The diagnosis of Canine Atopic Dermatitis
In your experience, what is the best diagnostic approach to take for cAD?
The medical history and clinical examination will help compile a list of differential diagnoses. To rule out these other potential causes, several tests may be needed, such as skin scraping, blood sampling, fungal culture, microscopic examination, or biopsies. Finally, a food elimination trial followed by a challenge will help distinguish food allergens (AFR) from environmental allergens (cAD).
Does nutrition play any role as part of diagnosis?
The only validated way to identify the food allergens involved in pruritic dermatosis is to avoid feeding them for 8 weeks. This is the elimination phase, which should be followed by a challenge phase if the symptoms have disappeared. If there is a total or partial return of clinical signs following the reintroduction of the allergen, that would prove their involvement.
What upcoming diagnostic tools could be available to assist the diagnosis of cAD?
Collecting medical history, conducting a clinical examination, following the diagnostic decision tree, and implementing an elimination diet trial are the four mandatory steps for diagnosing cAD with Favrot's criteria. There are no other reliable tests for evaluating type 4 hypersensitivity or alterations in the cutaneous barrier. While patch tests, skin prick tests, and IgE serology can help identify allergens, they cannot be used for diagnosis. Some companies are working on creating a combined IgE / lymphocytic activation test, targeting CAFR diagnosis, but as of 2024, they haven't yet achieved it.
What is the best way for general practitioners to proceed with cases that potentially have both cAD and CAFR?
Being allergic to both food and environmental allergens does not change the step-by-step diagnostic approach: complete medical history, ruling out other common causes of pruritus and conducting a food elimination trial. In cases of allergy to both food and environmental allergens, the food elimination trial will show a partial improvement in the dog's clinical signs. This is further reinforced by a relapse during the challenge phase, leading to a diagnosis of both cAD and CAFR.
To learn more, watch the full video!
You could also be interested to watch the following videos:
- Definition and aetiology of canine Atopic Dermatitis
- How to answer common pet owner questions on canine Atopic Dermatitis and Adverse Food Reactions?
- Long term management of canine Atopic Dermatitis and cutaneous Adverse Food Reactions
- Research on the key nutrients in support of the skin barrier
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