Atopic Dermatitis in dogs

What is atopic dermatitis in dogs?

Atopic dermatitis is an allergy to environmental allergens such as grasses, pollen, mites, and (skin) flakes. About 75% of dogs with atopic dermatitis show their first symptoms between 1 and 3 years of age. It is less common in dogs younger than 6 months or older than 8 years, but it can theoretically occur at any age. Often, this is a congenital condition that manifests later.

Allergic reactions are triggered by allergens. Allergens are substances that the body produces antibodies against and are generally harmless. Some dogs overreact when they come into contact with these substances.

The most common allergens causing atopic dermatitis in dogs are:

• Mites (50–80% of cases), which can cause symptoms year-round
• Pollen (10–30% of cases), which mainly causes symptoms in spring and summer
• Skin flakes from other animals, environmental fungi, and yeasts; these allergies are rare

The exact cause of atopic dermatitis is not fully understood. However, certain breeds are more prone to atopic symptoms, suggesting a genetic predisposition. These breeds include German Shepherds, Labradors, Golden Retrievers, Shih Tzus, Boxers, Terriers, and Shar-Peis.

What are the symptoms of atopic dermatitis?

The primary symptom of atopic dermatitis in pets is itching. Excessive scratching can lead to hair loss, and the skin is often red, with crusts, and pets may suffer from recurring ear infections. In some dogs, ear infections may be the only visible sign of an allergy. Often, the itching is worsened by a secondary bacterial or yeast infection.

Diagnosis of atopic dermatitis

Atopic dermatitis can only be diagnosed by ruling out all other causes of itching. That is why, in animals presenting with itching, we always start by treating for ectoparasites (e.g., fleas) and initiating a hypoallergenic diet for 10 weeks. If the itching persists after these interventions, we proceed with diagnosing atopic dermatitis. In dogs, this can be reliably done with a blood test, while in cats it is unfortunately less reliable.

Treatment of atopic dermatitis

The primary goal in treating atopic dermatitis is to control the allergy and alleviate its unpleasant symptoms. Below, we outline the different ways we achieve this.

1) Desensitization

A desensitization injection is the only treatment for atopic dermatitis that targets the underlying cause. It is also known as immunotherapy. Before starting this treatment, a blood test is performed to determine exactly which allergens the dog is sensitive to. In the laboratory, a solution is then prepared containing the specific allergens to which the dog is allergic. This allergen solution is injected under the skin and stimulates an immune response. The process is repeated until the immune system no longer reacts to these allergens. “Tricking” the immune system is a long-term process; it can take 12 to 18 months before immunotherapy shows results.

The treatment is not 100% effective. Around 70% of dogs experience a reduction in atopic dermatitis symptoms, and sometimes complete remission, while 30% do not respond. Because this therapy exposes the body to the substances it is allergic to, symptoms may initially worsen. In such cases, short-term medication may be needed to relieve itching. Desensitization therapy works best in young animals.

2) Medication

Medication is an effective way to control the symptoms of atopic dermatitis. It is important to understand that these treatments manage the symptoms, not the underlying cause. Possible medication options include:

• Apoquel blocks the transmission of itch signals to the nerves. It works quickly and effectively, with a significant reduction in itching often seen within 4 hours.
• Atopica and/or Cyclavance modulate certain inflammatory cells involved in the allergic response. These medications require approximately 4–8 weeks to take full effect. In severe cases, they are initially combined with prednisone or dexamethasone for the first two weeks. Atopica is given daily at the start. If the response is positive, the dose and frequency are gradually reduced to the level where the medication remains effective. This is determined on a case-by-case basis.
• Cytopoint is administered as an injection, which must be given by a veterinarian. The injection works for about a month, sometimes slightly longer. Once the effect wears off and symptoms return, another injection can be given. Like Apoquel, Cytopoint blocks the transmission of itch signals to the nervous system and typically takes effect within a day.
• Corticosteroids are effective for allergies but unfortunately have many side effects, such as diabetes or Cushing’s disease. When using corticosteroids, it is important to taper to the lowest effective dose. Sometimes, corticosteroids are the only option to control allergies, especially in cats.

3) Restoring the skin barrier

Atopic dermatitis is a multifactorial condition, meaning it has several underlying causes. Therefore, in addition to controlling the allergy or itch, it is very important to restore the skin barrier. This can be supported with omega fatty acids, provided through diet, supplements, or a topical spot-on. Allergy-controlling medications, such as antihistamines, can also be effective in reducing symptoms and improving the dog’s comfort.

Prognosis for environmental allergies

Atopic dermatitis is a congenital condition and does not go away; however, the treatments mentioned above can significantly reduce symptoms. Dogs with environmental allergies are also more prone to secondary infections and ectoparasites. It is therefore important to monitor these closely and treat them when they occur. For the quality of life of a dog with allergies, it is advisable to manage and/or eliminate all factors that may trigger additional itching throughout the dog’s life.

If you have any questions about atopic dermatitis or other allergies, please do not hesitate to contact us.