Skin disease is common in dogs and cats.

Skin disease in dogs and cats is one of the most common problems for which pets are presented to the veterinarian.

Symptoms of skin disease in dogs and cats

Symptoms of skin disease in dogs and cats vary depending on the cause but may include:

• hair loss
• itching may or may not be present depending on the cause
• changes in the coloration of the skin are possible

If the skin disease is itchy, pet owners are likely to see:

• areas of inflammation on the skin
• scabs on the skin
• "hot spots" - localized areas of inflammation and hair loss, often bloody and painful

Skin disease may make a dog or cat uncomfortable enough to result in irritability or lack of appetite as well.

Causes of skin disease in dogs and cats

There are numerous causes of skin disease in dogs and cats. However, the skin of animals can only react to diseases in a limited number of ways. Therefore, many different types of skin disease may resemble one another and diagnostic testing, sometimes extensive, may be necessary to determine the cause of an individual case of skin disease.

Potential causes of skin disease include:

• parasitic infections, such as fleas, demodectic mange or sarcoptic mange
• bacterial infections
• yeast infections
• atopy ("allergic dermatits")
• food allergies
• seborrhea
• endocrine diseases, such as hypothyroidism or Cushing's disease
• immune disorders, such as pemphigus

Diagnosing skin disease in the dog or cat

There are many different types of diagnostic tests which are commonly performed to help diagnose the cause of skin disease in dogs and cats. The initial physical examination and appearance of the skin, together with the history of progress of the skin disease will lead diagnostic decision-making.

• Skin scrapings (scrapings obtained from the surface of the skin) are used to detect the presence of the mites which are responsible for causing the various forms of mange.
• Skin cytology (an examination of the cells collected from the surface of the skin) help detect bacteria and yeast organisms in the skin as well as various other types of cells.
• Fungal cultures are used to diagnose fungal infections (i.e. ringworm). Bacterial culture and sensitivity testing will help determine which specific types of bacteria are present in the skin and which antibiotics are most likely to be effective in treatment.
• Blood testing may be necessary to detect endocrine or other systemic diseases.
• Dietary trials may be necessary to diagnose a food allergy.
• Flea and mite medication trials may be recommended in an attempt to rule out these parasites as the cause as some parasites may be hard to physically visualize.
• Allergy testing should only be performed once other causes of skin diseases have been ruled out and a diagnosis of atopy has been established. It is only used to identify the substances which need to be included in hyposensitization therapy ("allergy shots"). Allergy testing is not used to diagnose allergies.
• Skin biopsies require surgically removing small sections of skin for microscopic study of the cells and cell layers.

Treatment of skin disease in dogs and cats

The treatment of skin disease in an individual dog or cat will vary depending on the cause of the disease. In cases where the underlying cause can be identified, it should be treated if at all possible. For instance, flea allergy dermatitis (an allergy to fleas which affects the skin) needs to be treated with adequate flea control in addition to controlling any secondary bacterial or yeast infections present on the skin.

Bacterial and yeast infections are almost always secondary to another cause, such as atopy, food allergy or flea allergy. While the bacterial or yeast infection may be successfully treated with proper antibiotics or antifungal medications, symptoms are likely to return unless the underlying cause is corrected. Allergies may be treated with avoidance (as with flea control) or "allergy injections". Atopy may also be treated with immunosuppressive medications, if necessary. Food allergies will likely require a specialized hypo-allergenic diet. A variety of medicated shampoos, lotions, sprays and other topical medications are used to treat skin disease as well.

Endocrine diseases are frequently seen also. Many endocrine diseases cause hair loss without itchiness. As with other causes of skin disease, adequate treatment of the endocrine disease will be necessary in order to correct the resulting skin disease.

Skin disease in dogs and cats may be caused by many different diseases which often appear similar to each other clinically. Diagnostic testing will be necessary in most cases to establish the cause and formulate a successful treatment plan. Treatment may involve symptomatic relief of itchiness but the underlying cause of the skin disease must be addressed as well. Otherwise, the skin disease is not likely to respond favorably to treatment.