Lice are more common in cats that:
- Do not receive regular parasite treatment.
- Spend time outdoors or in shelters.
- Have reduced immunity or chronic disease.
- Are older or in poor condition.
- Have thick, long coats.
Heavy infestations occur particularly in older, ill or poorly conditioned cats. A long coat can make both grooming and spotting parasites harder. Some older cats can no longer groom normally. However, long hair alone does not establish infestation or reduced immunity.
The value of regular parasite treatment depends on the product: not every medicine for internal or external parasites works against lice. The need for treatment and product suitability are assessed according to your cat's situation. Finding lice alone does not prove that you have neglected your cat's care.
Main symptoms
Lice infestation can cause:
- Intense itching and constant scratching.
- Restlessness and disturbed sleep.
- Hair loss, particularly around the neck, back and abdomen.
- A dry, brittle coat.
- Nits, or eggs, on hairs, appearing as small white specks resembling dandruff.
- Scratching injuries and crusts.
- Secondary skin infections in severe cases.
Itching varies, and not every cat has severe symptoms immediately. You may first notice a poorer coat, matting or small eggs attached to hairs. Excessive licking and biting can also break hairs, so hair loss does not always look like a continuous bald patch.
Nits remain attached more firmly than ordinary loose dandruff. However, a small pale speck alone does not confirm the diagnosis. Magnification allows your vet to distinguish an egg, other material attached to a hair and the insect itself. Examine the coat in sections, but do not scrape painful skin or pull apart mats.
Complications and consequences
Without treatment, infestation can lead to:
- Chronic dermatitis.
- Baldness.
- Secondary bacterial and fungal infections.
- Marked weight loss in weakened kittens; chewing lice do not suck blood and therefore do not cause anaemia.
The cat chewing louse is not a blood-sucking parasite. If your cat is pale or anaemia is suspected, the cause is investigated separately rather than automatically attributed to lice. A kitten's weight loss or poor condition may also require broader investigation than simply removing parasites.
Scratching can break the skin and predispose it to bacterial infection. However, fungal infection is not a usual or inevitable consequence of every lice infestation. Ringworm, for example, can itself cause coat and skin changes and requires its own investigations. Itching or hair loss can result from several concurrent problems.
Diagnosis at the vet
To detect lice, the following are used:
- Examination of the coat and skin to find insects and nits.
- Microscopic examination of coat brushings.
- Distinguishing lice from fleas and mites.
What is examined in the coat?
Lice and eggs are sought by parting the coat in good light and combing where needed. The parasite's structure is examined in the sample, because identifying a flea or mite, for example, leads to a different treatment plan. A few eggs or a moving insect may be enough to demonstrate infestation; a blood test is not needed solely to identify a louse.
When are further investigations needed?
Your vet also assesses skin damage and general condition. Cytology of a skin sample can help assess bacterial or yeast infection. A scraping may be taken if mites are suspected, while suspected ringworm may require hair examination or fungal sampling. Blood tests are considered for weight loss or other general symptoms, for example.
Report when symptoms began, whether new animals have joined the home and which parasite products have been used. Bring the packaging details. If itching continues despite treatment, the vet assesses how treatment was carried out, re-exposure and other skin diseases.
Treating lice infestation
Treatment uses a product suitable for cats that is effective against lice. Age, weight, health and the product's conditions of use are considered. Being a spot-on, tablet or collar alone does not establish effectiveness or safety. Your vet also plans monitoring and any repeat treatment.
Eggs and contact cats are considered
Because of the egg stage, a single application does not resolve the whole infestation with every product. Follow the instructions for the chosen product; do not repeat treatment early or combine substances yourself. Treatment of contact cats is coordinated to prevent the infestation cycling back.
Combing can complement treatment, but does not replace an effective parasite medicine. A professional can help tidy a heavily matted coat. Inflamed or ulcerated skin is treated separately. Antibiotics or antifungals are not automatically started for every cat carrying lice.
Do not use a dog product on a cat
Some dog products containing permethrin are particularly dangerous to cats. Even a small part of a dog's pipette is not a safe way to adapt a product for a cat. Exposure can also occur through licking or close contact with a recently treated dog.
Read the species, conditions of use and warnings on the packaging. Do not apply an environmental treatment spray to a cat. If the wrong product has been used, contact a vet immediately and keep the packaging available. Tremors, drooling and seizures may be signs of poisoning.
Home care and monitoring
Wash beds and clean brushes, combs and other shared equipment according to treatment instructions. Collect loose parasites and hairs removed during handling. Lice do not automatically require the same extensive environmental control as a severe flea infestation. The key is to treat infestation on the animal and prevent renewed contact with an untreated carrier.
Monitor skin healing, itching and coat condition. Symptom improvement alone does not show that every developmental stage has disappeared. Conversely, a poor coat does not recover immediately after parasites are removed. If live lice remain visible or the skin worsens, your vet checks the treatment outcome before selecting another product.
Prevention
To prevent lice infestation, the following are recommended:
- Regular parasite treatment using spot-ons, tablets or collars.
- Treating all household animals at the same time.
- Disinfecting beds, furniture and grooming equipment.
- Managing contact with outdoor and stray animals.
- Regular preventive veterinary examinations.
Treating all household animals means a plan appropriate to each species and confirmed risk, rather than giving everyone the same substance. People are not treated with head lice products because a cat has chewing lice. Any parasite infestation in a dog or other pet is investigated separately where necessary.
Washing and mechanical cleaning particularly target shared textiles and grooming equipment. Strong disinfectants do not replace treatment of the animal. Check a new cat's coat and skin before close contact with others, and report obvious itching or parasites promptly.
What it means for owners
Although lice are less common than fleas, they cause intense itching and coat problems. Remember that preventive treatment protects your pet against lice and other dangerous external parasites.
Frequently asked questions
Can cat lice spread to people?
The cat chewing louse is host-specific and does not live on people like human head lice. People are not treated with head lice products because of a cat's infestation. Any skin symptoms in a person are assessed separately where needed.
How can I distinguish a louse egg from dandruff?
An egg is firmly attached to a hair, whereas loose dandruff comes off more easily. However, a pale speck alone is not enough for identification; your vet can examine a sample under magnification.
Is washing my cat enough?
Ordinary washing does not reliably remove attached eggs or resolve infestation. Your cat needs a suitable treatment effective against lice, with contact cats also considered.
Can I give a cat a small amount of dog parasite treatment?
No. Some dog products can cause serious poisoning in cats even in small amounts. Use only a product intended for cats and suitable for your cat's situation.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Lice of Cats, Merck Veterinary Manual, accessed 2026-11-03.
- Lice, Companion Animal Parasite Council, accessed 2026-11-03.
- Control of Ectoparasites in Dogs and Cats, European Scientific Counsel Companion Animal Parasites, accessed 2026-11-03.
- Diagnosis of Skin Diseases in Small Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Permethrin toxicity in cats, PDSA, accessed 2026-11-03.
- Permethrin: don’t put your cat at risk, Veterinary Medicines Directorate, accessed 2026-11-03.
- Guideline for Dermatophytosis in Cats, ABCD, accessed 2026-11-03.
- Ectoparasites - Insects, European Scientific Counsel Companion Animal Parasites, accessed 2026-11-03.
- Initial Triage and Resuscitation of Small Animal Emergency Patients, Merck Veterinary Manual, accessed 2026-11-03.
