How to Identify Skin Diseases in Cats: Symptoms, Causes, Treatments, and When to See a Vet, Explained by a Veterinarian

Have you been checking your cat's skin? Signs such as "licking the same spot," "hair loss," or "having bumps" are often symptoms of skin disease. Many cat owners are unsure about when they should take their cat to a veterinary clinic. In this article, we will explain everything from the causes of skin diseases to the guidelines for when to seek veterinary care.

What is feline skin disease?

When a cat develops a skin disease, symptoms such as "itching," "redness," and "hair loss" usually appear, but the causes are varied. You cannot determine the cause of dermatitis based on symptoms alone.

Infectious diseases

Bacterial and fungal infections cause dermatitis accompanied by inflammation. This can cause itching and eczema. Even healthy skin has resident bacteria and fungi, which usually do not cause harm. However, if itching occurs for any reason, these resident skin organisms can overgrow and lead to secondary bacterial dermatitis.

Fungal dermatitis is characterized by circular hair loss. The main cause is a fungus called dermatophyte, but other types of fungi can also cause dermatitis. It can infect soft skin areas (paws, arms, face, etc.), and the hairless area becomes inflamed and surrounded by redness. This dermatitis is also known as ringworm. It can be transmitted to other cats and even humans. One type of resident skin fungus is a yeast called Malassezia. It thrives on oily skin, and when it overgrows, it is accompanied by a unique fermented odor and itching.

Parasites

External parasites such as fleas and mites can cause dermatitis. Fleas and mites infest a cat's skin. The cat may have an allergic reaction to the saliva or excrement of these parasites, leading to dermatitis. Features include intense itching, eczema, and hair loss.

Allergies

Allergies can be triggered by food, dishes, or external parasites. Redness and eczema occur where the skin comes into contact with the allergen. Since the itching persists until the causative substance is removed, the cat may scratch the skin raw, leading to a secondary infection by bacteria or other pathogens.

Stress or pain

Cats may scratch or lick their entire body due to stress. They are not licking because of itchiness; they are scratching or licking due to discomfort or pain, which causes hair loss. In severe cases, the cat may scratch or lick until the skin is raw, leading to sores or a wet, oozing state due to secondary infections like bacteria. Skin inflammation due to stress occurs only in the specific areas that the cat continues to lick.

Hormonal imbalances

Diseases of the adrenal glands or thyroid, which secrete hormones, can impair the skin's barrier function and cause skin diseases. Diabetes is also a disease involving hormonal imbalance that can sometimes lead to dermatitis. Eczema may appear all over the body.

Autoimmune diseases

Autoimmune diseases occur when the immune system attacks the body's own cells. Autoimmune diseases that cause feline skin lesions include pemphigus and lupus erythematosus. Crusts, redness, and hair loss may occur on the face, ears, and paw skin.

Tumors

Tumors such as cutaneous mast cell tumors in cats also cause skin lesions. They create small wart-like lumps, and the itchy substances released by the tumor trigger itching. Redness may also appear around the hair loss or the mass. Additionally, squamous cell carcinoma is a tumor that can develop on the skin, causing lumps and ulcers. In cases involving the ears or early-stage lesions, the lumps and ulcers are small, which can make them appear similar to other skin diseases.

How to identify feline skin disease | Watch out for these symptoms

Cat licks its body frequently

Cats lick themselves to keep their skin clean (grooming). Therefore, grooming is normal behavior. However, excessive grooming occurs when they lick until hair loss or skin redness appears, or if they keep licking the same part of their body. While some cats lick due to itching, it can also develop into excessive grooming due to stress or pain.

Because a cat's tongue is rough, constant licking strips away the surface of the skin. This can lead to bacterial infections, resulting in raw, oozing sores.

Cat scratches/seems itchy

Many skin diseases cause itching. In particular, allergies, flea/mite infestations, and bacterial or fungal infections can cause intense itching. Also, even if the itching is mild at first, scratching can cause an infection that intensifies the sensation.

Hair loss/alopecia

Hair loss occurs in many skin diseases.

If a cat is licking an area due to itching, discomfort, or pain, hair loss will occur only in the area being licked. If hair loss is caused by excessive licking, you might see broken hair shafts.

Circular hair loss is commonly seen in dermatitis, but it is also characteristic of dermatophytosis, which is a fungal infection.

Hormonal diseases can cause symmetrical hair loss, although it is often absent. Allergic dermatitis can also cause symmetrical hair loss.

Skin is red/has eczema

Skin redness and eczema are common signs of skin infection. If the skin is itchy, the cat may lick it, or inflammation may occur, causing the skin to turn red. Bacterial infections in the hair follicles cause eczema. Scratching it raw can lead to widespread inflammation.

Has scabs

Scabs (crusts) form when the skin is raw, causing body fluid (exudate) to seep out. When this fluid dries, a scab is formed.

Scabs can be caused by scratching, allergies, flea/mite infestations, or pathogen infections, although it may just start as eczema. Scabs can also be seen in autoimmune diseases like pemphigus.

Attempting to force a scab off will damage normal skin and worsen the inflammation, so wait until it falls off naturally.

Increased dander

New cells are constantly being produced in the skin. There are layers of cells in the stratum corneum (the skin's surface layer), and the cells produced in the bottom layer (basal layer) are gradually pushed up to the surface. It takes 21 days for them to flake off (turnover), and these shed cells appear as dander.

While normal skin cells take 21 days to shed, dryness, infection, or hormonal imbalance can speed up the skin's turnover, resulting in an increase in dander.

Skin is sticky/smells

There are cells in the skin that secrete sebum. A resident yeast fungus called Malassezia thrives on this sebum. When inflammation leads to increased sebum production, Malassezia can multiply abnormally, leading to a vicious cycle of even higher sebum production. When Malassezia overgrows, it releases a distinct fermented odor. In cases of bacterial infection, it may even smell sour. Since normal skin has almost no odor, a foul odor could indicate a skin disease.

Skin is swollen/has a lump

Skin swelling or lumps may not just be inflammation; they could be tumors. It is impossible to identify the cause of skin swelling or lumps by appearance alone. To determine the cause, it is necessary to perform a needle biopsy or surgical excision for testing. Many people wait because the lump isn't growing, only to find it has spread throughout the body. Be sure to consult a veterinarian.

Main causes of feline skin disease

Infectious diseases

Bacteria and fungi are the main causes of skin infections. Particularly common are dermatitis caused by resident skin bacteria (Staphylococcus aureus, Malassezia) and dermatophytosis, which is a fungal infection. Skin disease caused by resident bacteria is not caused by the bacteria themselves initially; rather, the resident bacteria overgrow due to a decline in skin barrier function or constant scratching. This type usually is not contagious to other animals.

Dermatophytosis is a fungal infection that causes skin disease accompanied by circular hair loss. It is characterized by intense itching and ring-shaped redness around the hairless area. Because dermatophytosis can be transmitted to other cats and humans, measures such as isolation and disinfection are necessary.

External parasites like fleas and mites

A skin disease often seen in cats that go outdoors is caused by external parasites such as fleas and mites. If your cat goes outside, there is a high probability of infestation if they are not on preventive medication.

Fleas and mites attach to the skin to feed on blood. During this process, they cause an allergic reaction to proteins in their saliva, which leads to intense itching and dermatitis. Eczema develops where the skin was bitten, but it can spread over the entire body. Itching may lead the cat to scratch itself raw, worsening the skin disease.

Feline scabies is a skin disease caused by the Sarcoptes scabiei mite, which burrows into the skin to live. It excretes waste and lays eggs within these tunnels, causing an allergic reaction that triggers severe itching. The skin becomes thickened and leathery, with copious amounts of dander. While it primarily infests the head and ears, symptoms can appear anywhere on the body. Scabs may form, and widespread hair loss may occur. Feline scabies can also be transmitted to humans, so caution is required.

Allergic dermatitis

Feline allergic dermatitis includes food allergies, environmental allergies, and contact allergies. Exposure to specific allergens triggers inflammation, which occurs at the site of contact. Food allergies manifest as dermatitis on the face, ears, paw tips, and around the anus. Contact dermatitis occurs when there is an allergic reaction to metal in food bowls or collars, causing itching, eczema, and hair loss in the affected areas. Environmental allergies are triggered by house dust, mites, or pollen. This condition appears in young cats under 3 years old and worsens during seasons when allergens are abundant. Environmental allergies are also referred to as atopic dermatitis.

Stress/Psychogenic

Mental factors like stress can lead to excessive grooming, where the cat licks itself incessantly. Damaging the skin through excessive grooming allows bacteria and other pathogens to infect the area, progressing into skin disease.

While it may look like the cat is licking frequently due to a skin disease, it is sometimes actually related to stress.

Hormonal diseases

Hormonal diseases like thyroid disease, adrenal disorders, or diabetes can cause hair loss, eczema, and itching. Hormonal diseases can also present with symmetrical hair loss or a change in hair quality. Additionally, symptoms unrelated to the skin, such as increased thirst/urination, increased appetite, weight loss, or vomiting, may appear.

Autoimmune diseases

Autoimmune diseases such as pemphigus and lupus erythematosus occur when the body's own immune system attacks skin cells. Symptoms primarily appear on the face, ears, and claws, though lesions can also appear all over the body. Blisters, scabs, and skin erosions occur, along with symptoms like fever and loss of vitality.

Tumors

Some feline skin diseases are caused by tumors. For example, squamous cell carcinoma, mast cell tumors, fibrosarcoma, and cutaneous lymphoma are the main types of tumors that can develop in the skin.

Squamous cell carcinoma, mast cell tumors, and fibrosarcomas manifest as lumps, but in the early stages, these lumps may be small or look similar to other skin diseases. Furthermore, cutaneous lymphoma manifests as skin itching, redness, and dander, and as it progresses, it forms ulcers.

Skin disease caused by tumors is often indistinguishable from other skin diseases and cannot be diagnosed without performing a biopsy.

Other causes

Nutrient deficiencies due to homemade diets or poor diet quality can cause symptoms like excessive dander. Additionally, if the immune system is suppressed by the use of immunosuppressants or steroids, infections by resident bacteria can occur, leading to dermatitis.

Is feline skin disease contagious? Be aware of transmission to humans and other cats

Skin diseases that can be transmitted to humans

Among feline skin diseases, fungi, fleas/mites, and scabies are transmissible to humans. In particular, individuals with weakened immunity—such as children, the elderly, those with underlying diseases like cancer or diabetes, or those receiving medical treatment—are easily infected.

Skin diseases that can be transmitted to other cats

Just like with humans, fungi, fleas/mites, and scabies can be transmitted to other cats. Kittens, senior cats, or those with weakened immunity—due to diseases like cancer or diabetes, or medical treatments—are easily infected.

Additionally, while there are preventive medications for fleas and mites, if you do not provide them, there is a risk of external parasites.

In households with multiple cats, opportunities for transmission increase, so if the affected cat is not isolated, infection will spread rapidly.

Countermeasures if infection is suspected

If an infection is suspected, first take the cat to a veterinary clinic and the human to a dermatologist. Not all skin diseases are contagious; fleas/mites, scabies, and fungi are the main ones mentioned above. First, you need a diagnosis of whether it is contagious.

Fleas, mites, and fungi are not only spread by direct contact but can also attach themselves to clothing, towels, etc. Therefore, the infected cat must be isolated. Keep the infected cat's items dedicated to them; do not share them with other cats or people. Keep used items clean, and when replacing them, soak them in a disinfectant containing hypochlorous acid (like household bleach) before washing. It is also necessary to clean every day to prevent the spread of pathogens.

Since some diseases can spread between humans, you need to take measures to avoid infecting others, such as not sharing bedding or towels and bathing last.

Does feline skin disease heal naturally?

Depending on the cause, the symptoms of some skin diseases may lighten. For example, with allergic dermatitis, symptoms may improve when the causative substance is removed or during periods with low pollen counts. Also, skin problems caused by stress or psychogenic factors will ease once the stressor is gone.

On the other hand, for infectious diseases, parasites, autoimmune diseases, or tumors, symptoms will not improve without appropriate treatment. Waiting and hoping it resolves on its own can lead to further progression, making it harder to treat, or in the case of tumors, raise the risk of metastasis. If you are even slightly concerned, please visit a veterinary clinic.

Guidelines for visiting a vet for feline skin disease

Symptoms that warrant an early visit

Itching is a source of intense stress and, in severe cases, can reach a level that prevents normal daily life. Therefore, if your cat is scratching frequently, licking, or doing these behaviors more than usual, you should visit a veterinary clinic.

When a cat scratches due to itching, it can lead to scratching the skin raw, bleeding, hair loss, or skin sores. This state requires appropriate medical intervention, so seek veterinary care promptly. If there are other systemic symptoms, such as decreased vitality or appetite, or if the condition is deteriorating rapidly, it may indicate a hormonal disease, autoimmune disease, or tumor, so see a veterinarian as soon as possible. Additionally, as skin diseases that are contagious to other cats or animals can present with similar symptoms, treatment is necessary to prevent the spread of infection.

Skin symptoms caused by tumors include lumps. In the early stages, noticeable lumps may not be visible. By the time you notice a lump, it is often already advanced, so an immediate visit is necessary.

How do veterinarians diagnose feline skin disease?

Medical interview, visual inspection, and palpation

We conduct a medical interview to ask when and what kind of symptoms appeared, as well as history regarding vaccinations, parasite prevention, diet, and outdoor access. We examine the lesions and perform palpation if there are lumps or swelling. We also check for the presence of fleas or ticks. Based on this, we narrow down the necessary tests.

Microscopic Examination

Bacteria and fungi such as Malassezia can be identified under a microscope. Fungi and mites like Sarcoptes can also be confirmed via microscopy.

Fungal Examination

For lesions suspected to be fungal, we perform a Wood's lamp examination, which uses 365nm ultraviolet light to see if the area glows blue-green, indicating dermatophytosis. We may also pluck hairs from the suspicious area to check for fungal hyphae or perform fungal cultures.

Blood Tests

If a hormonal disease is suspected, blood tests are required. These include complete blood counts, biochemical profiles, and hormone testing.

Other Necessary Tests

When hormonal diseases are suspected, some cannot be diagnosed by blood tests alone, so specialized hormone tests or ultrasound examinations are performed. Additionally, for lumps suspected to be tumors, we perform a fine-needle aspiration (FNA) to collect cells, or histopathological examination by removing the lesion itself. These tests are not all performed at once, but are selected based on necessity.

Treatments for Feline Skin Diseases

Pharmacotherapy

Feline skin diseases require different medications depending on the cause. If bacteria are the cause, we use antibiotics; if fungi, antifungal drugs; and if parasites like fleas or ticks are involved, we use parasiticides. If the itching is severe, anti-itch medications such as steroids may be used.

These drugs are prescribed under a veterinarian's instructions. Interrupting medication on your own judgment not only prevents symptom improvement but can also lead to problems like drug-resistant bacteria. Please administer prescribed medications according to your veterinarian's instructions. If you notice any concerning side effects, it is necessary to consult your veterinarian immediately.

Shampoo Therapy

For conditions like bacterial dermatitis or dermatophytosis, we wash the skin with antibacterial or antifungal shampoos. For allergies, we may also recommend shampooing to wash away allergens. Since cats often strongly resist shampooing, we consider whether this therapy is feasible based on the cat's personality and ability to continue. Please follow your veterinarian's instructions regarding the type of shampoo and the frequency of use.

Flea and Tick Control

Fleas and ticks cause allergic dermatitis. To diagnose or rule out this condition, flea/tick preventatives are used in itchy cases. In such instances, use products prescribed by the animal hospital rather than over-the-counter ones.

Dietary Therapy

For allergic dermatitis and atopic dermatitis, you may need to switch to a low-allergen diet. Your veterinarian will prescribe a therapeutic diet. Since it is difficult to improve conditions through diet alone, we often combine diet with medication. Once symptoms improve, it may be possible to maintain the condition with diet alone. If you wish to use commercially available food, you must consult your veterinarian, as their judgment is required.

Addressing Stress and Psychogenic Dermatitis

In cases of stress or psychogenic dermatitis, stress relief is the core of treatment. Since there are many causes of stress, we identify them through a medical interview. We work to remove the stressors and improve the environment so the cat can live with peace of mind. In some cases, we may use supplements or psychotropic drugs to help alleviate stress.

Tumor Treatment

Treatments for tumors vary significantly depending on the type. For example, feline cutaneous mast cell tumors with a low count may be judged to have a favorable prognosis, and we may simply monitor the condition while using anti-itch medication.

For squamous cell carcinoma or fibrosarcoma, surgical removal is the first-line treatment. The extent of removal varies by tumor, but typically includes the tumor and surrounding tissue. However, because fibrosarcoma spreads extremely rapidly, if it is located on a limb, we may perform an amputation. In cases where the tumor has spread too far, radiation therapy may be indicated.

For cutaneous lymphoma, chemotherapy is the first-line treatment.

How to Prevent Feline Skin Diseases?

Flea and Tick Prevention

Even indoor cats can become infested with fleas or ticks. There are cases where fleas attach to cats without the owner noticing. Therefore, regular flea and tick control is necessary even for indoor pets.

Regular Brushing

Regular brushing allows you to notice skin abnormalities early. Furthermore, as cats age, they may lose the ability to groom themselves effectively, leading to dead hair accumulation and subsequent dermatitis. Long-haired or curly-haired breeds can develop mats that cause dermatitis. To maintain healthy skin, brush your short-haired cat once a day and your long-haired cat twice a day.

Regular Skin Checks

Performing regular skin checks helps identify skin diseases early. Make it a routine to feel and check the whole body while brushing or bonding. Observe if the amount of hair loss, any unusual textures, the presence of lumps, or dandruff are different than usual. Also, check the skin for scabs, rashes, or redness.

Creating a Low-Stress Environment

For stress-related or psychogenic skin diseases, it is essential to relieve stress and provide a comfortable living environment. In multi-cat households, each cat needs places to hide or be alone. Incorporating sufficient playtime is also necessary to reduce stress. Since litter box environments can also be a source of stress, provide one more litter box than the number of cats, and use a variety of litter and box types.

Frequently Asked Questions about Feline Skin Diseases

Do not use over-the-counter medication on your own judgment; always use medication prescribed by a veterinarian.

Summary | See a Veterinarian Promptly if You Notice Skin Abnormalities

Feline skin diseases have various causes. Symptoms such as redness, hair loss, itching, dandruff, and scabs differ as well. However, you cannot determine the cause just by looking. Please visit an animal hospital to identify the root cause and receive appropriate treatment. You should also seek medical attention if symptoms worsen or persist.

Some feline skin diseases, such as fungal infections or flea/tick infestations, can be contagious to humans or other animals. To prevent further spread, begin treatment as soon as possible.

Daily brushing and skin checks will help you notice abnormalities early, ensuring a life free from the misery of itching.