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Managing atopic dermatitis (Sponsored by Iams)
Douglas DeBoer, DVM, DACVD, with the University of Wisconsin-Madison's School of Veterinary Medicine, shares his recommendations on how to manage atopic dermatitis.
What is the main challenge when treating atopic dermatitis?
The main challenge is formulating a lifelong, individualized management plan for each pet based on its unique clinical picture. This usually involves a combination of treatment choices, such as:
Allergen avoidance—While challenging for most environmental allergens, food allergen avoidance is vital for pets with a food allergy component to their disease.
Pruritic load reduction—both identifies and treats all possible causes that contribute to a pet's pruritic response.
Medical treatment of the primary disease—is the use of drugs, such as antihistamines, corticosteroids, or cyclosporine to provide direct relief of the underlying allergy.
Adjunct therapy with topicals and nutraceuticals—antiseptic shampoos or sprays aid in the resolution of infections and help prevent their recurrence.
Allergen-specific immunotherapy—also known as "desensitization" or "hyposensitization," this therapy aims to reverse the underlying immunologic abnormalities present in allergies and to provide long-term relief with little risk of adverse effects.
What is your recommended protocol for medical treatment of the primary disease?
For early, mild atopic dermatitis, I recommend a combination of fatty acid supplementation along with an antihistamine. The next consideration, at least in the short- to medium-term, would be to add an oral corticosteroid to the regimen.
Unfortunately, long-term use of glucocorticoids has adverse effects. So, if possible, suggest alternate approaches for lifetime management, such as allergy testing and allergen-specific immunotherapy, or treatment with oral cyclosporine.
What is your preferred treatment for pets with secondary infections of their ears, feet, or skin?
Bacterial skin infections associated with atopic dermatitis are typically caused by coagulase-positive staphylococci. The initial drugs of choice for such infections are the cephalosporins. Bacterial culture and susceptibility testing is mandatory on any patient that does not respond appropriately to initial therapy.
For yeast overgrowth on the skin, I prefer to treat with a systemic azole drug, such as ketoconazole, fluconazole, or itraconazole. Only the latter two are suitable for cats, due to increased potential for hepatotoxicity with ketoconazole in this species. For pets with ear disease secondary to atopic dermatitis, a topical combination of antibiotic-corticosteroid, with or without an antifungal, is generally used—perhaps empirically at first, based on ear cytology. Bacterial cultures should be performed if initial treatment does not produce the desired results.
What percentage of atopic pets also has food allergies?
Studies generally conclude that between one in eight and one in 20 pets with atopic dermatitis may also have food allergies. For this reason, it is important to perform a hypoallergenic diet trial on all pets diagnosed with atopic dermatitis while establishing their individual, long-term management plan.
What is your rational for feeding a commercial hypoallergenic (novel-protein or hydrolyzed) diet to all pets with atopic dermatitis?
One reason is to establish food allergy as a contributing factor to the disease through a test diet, or as a longer-term maintenance diet when a diet trial has established the presence of food allergy.
Another reason is in addition to the hypoallergenic formulation, many of these diets contain specific ingredients that may help to diminish the inflammatory response in skin, augment cutaneous barrier function, or both in allergic pets, no matter the type of allergy.
For example, feeding a diet that contains high levels of anti- inflammatory fatty acids to a pet with atopic dermatitis, with or without food allergy, may provide partial relief while avoiding the need for fatty acid supplementation via capsules or liquid supplements.
Supplying anti-inflammatory fatty acids through the food source also guarantees client compliance with the regimen and may decrease the total monthly cost for the client.