Atopic dermatitis – the eternal itch

Atopic dermatitis, also known as atopy, is an allergic skin inflammation that causes severe itching—similar to neurodermatitis in humans. It is triggered by environmental allergens to which genetically predisposed animals react with an overactive immune system.

INHALT
Causes Symptoms Diagnosis Treatment Prognosis Prophylaxis
Causes

The causes of atopic dermatitis are complex. The tendency to develop it is genetic. It is an environmental allergy, often to pollen, dust mites, or mold. However, non-allergic factors also play a role in the development and severity of the disease. These can include other diseases, stress, or poor gut health. Symptoms only become apparent when several factors come together.

The allergens are either inhaled or penetrate the skin. Animals affected by atopy often have a defective skin barrier. The skin inflammation is then caused by an excessive activation of the immune system.

In most cases, atopic dermatitis develops at an early age, before the age of three. It then persists throughout the animal's life. Breeds particularly affected are terriers, retrievers, French bulldogs, boxers, and German shepherds. In cats, it is most common in Abyssinian and Siamese cats.

Symptoms

The classic symptom of atopic dermatitis is severe itching, usually affecting the entire body. This is noticeable through frequent scratching, licking of the paws, rubbing against objects, shaking of the ears or rolling around. Not every animal has visible skin redness and papules (=small bumps) at the onset. Scratching causes skin injuries, some of which develop into purulent inflammations. As the condition progresses, hairless areas, scaly fur, an unpleasant body odor, pustules, crusts, and leathery thickening and darkening of the skin develop. Recurrent ear infections (see corresponding article) often occur. The disrupted skin barrier often leads to the development of Malassezia dermatitis (=skin inflammation caused by yeast fungi, see corresponding article) or other bacterial skin infections. Depending on the trigger, the symptoms occur year-round or seasonally.

Typical areas of the body are the paws (especially the front paws), ears, flews, edges of the eyes, armpits, inguinal region, lower neck and lower tail. If the rear back or the edges of the ears are affected, this is more likely to be a flea saliva or food allergy.

Dog paw skin inflammation
A typical symptom is skin inflammation on the paws, which are constantly licked.
Diagnosis

After a comprehensive consultation, your veterinarian will perform a general examination. Your detailed preliminary report on the progression of the disease, seasonal occurrence, previous treatments, diseases of related animals, parasite prevention, feeding and much more will form the basis for the diagnosis. Some practices use a special questionnaire for this purpose, which you can fill out at your leisure before the appointment. During the examination, your veterinarian will assess the skin changes and their distribution pattern. Atopic dermatitis is diagnosed using a process of elimination: First, a parasite infestation with fleas or mites is ruled out (see relevant articles). Your veterinarian will also examine your pet for skin infections caused by yeast or bacteria. Next, a food allergy (see corresponding article) must be ruled out by means of an exclusion diet. This process can take many months.

If all other causes have been ruled out, your veterinarian will perform an allergy test for environmental allergens. This can be done with a blood test or an intradermal test (=skin test). For a more accurate intradermal test, various allergens are injected into the skin and the reaction is observed. This test is usually only performed by specialized dermatologists. However, any veterinarian can take a sample for the blood test and send it to a laboratory. However, a positive allergy test result is not sufficient for a diagnosis, as even healthy animals have antibodies against environmental allergens. Your veterinarian will always evaluate the result in conjunction with your preliminary report, the symptoms, and the exclusion diagnoses. It therefore makes little sense to carry out an allergy test immediately without first ruling out all other causes.

Treatment

The aim of treatment is to alleviate symptoms and achieve the best possible quality of life for your pet and, therefore, for you too. Treatment is tailored to each individual animal. It consists of a combination of different medications and often needs to be adjusted. It is always a long-term treatment, usually for life. Good cooperation between the veterinarian and the owner is crucial for successful management of the condition.

The best therapy is to avoid the allergen to which your pet reacts. However, this is usually not entirely possible. If your dog has a pollen allergy, adjust your walks according to the pollen calendar. Wiping or washing your dog's coat after a walk can help. For cats, it may be advisable to restrict their outdoor access. If your pet has an allergy to dust mites, keep your home as dust-free as possible by vacuuming, mopping, and washing baskets, cuddly toys and similar items frequently. If your pet has a food mite allergy, buy smaller bags of food and store it in an airtight container, or avoid dry food altogether.

Treat recurring skin infections consistently with regular external treatment using shampoos, foams, sprays, wipes or gels. Antibiotics (=medication against bacteria) or antifungals (=medication against fungi) are only used in severe infections.

Various medications are used to suppress the immune response and relieve skin inflammation and itching. These are also used in combination. Your veterinarian will create an individual treatment plan for your pet. Glucocorticosteroids, commonly known as "cortisone," can be administered in tablet form, as an ointment or as a spray. There are also other medications that can be administered orally (=via the mouth) and the option of having a monthly injection administered under the skin at your veterinary practice.

To strengthen the skin barrier, there are numerous preparations in the form of shampoos or creams with moisturizing and skin-soothing ingredients. Essential fatty acids also strengthen the skin barrier and reduce skin inflammation and itching. They are applied to the skin or administered with food.

Hyposensitization, also known as specific immunotherapy (SIT), can reduce the reaction to one or more allergens. This involves gradually administering increasing concentrations of the allergen to your pet via a customized solution. This can be done either by subcutaneous injection (=injected under the skin) or via drops or tablets administered sublingually (=under the tongue). The aim is for the immune system to slowly become accustomed to the allergens and no longer react excessively. Initially, treatment is given every one to two weeks, later at longer intervals. Hyposensitization is also a long-term treatment. The full effect usually only becomes apparent after three to five years. Only a few animals become completely symptom-free. However, 60 to 70 percent of treated animals show a noticeable improvement. Unfortunately, this treatment is not successful in about 20 percent of animals. Continue hyposensitization for at least twelve months before discontinuing it due to a perceived lack of effect.

Prognosis

Atopic dermatitis cannot be cured. It must be monitored and treated throughout the animal's life. However, with individualized and consistent long-term management, both the animal and its owner can achieve a good quality of life.

Prophylaxis

Unfortunately, there is no prevention for atopic dermatitis. If triggers are known, you should avoid them as much as possible. It is important to follow the treatment plan exactly and have regular check-ups at your veterinary practice.