Atopic Dermatitis in Dogs

Atopic dermatitis is a condition of the skin that afflicts ten to fifteen percent of dogs and is an unusually intense, recurrent dermal reaction to an environmental allergen. The severe itching and swelling that are the primary symptoms of atopic dermatitis are instigated by the release of histamine onto the skin by the cells of the immune system. This disorder can be exacerbated by other skin irritations, such as fleas or exposure to chemicals. Atopic dermatitis is a chronic condition that can be managed with lifestyle changes and appropriate medications but can’t be cured.

Atopic dermatitis is also referred to as allergic dermatitis and is an over-reaction of the immune system to an allergen that causes unsightly and uncomfortable skin reactions.

The symptoms of atopic dermatitis are often concentrated on the face and feet as well as underneath the front legs and the groin area. Quite often these symptoms first occur when the canine is between six months and three years old and could include:

• Chronic ear and skin infections
• Conjunctivitis
• Excessive scratching
• Flaking skin
• Foul odor
• Greasy skin
• Hair loss
• Itchy skin
• Obsessive licking or chewing on feet or joints
• Rubbing against the floor
• Swollen skin

Types 

Atopic dermatitis in canines can be linked to a dysfunction in the skin barrier that increases the absorption of the allergens, making the development of an allergic reaction more likely. Certain breeds are genetically predisposed to developing this disorder, and it tends to run in families. Breeds that are known to be prone to developing atopic dermatitis can include: 

• Beagle breeds
• Boston Terrier
• Boxer
• Beauceron
• Cairn Terrier
• Chinese Shar-Pei
• Cocker Spaniel
• Dalmatian
• English Setter
• Irish Setter
• English Bulldog
• Fox Terrier
• German Shepherd
• Lhasa Apsos
• Miniature Schnauzer
• Pug
• Sealyham Terrier
• Labrador Retriever
• Golden Retriever
• Scottish Terrier
• West Highland White Terrier
• Yorkshire Terrier

Although any allergen can develop into atopic dermatitis, certain allergens are more likely to result in this condition than others. The allergens to watch out for in dogs predisposed to this condition may include:

• Animal dander
• Dust
• Dust mites
• Feathers
• Fleas
• Grains
• Household cleaners
• Insects
• Mold spores
• Plant fibers
• Pollen
• Wool

Initial diagnosis of atopic dermatitis is largely a diagnosis of exclusion. The breed of your dog will be taken into consideration, as well as a timeline of the symptoms, and a complete health history. The skin samples from the affected areas will be collected to examine microscopically. This evaluation of the skin cells, referred to as cutaneous cytology, will help the technician rule out other disorders with similar symptoms such as parasitic infestations like mange, yeast infections, or infiltration by fleas. 

In order to define which allergen or allergens are causing the distressing reaction on the skin, additional diagnostic techniques can be utilized. The most common method for diagnosing which environmental allergens are causing the reaction is an intradermal injection test, also known as a patch test. In this test, minuscule amounts of the most common allergens, as well as any that are specifically suspected, are injected under the skin in order to create a small localized reaction. It is best if the patient eliminates as many medications as possible before commencing with a patch test, both to help ensure accuracy  and to prevent cross-reactivity issues.

There is no actual cure for allergies, so the treatment goal with atopic dermatitis is aimed at a reduction of symptoms in order to improve your dog’s quality of life. The first course of action is to eliminate as much of the allergen as possible. With widespread allergens, such as pollens or dust, 100% avoidance may not be possible, but there are ways to reduce the amount of these substances that are in our houses and on our pets. There are a number of filtration products that are designed with the aim of reducing allergens in both the air and water and dogs with atopic dermatitis may benefit from additional bathing with hypoallergenic shampoo to remove any of the allergens from their coats and skin. Specialized shampoos may be employed to reduce the inflammation and itching, including medicated shampoos with added antihistamine and anti-itch properties. 

Immunotherapy is a more standard option for dogs that are bothered by unavoidable or severe allergic reactions that result in atopic dermatitis. Immunotherapy injections are designed to desensitize the patient to the allergens that are causing the reaction and can be quite advantageous for reducing the symptoms of atopic dermatitis, particularly in dogs who begin the treatment while they are young. Recent advancements have been made in sublingual immunotherapy and trials appear promising as well. This procedure may take six to nine months for results to be noticeable, and are dependent on the proper identification of the active allergens.

Your veterinarian will be able to give you specific instructions on how to best treat the symptoms until you are able to eliminate the particular allergen from the environment or until immunotherapy treatments begin working. Instructions regarding oral and topical medication should be followed faithfully, and administration of these preparations may need to be continued, even after the signs and symptoms seem to have disappeared. Bacterial infections are common with skin allergies and in those cases, antibiotics will need to be prescribed. Prematurely quitting these medications before any bacterial infections have been completely eradicated may cause the infection to reoccur.