Mary Allen
Scratching, rubbing, licking, nibbling — allergies cause dogs and cats to itch, which can drive both animals and humans to despair. But a remedy is possible.
What is Atopic Dermatitis?
Atopic dermatitis is a skin disease caused by an allergic reaction to actually harmless substances in the environment (allergens); e.g. by house dust mites or pollen.
In dogs and cats, the excessive immune reaction does not lead to hay fever as we know it, but to itching and inflamed skin, most comparable to neurodermatitis. Symptoms are different in cats than in dogs.
What is Atopic Dermatitis in Dogs?
The first and most important symptom of allergic skin disease in dogs is chronic itching.
Affected dogs typically scratch and chafe their faces, especially around their lips, eyes, and ears. The paws, the front of the legs, armpits, groin, and the anal area also itch and are licked or nibbled. Many dogs work on the itchy spots until they bleed, and some even mutilate themselves (auto-mutilation).
Many dogs affected by atopic dermatitis also suffer from a chronic ear infection (otitis externa).
The result of itchy, inflamed skin in dogs is very quickly a skin infection — with bacteria (staph) and/or yeast (Malassezia) — which further fuels the skin inflammation.
What is Atopic Dermatitis in Cats?
Itching is also the main symptom in cats. However, cats are more likely to lick themselves than scratch like a dog, and they almost always do so on the sly. Many cat owners therefore first notice hairless patches (alopecia) and are not even aware that their cat is actually suffering from itching.
Itching is the most common cause of hairless patches in cats.
Cats can also work on their skin so vehemently when itching that they inflict bleeding wounds (excoriations) on themselves, mostly in the head and neck area. However, skin infections such as those found in dogs are rare.
So-called miliary dermatitis is typical of allergic cats: countless small nodules develop in the skin, which can break open, ooze, and become crusted.
The so-called eosinophilic granuloma complex (EGK) is also a form of atopic dermatitis. The EGK occurs in three forms: some cats develop very typical striated swellings and redness, the so-called linear granulomas, others show eosinophilic plaques: flat skin thickening and redness that can weep and bleed. Still, others develop a so-called indolent ulcer (Ulcus rodents), mostly on the upper lip, which then looks like it has been “eaten up”, but is nevertheless not painful (indolent).
What are the Causes of Atopic Dermatitis?
Genetic predisposition
The fact that some animals develop allergies is based – just like us humans – on an innate predisposition. This hereditary allergy tendency is called “atopy”, affecting dogs and cats “atopic”.
The immune system of topics reacts differently to contact with certain foreign substances than it should. It forms more antibodies of the IgE type, which promote itching and inflammatory reactions in the skin. At the same time, the barrier function of the skin is demonstrably disturbed in topics, so that they tend to have dry skin and allergens can penetrate the skin more easily.
Since the tendency to allergies is hereditary, animals that show allergy problems should never be bred!
Almost every third offspring of a parent suffering from allergies develops an allergic disease themselves. If both parents are allergic, statistically every second puppy from such a mating will develop allergies. Such a high risk of developing an incurable chronic disease cannot be reconciled with responsible breeding – even if the allergy in the parent animals is only mild!