Known as pinnae, the outer (visible) part of the cat's ear is susceptible to developing thickening, crusting and scaling. Medically it is known as ear edge dermatitis or ear margin dermatitis.
There are a number of causes of crusty, scaly ears in cats. Parasites, allergies, sunburn, and systemic disorders to name a few. Crusty ear margins may be the only symptom your cat has, or you may notice other signs.
A very common ear disorder in cats is caused by ear mites, known as Odotectes Cynotis. Ear mites are most often seen in kittens and outdoor cats. Although they generally live in the ears, they can infect any part of the body.
Symptoms of ear mites include:
- Reddish brown discharge from the ear which may have the appearance of coffee grounds
- Itching and scratching
- Head shaking
- Ear twitching
- Ear odour
- Crusting and scaling of the ears
Diagnosis of ear mites can be tentatively made by the presenting symptoms, confirmation can be made by taking skin scrapings to look for the presence of ear mites.
Treatment of ear mites depends on the severity of the condition and may include solutions to help clean the ears and remove discharge as well as an insecticide to kill the mites. Ivermectin, Milbemycin (MilbeMite), Selamectin (Revolution), Imidacloprid (Advocate). Your veterinarian can recommend the best product for your cat.
Also known as feline scabies, notoedric mange is a rare parasitic infection caused by the Notoedres cati mite. This mite burrows into the cat's skin, laying eggs along the way. Cats become infected by direct contact with an infected cat.
Symptoms of notoedric mange include:
- Intense itching and scratching
- Crusting, particularly along the ear margins this then progresses to the face, neck and other parts of the cat's body
- Self-mutilation can lead to redness, inflammation and bacterial infection of the skin
Notoedric mange is diagnosed by skin scrapings which is examined under a microscope to look for the presence of mites or eggs.
Treatment of notoedric mange is dips, Ivermectin injections or Revolution topical treatment. Longhaired cats may need to be clipped.
There are two species of mite responsible for demodicosis in cats. Demodex cati and Demodex gatoi. The condition affects dogs more than cats and when it does occur, it is usually in immunosuppressed or malnourished animals.
Symptoms of demodicosis include:
- Single or multiple areas of hair loss with crusting and scaly looking patches. Head, ears and neck are most commonly affected
- Generalised demodicosis can affect the entire body as well as the head and ears
- A waxy secretion may be produced by the ears
Diagnosis is made by skin scrapings and swabs from the ears which are examined under a microscope to look for the presence of mites.
Treatment is lime sulfur dips to kill the mite. Other treatments may include Amitraz although it is quite toxic to cats so great care must be taken. All cats in the household should be treated.
Another form of mange to affect cats is sarcoptic mange. This type of mange is far more common in dogs than it is in cats. Caused by the parasitic mite Sarcoptes scabei this mite most often affects kittens and cats living with dogs. The parasite is highly infectious and can live for several days off the host. Symptoms of sarcoptic mange in cats include:
- Small red pustules which burst open and cause thick crusty scabs, any part of the cat can be affected but most commonly it is the ears, chest and belly
- Intense itching and scratching
- Damage to the affected area can result in damage to the skin and possibly secondary infection
Diagnosis of sarcoptic mange is made by skin scraping although it is not uncommon for a result to come back negative.
Treatment of sarcoptic mange in cats is regular lime sulfur dips, Ivermectin or Revolution to kill the mites.
A highly infectious fungal skin infection. Ringworm is one of the most common skin disorders found in cats. It is characterised by circular, raised patches of rough and scaly skin. Hair is broken or missing in affected areas. Ringworm can occur on any part of the cat including the ears.
Diagnosis of ringworm is made by microscopic examination of hairs to look for the presence of fungal spores. Fungal culture is another way to diagnose the disease where samples of your cat's hair are grown on a special culture which enhances fungal growth.
Treatment of ringworm is anti-fungal medications such as Itraconazole and Griseofulvin or lime sulfur shampoos and dips.
Some cats can develop hypersensitivity to insect bites, mosquitoes are the most common culprit, but any biting or stinging insect can produce a hypersensitivity. As your cat scratches the ear can become further damaged exposing the underlying layers to bacteria.
Common symptoms of insect bite hypersensitivity include:
- Crusting around the ear margins
- Localised swelling
Diagnosis of an insect bite is usually made upon physical examination of your cat.
Treatment for insect bites and stings is applying a cold ice pack, cortisone cream and if itching/swelling is a problem an antihistamine such as Benadryl may be used. If the area has become infected, antibiotics may need to be prescribed. Always speak to your veterinarian before medicating your cat.
Also known as solar dermatitis or radiation dermatitis, sunburn can occur in cats, particularly those who have pale skin colouring. The ears and nose are most vulnerable as they have the least amount/no hair. Prolonged exposure to the sun can lead to squamous cell carcinoma (see below).
Initial symptoms include redness and itching, particularly around the ear margins. Over time, with repeated exposure, the skin can become thickened and crusty.
Sunburn is usually diagnosed upon physical examination and a history of exposure.
Treatment of sunburn includes antibiotics and steroid cream and. Limiting your cat's exposure to the sun is the best preventative. Your veterinarian may recommend a topical sunscreen for your cat, do not use sunscreens for humans unless your veterinarian has said it is safe to use. Many contain zinc which is toxic to cats.
Cats repeatedly exposed to the sun can go on to develop solar dermatitis, in which the skin has become chronically damaged. As each summer passes, the ears become progressively worse with a scaling and thickening of the skin, itchiness and ulceration.
Squamous cell carcinoma
Squamous cell carcinoma is a malignant tumour of the skin and one of the most common causes is excess exposure to the sun. Tumours can develop on any part of the body but the ears, nose, mouth and eyelid are the most common locations.
Symptoms of squamous cell carcinoma include:
- Red and crusted sores
- Bleeding ulcers which don't heal
- Dried areas of skin around the growth
- Hair loss in the affected area
A presumptive diagnosis is often made during physical examination, this will be confirmed by biopsy. An x-ray may also be recommended to determine if the cancer has spread.
Treatment of squamous cell carcinoma is surgery to remove the affected area (known as a partial pinnectomy) followed by chemotherapy or radiation therapy. Pain medication will also be prescribed.
There are a number of allergies which can develop in cats with a wide range of symptoms. The most common are:
- Insect - The most common insect allergy is caused by flea bites, which are covered elsewhere on the site. Cats can develop an allergy to any insect bite, the most common (aside from fleas) is the mosquito. Signs of mosquito bites include red and swollen pustule at the site of the bite as well as itching and possible crusting along the ear margins
- Contact - This type of allergy occurs when the cat comes into contact with an allergic substance such as plants, wool, medications (topical), soaps, detergents etc. Signs of contact allergy include non-seasonal itching and scratching, rash, vesicles and papules. Typical areas include the ears, underbelly, chin, and toes.
- Inhalant - As the name suggests, inhalant allergy relates to allergens which are inhaled such as pollens, dust mites, moulds. Symptoms include red and crusty rash, especially around the head, ears, neck and back, itching and scratching and hair loss.
- Food - Cats can develop allergies to any kind of food but the most common are fish, beef, wheat and eggs.
Diagnosis is made by food trials, which involves switching your cat to a novel food to see if symptoms improve and then re-introducing the suspect food to see if symptoms return. Skin prick tests which expose your cat to multiple common allergens by injecting a tiny amount under the skin to see if there is a reaction and specialised blood tests to detect the presence of antibodies to certain allergens.
Treatment is removal of the allergen where possible, antihistamines and steroids to reduce inflammation and itching, and possibly hyposensitisation in which your cat is exposed to minute amounts of the allergen to re-programme his immune system.
Autoimmune skin disorders are thankfully quite rare in cats, but pemphigus is the most common of them all. The cause isn't fully understood but it is thought there may be a genetic component or it could be related to exposure to sunlight or certain medications. There are three types of pemphigus in cats ranging in severity.
Symptoms of pemphigus include:
- Small red spots, hair loss and blister like vesicles which eventually break open and form thick, yellow crusts. The condition starts around the eyes and nose before spreading to the ears, face and other parts of the body
- Affected areas are itchy and painful
- Secondary bacterial infection may also develop
Diagnosis of pemphigus is based on punch biopsy, direct immunofluorescence to look for antibodies and cytological examination of an intact pustule.
Treatment is immunosuppressive therapy, mild cases may be treated with topical corticosteroids, more severe and widespread cases will require oral corticosteroids. A high dose is initially given to produce remission, and once this has occurred the dosage will be tapered back.
Systemic lupus erythematosus
A rare autoimmune disorder which can affect a number of different organ systems of the cat including the skin. Systemic lupus erythematosus (SLE) is caused by the body producing antibodies against itself (known as auto-antibodies) that attack various systems, one of which may include the skin.
When the skin is affected, symptoms may include:
- Multifocal alopecia with crusty skin lesions, particularly around the ears, face and rear legs
- Oral and nasal ulcers
- Paronychia, inflammation around the claw beds
Diagnosis of SLE requires multiple tests which may vary depending on the system affected.
- Routine tests including complete blood count, biochemical profile
- Coombs test to detect the presence of antibodies in the blood
- Antinuclear test which measures antibodies to self-tissue
- Biopsy of a skin lesion
There is no cure for SLE, treatment is aimed at relieving symptoms, when the skin is affected this may involve oral and/or topical corticosteroids to reduce inflammation and itching and limiting exposure to sunlight.
A cat's ears are prone to frostbite if they have access to outdoors in cold temperatures as they have little fur to protect them from the elements. As the temperatures drop, blood flow is diverted from the extremities (including the ears) to preserve core temperature (and protect the vital organs such as the heart and kidneys). Dampness can exacerbate the problem. Frostbite is graded according to the severity. First degree frostbite affects the epidermis (outermost layer of the skin), second degree frostbite affects the epidermis and the dermis, third degree frostbite affects the epidermis, dermis and the underlying tissue.
Symptoms of frostbite include:
- The affected area will be a pale blue-white colour and cold to the touch
- If third degree frostbite has occurred, the area may feel hard to the touch
- The cat may either feel pain in the area or be completely numb
- As the area thaws, the skin will become red and blistered
- In severe cases, the skin will turn blackened as the tissue dies
Diagnosis of frostbite is based on a history of exposure as well as physical signs.
Treatment of frostbite includes:
- Carefully warming the affected area with warm (not hot) towels, this helps to restore circulation
- Your veterinarian may prescribe painkillers to relieve discomfort
- Antibiotics to prevent secondary bacterial infection developing
- If the tissue has died, it will need to be surgically removed