An allergy is an excessive defense reaction of the immune system to certain and normally harmless environmental substances (allergens), which manifests itself in typical symptoms often associated with inflammatory processes.
Flea saliva allergy is the most common. The fleas themselves are rarely found as the cats immediately brush them off their fur. However, the allergic reaction can last for several weeks if, for example, there is still flea excrement in the fur. This allergy can, but does not have to, be more pronounced in summer.
Feed reactions come second. These are intolerances or allergies to individual feed components such as e.g. E.g. chicken, egg, rice, soy, etc. Food reactions can occur in kittens as well as in adult cats that have been fed the same food for years. Gastrointestinal problems such as vomiting, diarrhea, flatulence or constipation can also occur.
The third most common allergy is atopy (environmental allergy). Environmental allergens include pollen from trees, grasses and herbs, as well as dust mites and mold. In the latter case, the symptoms occur all year round, while winter is often the only symptom-free time for people with pollen allergies.
Cats with allergies show four different reaction patterns (diseases) on the skin:
In miliary dermatitis, cats have small scabs on the skin, usually spread over the entire body. They are better felt than seen.
Feline symmetrical alopecia results in complete or partial hairlessness with a symmetrical distribution pattern, e.g. on the abdomen and inner thighs.
In the case of head and neck itching, cats sometimes show extreme itching and inflict significant wounds on themselves by scratching.
The eosinophilic granuloma complex in turn includes various clinical pictures. All show accumulations of eosinophilic granulocytes (a type of inflammatory cell) under the microscope. Eosinophilic granulomas are often found on the ears and paws and in the oral cavity.
Linear granuloma is a raised, crusty, hairless oblong on the posterior thigh that does not seem to bother cats.
The indolent degenerative ulcer is located on the lip and looks horrific but is not painful to the cat.
Eosinophilic plaques are slightly raised, often itchy and weeping spots on the inner thighs and abdomen.
All symptoms can occur individually or in combination and with or without itching.
Cats with itching groom themselves more often, they lick, nibble and pull out their hair or shake their ears. Some cats don’t let themselves be observed. While some cats wound themselves badly, others are so gentle that the skin appears normal and only the hair is missing.
Allergies are always a diagnosis of exclusion. This means that diseases with similar symptoms (such as mites and skin fungi) must first be ruled out. A trial therapy against fleas is always necessary, since a flea allergy can rarely be ruled out, even if no fleas are found on the cat. A food allergy and an environmental allergy can only be differentiated by at least an eight-week elimination diet (see below). If the symptoms do not improve during this time, a feed reaction can be ruled out. A blood allergy test can provide further information about an environmental allergy.
With any allergy, avoiding the allergen as much as possible is the first step.
In the case of a flea allergy, this includes good flea control of all animals in the household, i.e. treating against fleas every 4 weeks all year round.
If a feed allergy is suspected, an elimination diet with subsequent provocation is carried out for at least 8 weeks.
Environmental allergies are the most difficult to treat because allergen avoidance is almost impossible. Desensitization like in humans or dogs is not possible in cats. However, there are many medications available to reduce the inflammation and itching caused by the allergy.