Got an itchy dog? Maybe it is Atopic Dermatitis

February 24, 2017

 

 

What is atopic dermatitis?

Atopic Dermatitis is an allergic skin disease with a genetic basis.  Dogs with atopic dermatitis have generalised sensitivity to environmental allergens.   These dogs are persistently itchy.  Atopic dogs have a poor skin barrier, and treatment to improve the skin barrier can reduce symptoms.  Atopic Dermatitis cannot be cured, we can only control the symptoms.

 

What is the skin barrier, and why is it important in Atopic Dermatitis?

The skin barrier is made up of a layer of skin cells, as well as proteins and fats which surround the cells and hold the cells together.  This skin barrier forms an impervious layer on the surface of the skin, and prevents bacteria and allergens from penetrating into the deeper layers.  It retains moisture in the skin, preventing skin from drying and flaking.

 

When the skin barrier is compromised, the skin is unable to retain moisture, and becomes dry.  Bacteria and yeast are able to invade the deeper layers.  Allergens such as pollens, grass and other environmental irritants can penetrate and cause irritation.  These infections and allergens lead to inflammation in the skin, and this leads to itching.

 

The primary problem in Atopic Dermatitis is a skin barrier malfunction.  These dogs do not have enough good fats and proteins in the skin to form a nice barrier, and this leads to the symptoms of itching and secondary infections.

 

How can we improve the skin barrier?

The skin barrier can be improved via a number of treatments.  Improving the skin barrier may avoid or reduce the amount of medications needed, and will reduce the frequency of vet visits.

 

Diet

 Adding extra Essential Fatty Acids to the diet will improve the lipid layer in the skin and reduce inflammation.  Most dogs will have at least some improvement in itch levels with this simple change.  The correct balance of omega 3 and omega 6 will give the optimum improvement.  Dogs with atopic dermatitis do not have enough of these fats in their skin, and require more of these fats in their diet than dogs without skin disease.  Regular dog food often does not contain enough of these fats for Atopic dogs, and these patients may require a change of diet.  It will take 6-12 weeks to notice an effect from a change of diet in skin quality, so patience is required. 

 

 

Commercial Dog Foods

Some diets for dogs with sensitive skin will contain high levels of these fats.  Delicate Care Skin and Stomach is the main brand we recommend here, and has been formulated to improve skin barrier function.  Many other brands of food designed for sensitive dogs will also contain these good fats, so if you are unsure about you food, please discuss this with a vet. 

 

Dietary Supplements

If you would prefer not to change your dog’s food, it is possible to add these fats to your dog’s current diet.  Commercial products such as Blackmore’s Paws Megaderm can be poured onto your dog’s dinner.  If you do not want a commercial product Canola and sunflower oils also contain a good balance of omega 3 and omega 6 fats.

 

Topical treatments

A variety of topical treatments are available to improve skin barrier function.

 

 
Topical omega 3 and 6

If you are not supplementing your dog’s food with omega 3 and 6, there are topical products that can be used instead.  Blackmores “Essential 6” is a spot on product that can be used as an alternative means of adding these good fats to your dog’s skin.

 

 

Shampoo and conditioner

 

Many shampoos and conditioners designed for sensitive dogs have ingredients that improve the skin barrier.  These complement food additives.

 

Paw’s Nutriderm range contains oatmeal colloids, ceramides and other plant oils.  These products add proteins and fats into the skin, as well and washing away allergens that are contributing to itch.

 

Why is bathing important for treating Atopic Dermatitis?

When we wash a dog, the shampoo lathers and retains many of the microscopic particles that are on the skin causing itch.  If we follow washing with a thorough rinse (5 minutes of running water) we then remove these particles from the skin surface.  This long rinse also reintroduces water to the skin layer, and when followed by a conditioner, provides effective moisturising for dry, atopic skin.

 

In dogs with atopy, there is often some level of infection with bacteria or yeast.  Use of a gentle medicated shampoo will treat these infections, and may eliminate the need for antibiotic or antifungal medications.  We recommend Blackmore’s Mediderm shampoo in these cases as it is effective on the most common causes of these infections, and is less drying or irritant than some of the other medicated shampoos.  If a dog has Atopy severe enough to get skin infection, then we should follow the bath with a conditioner.  Blackmore’s nutriderm conditioner can be used as a rinse, or can be left on, making it easy to use.

 

What other non-medical treatments may help Atopic Dermatitis?

 

Food

In some dogs food allergies can contribute to atopic dermatitis.  Even in dogs where itchy ears are the only symptom, food allergies may be contributing.  The most common ingredients to cause food allergy are the proteins in the food.  In order of frequency, the most likely causes of food allergies in dogs are: Beef, Chicken, Dairy, Lamb and Wheat.  In general other grains are unlikely to be causing allergies in dogs.  Preservatives and other additives almost never cause allergies in dogs.  Dogs with food allergies might also have periodic vomiting or diarrhoea (but not all food allergic dogs).

 

A wide range of novel protein and hypoallergenic diets are available depending on your preference.  The main diets we use are Delicate Care Skin and Stomach, Hills Prescription Diet z/d, and Royal Canin Analergenic.  Foods that are beneficial for atopic dogs where food allergies are not part of the problem include Hills Derm Defence and Royal Canin Skin Support.  Many other foods are suitable for allergy control – if you have questions about the food you are currently using please discuss this with a vet.

 

Parasite Prevention

Dogs with atopy can have a relapse of symptoms if they are affected by parasites, especially fleas.  Good regular flea prevention can reduce risk of relapse.  A wide variety of flea preventatives are available, to decide which one suits you best discuss this with the vet.

 

I have tried all of the above, and my dog is still itchy.  What medical treatments are available?

 

Immunotherapy

Immunotherapy is allergy testing, and allergy vaccinations.  Some dogs with atopic dermatitis may be strongly allergic to a small number of allergens, and may benefit from allergy vaccines.  Unfortunately, a lot of dogs with atopic dermatitis are only mildly reactive to a wide variety of allergens.  These dogs are unlikely to benefit from allergy vaccines

 

Antihistamines

Some dogs respond very well to antihistamines to treat their atopic dermatitis.  This is highly variable between dogs, but if appropriate antihistamines are trialled, they are quite safe for long term use.

Always check with a vet prior to starting antihistamines.  This will ensure not only that the dose is appropriate, but that the medication is safe.  While some human antihistamines can be used safely in dogs, others can cause significant side effects including heart arrhythmias.

 

Antibiotics and Antifungal Medications

As these dogs often develop secondary infections with bacterial and/or yeast, they will from time to time need antibiotics or antifungals to control the symptoms.  Medicated bathing may avoid or reduce this need, but if infections are bad, oral medication is recommended.

 

Corticosteroids (cortisone)

Cortisone is great for reducing itch and inflammation short term, but if used long term there are a wide variety of side effects.  We may often prescribe short courses of this medication when you dog has a bad flare of symptoms, but in general it is preferable to use other treatments for long term control.

 

 

Cyclosporine (Atopica)

This medication is an immune modulating drug.  It dampens the activity of the immune cells that contribute to the itch and inflammation in the skin that cause the symptoms.  It does not improve the skin barrier, but will reduce itching.  Cyclosporine can take 4 weeks to achieve maximum effect.  Cyclosporine is excellent at controlling Atopic dermatitis.  It is however, very expensive.  All of the previously mentioned control methods may eliminate the need for this drug, or at the least would be expected to reduce the required dose.  As it does affect the immune system, regular blood tests to check white blood cell numbers is recommended (1-2 times per year).

 

Oclactinib maleate (Apoquel)

Apoquel is a new drug in Australia for Atopic Dermatitis.  It is cheaper than Cyclosporine (but still quite expensive), and starts working faster.  It works in a different way to the other drugs to reduce itching at the skin and nerve levels.  In most dogs it is very effective, however anecdotally, some patients we have started on this have not improved as much as we would like.  As with Cyclosporine, this medication does not alter the skin barrier, and by following the earlier recommendations you may avoid the need for this medication, or reduce the dose required. 

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