Why Does My Cat Have Dandruff? 

Structure of the Skin 

The skin is the biggest organ of the body (one to remember for pub quiz night!) and has a variety of functions, ranging from protecting deeper tissue from damage (thermal, chemical, physical and microbial), to regulating body temperature, to excreting waste products via sweat, to interacting with the world via sensation, to storage and more. Healthy skin is essential to keep an animal healthy. 

The skin is made up of multiple layers. The deepest is the hypodermis/subcutis – this is made up mainly of fat. Next is the dermis, made up of connective tissue, which gives the skin structure and strength. Above this is a layer of basal cells – these cells divide to produce layers of skin cells. As new cells grow underneath, old skin cells are pushed to the surface, becoming thinner, until they break off and leave the skin as squames. These are often microscopic though can be visible as skin flakes. This regeneration is normal, but high numbers of skin flakes can indicate disease.  

Dotted throughout the layers of skin are sweat and oil glands, nerve endings, tiny muscles, blood and lymphatic vessels, immune cells and hair follicles. 

Effects of Dry Skin 

Far from being benign, dry skin in cats can lead to several issues so should not be ignored. Dry skin causes pruritus (itchiness), which causes a cat to scratch their skin. This creates inflammation and pain that encourages further pruritus. The skin can become broken and damaged, which can open the skin up to infection.  

Causes of Dry Skin 

There are many causes of dry skin in cats; let’s look at some of the more common now: 

Parasites 

Parasites are the first thing you should think of if your cat has dry skin. Here are the parasites you might need to know about. 

Fleas are little blood-sucking parasites that live on your cat’s skin, and lay eggs in the house. They also feed off humans, so should be dealt with quickly, especially as they rarely can transmit disease such as tapeworms (and the plague!). Fleas cause your cat to scratch mainly their tail base, face and legs, though they can scratch all over. This causes dry and damaged skin. Fleas can be seen as tiny black insects that jump in their fur, and the black/red faeces they leave behind. Treatment involves anti-parasitic drugs (tablets are generally recommended where possible to minimise environmental contamination), as well as treating the environment with flea spray, regular hoovering and hot washing soft furnishings. 

Mites are less common than fleas but can also cause irritation and dry skin. Cheyletiella live in the fur and, like fleas, cause irritation on the tail base and can also infect humans. Otodectes, the ear mite, lives in and around the ears of cats which can cause itchy, dirty ears and ear infections. Demodex is a mite that lives on a normal cat’s skin in low numbers and rarely causes disease – however, if there is underlying skin or immune-system disease, Demodex can cause itching and dry skin. Mites can be diagnosed by a vet via hair and skin sampling. All these mites can be treated with anti-parasitic drugs, and may require environmental treatment too.  

Check your pets symptoms

Symptom Checker

Finally, ticks are little arachnids that burrow into a cat’s skin to feed on blood. Individually, they can cause mild irritation and itching that can lead to dry skin, but the larger concern is the spread of tick-borne diseases like Lyme disease (which can cause joint and kidney disease), Anaplasma (which damages red blood cells and platelets), and Bartonella henselae (which rarely causes symptoms in cats but can cause cat scratch fever in humans). Ticks are prevalent in certain areas of the country, so if you live in a tick-hotspot, always check your cat’s fur thoroughly when they come in from outside. An appropriate anti-parasiticide will protect your cat from tick-bites and their associated diseases.  

Environmental Factors 

Decreased humidity, such as during winter, can increase the risk of dry skin developing in cats. Though most healthy cats can manage, and many homes have decent climate control, older, skinner or unwell cats may be more vulnerable to their skin drying out. Check your cat’s skin regularly in harsher weather. 

Similarly, cats with a poor diet might be at risk of dry skin, particularly one low in oils. Most complete cat foods have balanced nutrients that promote healthy skin, but if your cat is fed an inappropriate diet they may be more vulnerable to dry skin. Always ensure your cat is a fed a complete balanced diet with plenty of water.  

Finally, stress can be a factor in causing dry skin. Cats are creatures of habit, and small changes can cause big upset. This might be a new person in the house or another leaving, another cat outside causing them stress, building work at home or a change in routine. It is not uncommon for cats that are stressed to overgroom or scratch themselves excessively, which can cause dry and damaged skin. You can minimise stress by keeping routines the same, providing a place for your cat to hide and destress, using pheromone diffusers, or veterinary anxiolytic drugs.  

Pyoderma  

Pyoderma is bacterial skin infection. Bacteria live on your cat’s skin in normal amounts and provide benefits like protecting against pathogenic organisms. However, pyoderma can develop if these bacteria become aggressive and pathogenic, or if other bacteria colonise the skin. It is rare for pyoderma to be the primary problem and is usually associated with another disease (such as parasites or allergies) – when a cat scratches, the skin is damaged, allowing bacteria to enter the wound and cause infection. 

Skin infections can be hot, red and painful, may ooze pus, and can even spread deeper into skin and around the body. Dry skin can be an early warning sign of pyoderma developing. Pyoderma can be diagnosed visually, via microscopy of samples of skin, and growing the bacteria from these samples. Treatment may involve antiseptic washes, topical or oral antibiotics and pain relief. Treatment of the primary problem is also essential.  

Ringworm  

Ringworm, or dermatophytosis, is not any kind of worm but a fungal skin disease. As with pyoderma, ringworm can infect skin that is damaged or has a weakened immune system, so is often secondary to a primary disease. It causes dry crusty skin, that can be irritating and cause hair-loss. It gets its name from the ring-like marks it can leave in hair. However, infection in cats can also be asymptomatic – it more commonly causes disease in old, young or immunocompromised cats.  

Ringworm can be diagnosed in cats via a special lamp that causes some ringworm species to glow, hair and skin samples, and culturing the skin. Treatment may not be needed, as it can be self-limiting, but more severe cases may require topical or oral anti-fungal drugs. Cleaning the environment is essential to prevent reinfection. Ringworm can also infect humans from cats, so any cat with suspected ringworm should be treated with caution, and vulnerable people should not come into contact with the cat or their bedding.  

Allergies 

An allergy is an exaggerated reaction by the immune system to a generally harmless trigger (allergen). Allergens can be anything environmental like pollen, flea saliva, dust mites, grass or chemicals, or food such as animal proteins or, less commonly, plant ones. Food-allergies can also cause chronic diarrhoea, weight loss or lack of weight gain, and vomiting.  

An allergic response can be instant or take hours or even days to develop. They cause irritation, itching and discomfort, which can lead to scratching and overgrooming. This breaks the skin which can allow secondary bacterial or fungal infections. Most allergies develop from around 6-months old to 3-years old. Purebred cats may be more predisposed but any cat can develop an allergy. Flea allergies are very common, meaning even if a cat is well-protected against fleas with their anti-parasitic medication they can become itchy from a single bite. This often presents as damage to the head, neck and chin. 

Allergies can be difficult to control. There are non-specific anti-allergy and specific immunotherapy drugs that can control the symptoms. Topical treatment is always recommended to keep a cat’s skin from getting dry. Certain diets and supplements will also help maintain a healthy skin barrier. Unfortunately, treatment of allergies is rare and most cats will require long-term control to prevent flare-ups.  

Hormonal, Autoimmune and Neoplastic Disease 

There are rarer diseases that can cause dry skin in cats.  

Hormonal disease, such as diabetes mellitus and hyperthyroidism, do not directly cause dry skin, but they can lead to dehydration that can dry the skin out. Other causes of dehydration, such as renal disease, vomiting and diarrhoea, and heatstroke can cause dry skin too. The skin will also be less elastic and the fur poor quality. These diseases often have other signs you should look out for, such as weight loss, drinking and urinating more, eating changes and vomiting or diarrhoea. 

As well as causing allergies, the immune-system can affect cat’s skin in other ways. Pemphigus is an auto-immune condition that causes primarily crusting and blistering skin around the head, paws and claws. It is usually more serious than simple dry skin. It may require biopsies to diagnose and usually requires a long course of immunosuppressants to treat. A similar disease called plasma cell pododermatitis only affects the pads of cats and presents as dry puffy pads – it can progress, however, to large ulcerated swollen paws. Again, treatment with immunosuppressive drugs is usually affective.  

Finally, there are certain cancers of the skin in cats that can initially present as quite benign growths, with dry skin as a feature. Squamous cell carcinomas may develop primarily on lighter areas of skin, such as the ears and nose, and the risk can be increased by exposure to sunlight. Lymphoma in cats often occurs within the gastrointestinal tract causing diarrhoea, but can also present as skin lesions, including scaley dry skin, pruritus and ulceration. Unfortunately both cancers are quite serious and quickly spread to other parts of the body. They can be diagnosed via cytology or biopsy, and may be treated with surgery, radiotherapy or chemotherapy.  

The bottom line… 

Dandruff might just be “your cat”. But it can also be a sign of more serious underlying health conditions, that really do need checking out!