Atopic Dermatitis in Dogs

What is atopic dermatitis

Atopic dermatitis or atopy (although not synonymous in case of humans, could be identical or related in dogs) is a chronic health condition ^[1] characterized by allergic responses like intense itchiness (pruritus), and inflammation of the skin ^[3]. Dogs with atopic dermatitis are genetically more prone to become affected by environmental allergens like dust, and pollens ^[5].

What causes atopic dermatitis

In dogs, it occurs when the skin’s barrier function is impaired due to genetic defects or inappropriate immune reaction ^{[6, 7]} and the skin is exposed to substances like pollen, dust mites, mold spores, and other allergens ^[2]. As a result, the allergens penetrate through the skin, causing inflammation and severe itching ^[7].

So, it can be said that an improper immune response is more directly responsible for causing the condition than the allergens ^[6].

Dogs more at risk

• Puppies and young dogs between six months and three years of age ^[5].
• Genetically susceptible breeds like Chinese Shar-Pei, Golden Retriever, Boxer, Dalmatian, Wirehaired Fox Terrier, Scottish Terrier, Lhasa Apso, Labrador Retriever, West Highland White Terrier, and Shih Tzu ^[5].
• Dogs regularly exposed to tobacco smoke ^[16].

Is it contagious

Atopic dermatitis is not known to be contagious for either dogs or humans, although it might be inherited genetically ^[14].

Signs and symptoms

The symptoms may get worse over time, usually first becoming evident when the dog is 6-18 months old ^{[1, 10]}. The signs are generally seasonal, with most dogs showing them during the spring and fall ^{[4, 5]}. However, some may get the symptoms throughout the year, especially in advanced cases ^[5]. Visible symptoms may include:

• Itching, scratching and licking, mainly underneath the leg joints, as well as on the paws and face ^[1]
• Moist, reddened, or damaged skin on different body parts like the wrists, ankles, muzzle, around the eyes, ears, and groin ^[1] (due to excessive scratching ^[6])
• a foul smell in the skin and coat ^[10]
• Inflamed ears with recurrent infections ^[6]
• Conjunctivitis or inflammation of the eyelid linings ^{[4, 10]}
• Hair loss ^[10]

Sometimes, dogs with this condition may show other signs of allergy like a runny nose or eyes ^[6].

Can it be prevented

Avoiding the allergens may be the best possible preventive measure; however, it will only be possible if a specific allergen can be identified ^[5].

Diagnosis: How to know if your dog has atopic dermatitis

Diagnosis of the atopic disease is based on an assessment of your dog’s medical history, visible symptoms, and any other signs present, as well as a thorough physical examination ^{[1, 5]}. The following tests and procedures may be required:

• Examination of tissue samples (cytology), superficial dead skin layers (skin scraping)
• Looking for fleas or dried flea feces through a process called the flea combing ^[3]
• Applying elimination diet trials, where your dog is prevented from eating certain foods for a specific period, before incorporating those foods back into its diet to see the reaction. This helps in diagnosing a food allergy ^[3]

After the above, a serum or skin allergy testing may be done to determine the possible causative allergens, and deciding the course of treatment and specific immunotherapy necessary ^{[3, 5]}.

Differential diagnosis

• Parasitic infection ^[5]
• Food allergy ^[5]
• Flea allergy ^[5]
• Pruritic microbial overgrowth ^[5]

Atopic dermatitis treatment for dogs

Since atopic dermatitis cannot be cured, treatment involves regular monitoring and lifelong management ^[5]. The treatment options are determined by the cause of the allergic reaction ^[1], the severity of the visible symptoms, and whether these occur in a particular season or throughout the year ^[5].

Treating with immunotherapy (hyposensitization therapy)

Allergen-specific immunotherapy (also called ASIT) is considered to be one of the most efficient treatments, because it helps in lessening the signs of atopic dermatitis without the use of any other medications ^[5]. It involves administering the specific allergens to which your dog is sensitive through allergy drops or injection ^{[1, 5]}. As a result, it may assist in increasing your dog’s tolerance to those allergens, helping decrease the symptoms. It may take 6-12 months for improving the signs ^[1].

Treating atopic dermatitis with medication

For controlling the itching, antipruritic drugs like antihistamines (diphenhydramine, chlorpheniramine, hydroxyzine) [11] and corticosteroids (prednisone, prednisolone) may be given ^[1]. A study has shown that long-term administration of cyclosporine, an immunosuppressive drug, may effectively control itching in dogs ^[1].

Apoquel, a prescription vet allergy medication, may also be used for reducing itching and inflammation ^[9]. In cases where large body surfaces are affected, your vet may prescribe certain anti-allergy sprays ^[1].

Cytopoint, an antibody injection, is a new therapeutic treatment that may aid in reducing itch and other symptoms linked to atopic dermatitis ^[15].

Are there any natural home remedies for atopy in dogs

A research conducted on 48 pet dogs indicated that topical application of polyunsaturated (omega-3 and omega-6) fatty acids (found in oils like sunflower, walnut, and soybean) along with essential oils (lavender, neem, clove, tea tree, as well as cedar bark, peppermint, oregano, rosemary etc.) to the back of their neck once every 7 days for 8 weeks might reduce itchiness ^[12].

Oatmeal, with its anti-inflammatory properties, can be added to your dog’s bath water or applied as a poultice on its inflamed skin for the inflammation ^[13].

Do not try any of these without consulting your vet.

How common is atopic dermatitis in dogs

It is estimated that about 10% to 15% of the total dog population is currently suffering from atopic dermatitis, making it the second most common canine allergic skin disease, only after the flea allergy dermatitis ^{[1, 4]}. Atopic dermatitis is more common in dogs than cats ^[1].