Definition and Causes of Dermatitis in Cats
Dermatitis in cats, also called “feline miliary dermatitis” or “scabby cat disease,” refers to irritation, inflammation, itchiness and crusting of the skin. It can affect cats in a number of different ways and is one of the most frustrating conditions for their owners. The causes of feline dermatitis are elusive and can vary greatly. They include contact with irritating animal, vegetable or chemical substances, exposure to extreme temperature or weather conditions, mechanical irritation, self-trauma (biting, chewing, scratching), poor nutrition, immune-mediated disorders and viral, bacterial, fungal or other infectious diseases. Allergic reactions to bites from external parasites, including fleas, ticks, mites and lice, or to certain foods, grasses, detergents, plants or other environmental allergens, are also common causes of feline dermatitis. Dermatophytosis, known as “ringworm,” is a fungal infection that affects the hair, nails and skin. It tends to occur more frequently in cats than in dogs and probably is underdiagnosed.
Whatever the cause, dermatitis leads to symptoms that range from mildly irritating to severely painful and incapacitating. Unfortunately, in many cases, the underlying cause of a cat’s dermatitis is never discovered, despite prolonged diagnostic work. In those cases, prescription oral and topical medications may be helpful to soothe the cat’s irritated skin. If not treated, dermatitis can predispose affected cats to developing potentially severe secondary bacterial skin infections.
Symptoms of Dermatitis in Cats
The symptoms of feline dermatitis depend on what causes their condition in the first place and how severely their skin is affected. Most owners notice signs of skin irritation and inflammation in the spring and summer months. The initial symptoms are usually itchiness and skin redness. The cat may scratch more than usual and rub its body on the floor or ground to relieve itching, causing self-inflicted skin wounds. It may also lick at its paws and the base of its tail. Areas around the groin, under the neck and under the armpits often are inflamed and irritated. Sometimes, this behavior becomes frantic. The condition may or may not fluctuate seasonally. Cats with dermatitis often lose hair due to damage to their hair follicles. “Hot spots” can develop, along with skin ulcers, raised red skin eruptions and other sores. The cat’s skin may become oily, or dry and scaly with dandruff. Affected cats can develop infections and a foul odor in their ears. Dermatitis usually is progressive, regardless of its cause, and will continue to worsen if not treated.
Diagnosing Dermatitis in Cats
Dermatitis is an inflammatory, irritating, painful and often pruritic (itchy) condition that can be fairly easy to diagnose but difficult to treat. Cats in particular are prone to developing inflammatory skin reactions from external parasites, bacteria, fungi and food or drug allergens. A number of tests are available to help veterinarians diagnose dermatitis in cats and, hopefully, to determine the underlying cause of the condition. When a cat has inflamed skin, the veterinarian will search for the cause of the problem. This diagnostic journey normally begins with a thorough history and physical examination, focusing on whether any outside factors (fleas, ticks or other external parasites, exposure to any potential environmental allergens, etc.) are easily identifiable as possible causes. Flea bites can cause horrible dermatitis in cats, and demodectic mange mites can cause similar symptoms. The veterinarian will examine the cat’s coat to look for signs of external parasites and probably will perform a fecal analysis to check for internal parasites that could be causing or contributing to a weakened immune system. The veterinarian may also do a skin scraping to identify parasites that have burrowed deep into the cat’s hair follicles. Other initial tests usually include taking swabs of ear residue and examining them microscopically to check for ear mites or other infectious organisms. In some cases, a quick Wood’s lamp test may be performed to see if the cat’s skin has been infected with ringworm.
If no obvious causes of the cat’s dermatitis are found, the search must go on. Blood tests can help to rule out systemic causes of dermatitis, such as immune system disorders. If the results of blood tests are normal, the veterinarian probably will focus on hypersensitivity (allergic) reactions that could cause the skin inflammation. Dietary changes may be recommended to rule in or out possible food allergies, and shampoos or other topical products may be recommended as well.
Treating Dermatitis in Cats
How to prevent, manage or treat feline dermatitis depends on the cause of the condition. All companion cats should be fed a high-quality, well-balanced diet. Medicated shampoos and other lotions or salves often are helpful to moisturize and soothe skin affected by dermatitis and relieve the accompanying itchiness. If an external parasitic, bacterial or fungal infection is isolated, the cat should be treated with topical, oral or injectable medications, which will eliminate the causative organisms and soothe the animal’s inflamed skin. Sometimes, the cause of feline dermatitis is never discovered. Nonetheless, if left untreated, dermatitis can lead to secondary bacterial infections, which can become extremely serious.
Successful treatment of dermatitis in cats requires identifying the source of the condition through a number of available veterinary diagnostic techniques, and then eliminating or removing the source once it is identified. As long as the cause can be addressed, the outlook for cats with dermatitis is excellent. Dermatophytosis caused by Microsporum canis (cats and dogs are the normal hosts of this fungal organism) is a zoonotic disease, which means that people are at risk of becoming infected if they are exposed to an infected cat.