The multimodal approach to canine atopic dermatitis

Pruritus can dramatically affect the quality of life of both patients and their owners. Pet owners have reported that as their pet becomes more itchy, the quality of life for their pet decreases. Different types of allergies can appear the same, and patients can have more than one type of allergy, which can make it difficult to diagnose. But allergic work-up is important to provide comfort and minimize future relapses.

Many problems can increase frustration for allergic dog owners, including odor and visible lesions. Good customer communication from the entire veterinary team can help owners face the reality of chronic disease management, which often involves a multimodal approach.

Why atopic dermatitis occurs

Atopic dermatitis (AD) results from a hereditary predisposition to develop hypersensitivity to environmental allergens, which are not a problem in non-allergic people. Allergens can be dust mites, pollen, dander, insect particles and mold.

Paws, armpits, abdomen, and face are common areas where itching and secondary lesions occur. These areas also tend to have less hair and be more exposed to allergens, which makes topical therapy important. Cutaneous ingestion of allergens is the primary route of exposure in canine AD.

Secondary infections

Infections are a secondary problem associated with allergies. It can be confusing for an owner to understand that allergies and infections are different problems but affect each other. When owners have a clear picture of this relationship, they are often more willing to commit to multimodal therapy, including frequent bathing and ear irrigation.

One of the biggest mistakes in processing an allergic dog is neglecting cytology to identify an infection. Bacterial and yeast overgrowth on the skin or in the ears can increase itching beyond the dog’s allergic itch. Carrying out cytology during an allergic work-up and during follow-up controls is the basis of allergic treatment. Areas of crust, erythema, debris, alopecia, and lichenification should be removed at each exam to identify the appropriate therapy and to prevent certain therapies from appearing ineffective due to the presence of microorganisms.

Epidermal barrier function

Preserving the stratum corneum (top layer of the epidermis) is essential for a healthy skin barrier. The stratum corneum contains corneocytes and intercellular lipid layers that act as the boundary between a dog’s body and the dry environment. An abnormal epidermal barrier allows allergens to penetrate the skin and leads to a cascade of cytokines and other inflammatory mediators that cause itching. Therefore, a multimodal approach, including topical and systemic therapies to improve the epidermal barrier, is beneficial for dogs with AD.

Why topics are important

Topical therapy should always be considered when treating AD in dogs. This includes both during an active pyoderma event and for long-term maintenance to prevent recurrence. Topicals are especially valuable for controlling chronic, recurring cases of Staphylococcal infection to avoid the development of methicillin resistance. Topical therapy can shorten or even eliminate the need for systemic antibiotics.

Certain topical therapies not only decrease the bacterial population and reduce surface repopulation, but also help restore the epidermal barrier. The epidermal barrier in the skin of atopic dogs has been shown to be abnormal, even if it is not lesional. This underscores the importance of using restorative topical products even in well-controlled atopic patients. As part of the maintenance protocol, these products can minimize the use of systemic allergy medications required for treatment.

Foam your atopic patients

Many topical formulations are available. However, bathing with good quality shampoos is the preferred method if the dog allows it and the customer is able to do so. Bathing removes allergens from the surface of the skin, and many ingredients contain antimicrobial properties.

The most common antibacterial agent found in shampoos is chlorhexidine. It is important to use products that contain 3 to 4% chlorhexidine, such as DOUXO S3 Pyo (Ceva), if it is the only active ingredient against Staphylococcus pseudintermedius. However, 2% chlorhexidine has been shown to have a synergistic effect with miconazole when a combination product is chosen.

The frequency of bathing depends on the severity of the case and the willingness or ability of the owner to bathe the animal. If you have a proactive owner, many cases of pyoderma (even if they are resistant) can be managed with a bath log alone. Cases of pyoderma usually benefit from frequent bathing (every 1 to 2 days) followed by weekly maintenance. Contact time is another important aspect of a bath log. Instruct owners to leave the shampoo on the skin for at least 5 to 10 minutes before rinsing it off thoroughly. If an owner cannot bathe or additional topical therapy would be beneficial, alternative formulations such as mousse, sprays, and wipes are available.

Diet for the epidermal barrier function

To avoid the use of systemic drugs, diets are available that can improve the barrier function of atopic dogs through the use of food. Diets include Royal Canin Skin Support, Hill’s Prescription Diet Derm Defense Canine, and Hill’s Prescription Diet Derm Complete. These diets are high in fatty acids and contain a variety of vitamins that have been clinically proven to improve the epidermal barrier and reduce itching in dogs with AD. It is also easy to implement for home owners if the therapy plan is overwhelming for them.

Immunotherapy and antipruritic agents

Allergen-specific immunotherapy (ASIT) is the best long-term treatment for AD. The formulation is based on the results of intradermal or serological allergy tests. ASIT consists of giving a patient gradually increasing amounts of an allergen extract to improve symptoms associated with subsequent exposure to the allergen. ASIT can take up to a year to be fully effective and 60 to 70% of dogs respond positively. When effective, therapy is usually lifelong.

The use of systemic antipruritic drugs is required in most cases of AD in the dog. This can range from keeping the dogs comfortable while ASIT has time to take effect, dealing with seasonal flares, or providing long-term care where needed. Systemic antipruritic options include oclacitinib (Apoquel; Zoetis), canine allergic dermatitis immunotherapy (Cytopoint, Zoetis), ciclosporin (Atopica; Elanco), or corticosteroids. It is important to weigh the benefits and risks of each therapy and recognize that each patient responds individually to different drugs.

How to create the best plan

Each multimodal plan is different depending on the owner and patient. With so many treatment options available for canine AD, the importance of treating the epidermal barrier should not be overlooked. The use of topical therapy and nutritional supplements should be considered with traditional antipruritic therapies to maximize the comfort and maintenance of dogs with AD.

References

  1. Spitznagel MB, Solc M, Chapman KR, Updegraff J, Albers AL, Carlson MD. Nursing staff load for animal dermatological clients: comparison with healthy control persons and relationship to quality of life. Vet Dermacol. 2019; 30 (1): 3-e2. doi: 10.1111 / vde.12696
  2. DeBoer D. The Future of Immunotherapy for Atopic Dermatitis in Dogs: An Overview. Vet Dermacol. 2017; 28) (1): 25-e6. doi: 10.1111 / vde.12416
  3. Cosgrove SB, Wren JA, Cleaver DM et al. Efficacy and Safety of Oclacitinib for the Control of Pruritus and Associated Skin Lesions in Dogs with Canine Allergic Dermatitis. Vet Dermacol. 2013; 24 (5): 479-e114. doi: 10.1111 / vde.12047
  4. Farmer JE. Therapeutic use of fish oils
    for companion animals. J Am Vet Med Assoc. 2011; 239 (11): 1441-1451. doi: 10.2460 / javma.239.11.1441
  5. Watson AL, Fray TR, Bailey J, Baker CB, Beyer SA, Markwell PJ. Food ingredients can play a beneficial role in the dog’s epidermal barrier function. Exp dermatol. 2006; 15 (1): 74-81. doi: 10.1111 / j.0906-6705.2005.00385.x

Ashley Bourgeois, DVM, DACVD, practices at the Portland, Oregon Animal Skin Clinic. She is the owner / shareholder and on the board of the practice group with locations in California, Kentucky, Indiana, Georgia, Australia and New Zealand. Bourgeois is passionate about educating veterinarians about dermatology and work-life balance through their podcast, lectures, and social media presence (@TheDermVet).

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