Understanding Atopic Dermatitis in Dog

LAST UPDATED 20 February 2024

Dogs bring so much joy into our lives and we repay their love by doing everything we can to ensure they are happy and healthy. The scratching and discomfort associated with chronic skin diseases is a common and worrying concern for pets and their carers. Atopic dermatitis, or atopy, is one of these chronic skin diseases in dogs and it is particularly frustrating because it is difficult to diagnose and causes constant scratching, licking and chewing. 

In this comprehensive guide, we will walk you through the cause, clinical signs, diagnosis and treatment of atopic dermatitis so you can be better prepared to manage and alleviate the impact of this skin disease for your beloved pooch.

Contents:

Causes and Triggers of Atopy in Dogs

Atopic Dermatitis is skin disease that affects dogs that have a hereditary predisposition to develop inflamed and itchy skin due to environmental allergens like dust mites, mould spores, grass and pollen. Commonly affected breeds include Staffordshire Bull Terriers, German Shepherds, Labrador, Beagles and West Highland White Terriers and the symptoms usually start when the dog is less than 4 years old.

Dogs can be allergic to a variety of substances or "allergens" that are found in the environment and in food. The immune system of allergic dogs overreacts to these allergens causing skin and/or digestive tract disease. Allergens can enter dogs' bodies by being breathed in and by absorption through the skin or digestive tract. 

Atopic dermatitis is similar to human hayfever and asthma in that they have the same "triggers" and can wax and wane depending on the season due to varying amounts of allergens in the environment.

Symptoms of Atopy in Dogs

The trademark symptom of atopic dermatitis is itchy skin most commonly on the faces, feet, face, armpits, and groin.  The hair on affected areas, particularly the feet, can become stained a reddish brown colour from saliva and dark, thickened skin can occur in dogs that have been affected for some time. Recurring ear infections are another sign of atopy and, in some dogs, this may be the only symptom that they have. 

Typical symptoms include:

• Itching
• Scratching
• Rubbing 
• Licking
• A yeasty smell
• Greasy skin
• Red and/or thickened skin
• Recurring ear infections

Diagnosing Atopy in Dogs

Unfortunately, diagnosing atopic dermatitis can be a long process because it involves excluding all other diseases with similar clinical signs. Diseases with similar symptoms include mite infections, flea allergy and food allergy and, to complicate matters even further, dogs can suffer from these allergies as well as atopic dermatitis. 

Key steps in diagnosing atopic dermatitis include:

1. A thorough physical examination and documentation of patient history by a veterinarian
2. Laboratory tests, including complete blood cell count, biochemical profile, thyroid testing and urinalysis to assess overall health.
3. Skin tests to look for mite infections
4. Treating the dog with an effective flea control product to rule out flea allergy
5. An elimination diet to test for food allergies
6. IgE allergy testing (blood test)
7. Intradermal allergy testing (skin test)

Allergy Tests

Two different types of allergy tests can be used to work out which allergens are responsible for atopic dermatitis in dogs - a blood test or a skin test.

Treatment of Atopic Dermatitis in Dogs

Unfortunately , there is no cure for Atopic Dermatitis and the aim of treatment is to control itching and improve quality of life. There are three main areas that must be addressed for the successful management of Atopic Dermatitis.

Decrease the Immune Response

The most effective way of doing this is called Allergen Specific Immunotherapy. Immunotherapy works by introducing small amounts of allergens over time so that the dog's immune system develops a tolerance to them. Once the allergens that the dog is sensitive to have been identified by a blood or skin test, a customised allergy vaccine is formulated. This is usually administered by an injection under the skin, however, a new method is now available which involves giving drops under the tongue. Approximately 70% of dogs treated with allergy vaccines will have a positive response and this will usually occur within 6 to 9 months of starting treatment. The benefits of immunotherapy are its relative lack of side effects and dogs treated with this therapy don't have to rely on antipruritic (anti itch) medications.

For patients that don't respond to immunotherapy or whose owners do not want to proceed with allergy testing, antipruritic medication is used to decrease the immune response in atopic dogs.

Treat Secondary Infections

Dogs with skin disease frequently have a bad odour which can be described as musty, yeasty or even like dirty socks! Skin (including that which lines the ear canals) produces an oily substance called sebum which retains moisture and protects against harmful pathogens. When skin is inflamed and damaged, it produces large amounts of sebum. Yeasts and bacteria that live on skin use sebum to grow and will increase in numbers when there is more sebum available. It is the overgrowth of these microorganisms that causes the infections and subsequent smell in dogs with skin disease. 

Most effective treatments for skin and ear infections need to be prescribed by your vet after an examination and identification of the cause e.g. yeast and/or bacteria. These treatments include prescription antibiotics and antifungals, prescription ear drops and prescription ointments.

Over the counter medicated shampoos and conditioners which contain antibacterial and antifungal ingredients are also very useful to decrease the number of microorganisms on the skin as well as remove allergens and built up grease and scaly skin.

Improve the Barrier Function of the Skin

The outermost layer of dogs' skin, the stratum corneum, helps retain water in the skin and guard against penetration of unwanted substances like allergens into the body. This "skin barrier" is abnormal in dogs with atopy and their skin lets in allergens more easily, so improving the skin barrier is crucial for decreasing symptoms. Soothing shampoos, particularly those containing ceramides, not only help repair the skin barrier but also remove allergens from the skin. Leave-in conditioners support optimal skin hydration and a healthy skin barrier. 

Essential fatty acids (omega 3 and 6 oils) have a crucial role in the formation of skin and also play a part in regulating inflammation in the body. Supplements and diets containing omega 3 and 6 oils, particularly those found in oily fish, are very useful for supporting the correct function of the skin barrier. There is a wide range of prescription and over the counter diets available containing ingredients which specifically support the skin barrier.

Conclusion

Atopic dermatitis is one of the most common allergic skin diseases affecting dogs world wide. It is caused by an overreaction in the immune system of susceptible dogs to allergens in the environment like pollen, dust mites and moulds. The classic symptom of atopic dermatitis is itchy skin which can get better or worse depending on the season. This is a lifelong problem with no cure, however, early diagnosis and formulation of a treatment plan in close collaboration with your vet will give your atopic dog the best chance of living a happy and comfortable life.

Further Reading

Yeast Infections in Dogs

Best Dog Food for Skin Allergies

Your Guide to Pet Supplements

How to Stop Your Dog Licking Their Paws

Dogs with Sensitive, Itchy Skin