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What Is Canine Atopic Dermatitis?

In simple terms, atopic means 'allergic', and dermatitis means 'inflammation of the skin'. Put the two together, and you have atopic dermatitis (AD), a chronic itchy skin disease which can affect both dogs and humans alike. It occurs when the immune system reacts abnormally to allergens in the environment, causing symptoms such as:

• Itching (you may see your dog scratching, rubbing, chewing or biting itself excessively
• Scratch marks (caused by the above)
• Redness (which may or may not be caused by scratching etc.)
• Discolouration of the skin (known as hyperpigmentation)
• Skin thickening (known as lichenification)
• Self-induced hair loss (known as alopecia)
• Atopic dermatitis can be limited to a few areas of the body or widespread over the dog's body, usually the face, feet, ears, folds, friction and flexure areas.*

Atopic dermatitis is a recurrent disease that usually requires lifelong therapy. It is difficult to treat, as many of the traditional treatments are only partly effective and may be associated with side effects.

*Friction sites are the areas that come in contact with the ground. Flexure points are the patches of skin covering the bent portions of the joints.
 

How Common Is Canine Atopic Dermatitis?

It isn't known exactly how many dogs suffer from atopic dermatitis. However it is relatively common and the indications are that 10 to 15% of dogs may be affected.

Most cases of atopic dermatitis in dogs begin between the ages of 6 months and 3 years.  It is common for the disease to begin as a seasonal condition and progress to a year-round problem over time.

Causes Of Atopic Dermatitis In Dogs

There are thought to be a number of factors involved in causing atopic dermatitis.

The fact that atopic dermatitis often appears at a young age suggests that some dogs have an inherited, genetic predisposition to the disease. Genetic factors are also thought to be important in predisposing certain breeds of dog to develop the disease. West Highland White Terriers, Bull Terriers, Boxers, Dalmatians and Retrievers are all thought to be at higher risk.

It is thought that atopic dermatitis occurs in most dogs when their immune cells react to allergens in the environment, such as:

• House dust mites
• Pollen
• Mould
• Insects

and, possibly: 

• Skin surface microbes

Secondary skin infections, such as Staphylococcus and Malassezia are common in dogs with atopic dermatitis. These are believed to worsen symptoms and contribute to the level of itch.

Diagnosing Atopic Dermatitis In Dogs

Diagnosing atopic dermatitis in dogs is based on exclusion of other disorders. Symptoms such as itching, scratching and hair loss can have other causes, including:

• Flea Allergic Dermatitis (go to the Fleas section to learn more)
• Scabies
• Food allergy
• Bacterial or fungal skin infection

For this reason, a visit to your veterinarian is essential if your pet is suffering the symptoms described on this site. Even if they suspect atopic dermatitis, they'll need to rule out other causes of itching with a detailed patient history, physical examination and some simple diagnostic testing.

Nearly all dogs will suffer a flea infestation at some point in their lives, and many dogs with atopic dermatitis are also allergic to fleas. So whether they're the cause of the problem, or contributing to it, fleas need to be dealt with first.

If canine atopic dermatitis is confirmed, there are a number of different treatments your veterinarian may recommend, many of which are explained in the treatments section of this site

Treatments For Atopic Dermatitis In Dogs

Atopic Dermatitis is a complex disease and often multiple treatments are used together to provide effective control of symptoms with minimal side effects.

 

Immunomodulator
A specifically developed medication is available from your veterinarian which will target the immune cells involved in the allergic reaction, providing long-term control of the allergic response in your dog's skin. This medication has been proven, through extensive trials, to be very effective, well-tolerated, and may reduce the need for concurrent treatments with other medications. This treatment may be given lifelong if necessary.

Immunotherapy
This involves injecting the dog with increasingly large doses of allergens identified during a skin test, causing them to build resistance. Injections are usually administered at home, and the animal may take up to 9 months to respond to the treatment. This therapy may prevent recurrence of flares but usually needs to be administered lifelong.

Steroids
Whilst steroids are generally effective at reducing or eliminating itching, they may also be associated with a number of side-effects, both in the short- and long-term. Some patients develop an insatiable appetite. Others, excessive thirst and urination. Hair thinning, liver damage, and skin and urinary tract infections may also be associated with prolonged use. Thus they are better used for the short term control of itching. Provided they are used appropriately (i.e. at the minimum dose, after other complicating diseases have been controlled), side effects can usually be minimised.

Antihistamines
Antihistamines may help control itching, especially in conjunction with other treatments, however they rarely provide adequate control on their own. Furthermore, since dogs respond differently to different antihistamines, several types may have to be prescribed in an attempt to find an effective one.

Food supplements
There are several veterinary products containing essential fatty acids which have been found to help reduce itching in some dogs. They are known to have few side effects, and because of this are often used as a supplementary treatment.

Topical therapies
Topical therapies, consisting of shampoos, rinses and topical anti-itch solutions offer immediate, but only short-term relief. However, they are often used effectively in conjunction with drug therapies.

Antibiotics
Antibiotics are often used to fight secondary infections, and are usually given as tablets.

Long-Term Management Of Atopic Dermatitis In Dogs

There is no cure for atopic dermatitis in dogs. However, with commitment, it can be successfully managed.

Probably the single most important thing in terms of successful long-term management is to follow your veterinarian's advice rigidly, and make sure any medication is kept up and given on time. It can be tempting to stop treatment when symptoms improve. Do not stop treatment unless advised to do so by your veterinarian. Without treatment symptoms will almost certainly recur, and that will mean misery for you and your dog.

Long-term, you may also be told to make allergen avoidance a major part of caring for your pet. It depends on the allergen identified as being the cause of the problem. Pollens, for example, get everywhere and can be very difficult if not impossible to avoid.

However, if the allergen is house dust mites, you may be told to:

• Wash the dog's bedding regularly
• Wash soft furnishings regularly
• Prevent the dog from spending time in the bedroom (where house dust mites may colonise in greater numbers than elsewhere in the house).
• Frequent vacuuming with a high efficiency particle air (HEPA) filter vacuum cleaner.
• Use of air dehydration and purification systems.
• Use of insecticides effective against house dust mites.

In some cases, these measures may be sufficient to reduce your pet's exposure to allergens by enough to prevent itching.

It is a good idea to maintain rigorous flea control at all times, as flea bites may cause a flare to occur, particularly if your dog is allergic to flea bites