Atopy or Atopic dermatitis continues to be one of the most common dermatological disorders afflicting both dogs and cats.
At our referral dermatology specialty practice, 75% of our patients have atopic dermatitis as one of the final diagnosis.
The problem is so common and severe that many drugs have been utilized in an attempt to offer relief to the suffering patient.
The challenge for the clinician is to try and find the right balance between all of the drugs, their cost, efficacy and safety.
The disease continues to generate research, with new therapies being developed as well. The International Task Force on Atopic
Dermatitis developed guidelines in 2010 for the treatment of atopic dermatitis which involve a multifaceted approach including
Treatment of acute flares
Attempt to ID and avoid all triggers of flare
Improve skin & coat hygiene
Treat ongoing pruritus with drug therapy
Allergen specific immunotherapy should be offered when feasible
The diagnosis of atopic dermatitis is not based on any laboratory or skin test but is based on a combination of signalment,
history, clinical signs and the ruling out other causes of inflammatory skin. Minimizing the drugs begins with a certain and
complete diagnosis of all the triggers of the atopic patient.
When attempting to effectively help a patient with atopic dermatitis it is necessary to understand the pathogenesis of the
disease, and teach the client these basic concepts.
In dogs, atopic dermatitis is known to be an inherited type 1 hypersensitivity reaction to
Epidermal barrier defects contribute to the pathogenesis
Bacterial and yeast infections provide additional antigens which exacerbate pruritus
I try and simplify options with clients and explain there are four groups of options for the treatment of atopic dermatitis.
They include supportive therapy, corticosteroids, cyclosporine and allergen specific immunotherapy. The point of this lecture
is how to minimize the corticosteroids and cyclosporine (C&C). Allergen specific immunotherapy is covered in more detail
in a separate lecture. These options are frequently used in combination in order to obtain synergistic effects, which is an
important point to teach clients. In order to use less C&C clients must administer more intensive supportive therapy.
Supportive therapy is always a good place to start when treating a "mildly" affected atopic patient and includes antihistamines,
essential fatty acids, bathing, restoration of the epidermal barrier, control of secondary infections, and potentially topical
A number of antihistamines have been utilized to control pruritus in dogs. Good clinical trials with placebo controls show
the benefits of reducing pruritus ranging from zero to 30%. Many dermatologists will utilize antihistamines as part of the
ongoing maintenance control of atopic dermatitis, but recognize their limited value when treating an acute or intense flare.
Antihistamines which we currently recommend at our practice include cetirizine, amitrpytilline, Clemastine, diphenhydramine,
and chlorpheniramine. Most are available in generic formulation, and are over the counter, which helps keep the cost low.
I usually try 2-3 different antihistamines, but expectations need to be realistic in understanding the value of these drugs
may be in their steroid sparring effects. Remind owners to avoid formulas which contain decongestants and pain relief products.
There are many published reports regarding efficacy of essential fatty acids (EFAs) for the treatment of atopic dermatitis.
Unfortunately many of these studies failed to control, or account for the amount of EFAs in the diet which makes interpretation
and comparison of these studies difficult. Most dermatologist support the use of EFAs in the treatment of chronic atopic
dermatitis. Despite claims to the contrary, currently it is the position of the Task for on Atopic Dermatitis that there
is no evidence of superiority of any particular EFA combination, dosage, ratio or formulation (including enriched diets) to
improve skin and coat quality. As with antihistamines, EFAs are not adequate as a single therapy for atopic dermatitis except
in mildly affected patients. I recommend minimizing other oils or fats such as olive oil or animal fat to minimize competition
for absorption of the EFAs.
Improvement of the epidermal barrier has recently been getting more investigation and implementation. Simply bathing the
atopic patients has many benefits including
Physical removal of antigens
Reduction of bacterial and yeast populations
Repair epidermal barrier defects
• Anti-pruritic effects and cooling hot inflamed skin