Dogs have many problems that affect their skin, the largest organ of the body. The skin serves as a barrier to protect the body from infection, dehydration, caustic substances and ultraviolet light. The health and proper function of the skin is dependent on the health and proper function of the other organs in the dog’s body.
There are two categories of skin disease: primary and secondary. Primary skin diseases affect the skin directly, like mange or flea and tick hypersensitivity. Secondary diseases, such as hypothyroidism, initially involve other organs and later begin affect the skin.
The diagnosis and treatment of skin diseases can be difficult and time consuming. Listed below are some common skin diseases and conditions that can affect your dog as well as a short summary of their diagnosis and treatment.
- Allergies: Unlike humans, who usually react to allergies by sneezing, a dog reacts by scratching. Humans and dogs are reacting to an allergen, a substance that causes sensitivity. Most allergens are inhaled, but a few, such as wool, are the contact type. Some common allergens found in food are corn, wheat, soy, beef and dairy products. Early warning signs of an allergic reaction are scratching, licking, biting or rubbing the skin. If not treated promptly, these reactions can develop into an infection, usually characterized by red bumps and pimples, which will need to be treated.
- Bacterial Infection: Bacterial infection is a common, but usually secondary reaction to an underlying disease such as an allergy. Treatment for bacterial infection is usually a round of oral or topical antibiotics. It’s important to get professional help for the bacterial infection while searching for the underlying disease.
- Acute Moist Dermatitis or Hot Spots: The dog usually causes hot spots himself as he attempts to relieve the pain or itch. Treatment begins with a thorough cleaning of the area followed by topical and systemic antibiotics, as well as anti-inflammatory agents.
- Pyoderma: Pyodermas vary in severity and cover a wide range of infections that result in the formation of pus. Treatment is similar to that for hot spots, but typically takes longer to heal. Shampoos and rinses are sometimes helpful.
- Allergic Inhalant Dermatitis or Atopy: Atopy is an extremely itchy skin disease caused by allergies to microscopic particles in the air. It is diagnosed by both clinical presentation and ruling out other causes such as ectoparasites. Dietary supplements, antihistamines and steroids, often used long term, are standard treatment protocol as well as medicated shampoos and rinses. In unresponsive cases, skin allergen testing and hyposensitization may be helpful.
- Ectoparasites (external parasites): External parasites like mites, fleas and ticks break through the skin and allow bacterial infections to occur. They can also cause allergic reactions. Afflictions are diagnosed by observation and examination of skin scrapings under a microscope. The type of parasite detected will dictate the treatment protocol, which is usually a regimen of anti-parasitic drugs and/or the use of medicated shampoos and rinses.
- Fungal Infections: These include Malassezia sp., dermatophytosis (ringworm) and dermal coccidioidomycosis. They are diagnosed by examining skin scrapings, laboratory cultures, and blood tests to identify antibodies. Treatments include antifungal shampoos and rinses in conjunction with topical and systemic antifungal drugs.
- Food allergies: Food allergies that often manifest themselves as skin problems are sometimes difficult to treat. They are usually diagnosed after other possible causes are ruled out and treatment is a time-consuming process of trial feedings of hypoallergenic diets for a minimum of six weeks to try and uncover the specific food that triggers the reaction.
- Irritant Contact Dermatitis: Contact allergies are usually the easiest to diagnose and treat. They are diagnosed by examination of the contact irritant and the physical symptoms of your dog. Treatment normally consists of washing the irritant from the dog and avoiding future contact. If your dog is itching, he can be given steroids for a short time.
- Autoimmune Skin Diseases: These are several autoimmune skin diseases, and they can cause loss of hair, loss of skin pigment and even blindness. Diagnosis is usually done by examination of an excised portion of the diseased skin under a microscope. Treatment consists of steroids and other immune suppression drugs as well as dietary supplementation.
- Secondary Skin Disease: Secondary skin diseases, like seborrhea and hypothyroidism, are diagnosed during testing for the underlying disease. It can often require blood tests, skin biopsies and X-rays. Treatment of the primary condition usually clears the secondary problems.
Diagnosis and treatment
Your dog’s skin problems may often be a combination of two or more of the previously discussed diseases. For example, a hypersensitivity to fleas can lead to pyoderma. The complicated interactions between the skin and other organs make the diagnosis and treatment of skin diseases difficult and time consuming.
Skin scraping is usually the best method of diagnosing various skin infections. A scalpel blade is used to scrape up the top layers of skin. The skin is then viewed under a high-powered microscope.
Blood tests and surgical biopsies are sometimes necessary to diagnose some skin diseases.
Treatment of skin disease may include the use of antibiotics, antihistamines, steroids, topical drugs, antifungal drugs, medicated shampoos and rinses, dietary supplements, special diets and surgical removal of masses. Some therapies may take months to be effective and in some cases, it may be necessary to continue the therapy for the rest of your dog’s life.
Source: Adapted from the American Animal Hospital Association.