Atopic Dermatitis

What Is It?

Pets develop itchy skin, hair loss, and recurrent ear infections for a variety of reasons, but the most common cause is a disease called atopic dermatitis. Canine atopic dermatitis is a hypersensitivity or overwhelming immune response to normally harmless substances. Examples of potential environmental allergens include pollens, dust, house dust mites, and molds, while a food allergy is a hypersensitivity to ingredients within the animal’s diet (most commonly the protein source – i.e. chicken, beef, or pork) and not the grains or carbohydrates. About 30% of pets with allergies have both environmental and food allergies.

Symptoms

Both types of allergies can develop at any time during a pet’s life, but symptoms typically begin between 1 to 3 years of age.  While environmental allergies typically cause respiratory signs in humans, animals usually develop skin conditions.  They will be extremely itchy and may lick, scratch, and chew at the affected areas (especially their ears, feet, bellies, and anal area) until they cause self-trauma and secondary infections.  Ear infections, anal gland infections, and bacterial skin infections are common complications in pets with allergies. Pets with food allergies may also have GI upset such as chronic diarrhea.

It is important to remember that signs of allergies can look identical to signs of many other diseases, included parasitic skin infections, ringworm, endocrine disorders such as Cushing’s disease or hypothyroidism, and organ dysfunction. Your veterinarian will recommend some baseline diagnostic tests to rule out other disorders prior to making a diagnosis of atopic dermatitis.

Treatment and Management

Unfortunately, allergies cannot be cured and will require life-long management for most pets.  There are many treatment options to help manage allergic symptoms including antihistamines, supplements, immune-modulating medications, topical therapies and even acupuncture or herbal therapy.  Many pets will require a combination of treatments to help manage their allergies successfully.  Some patients require treatment only during certain seasons, while others require year round therapy.  Since allergies can worsen over time, effective communication will be important to confirm that short-term therapy is meeting our goals and also to continue to adapt our treatment as necessary to prevent “flare-ups.”

• Avoidance: Ideally, avoidance of the offending allergens is the best treatment strategy.  However, this is often difficult, if not impossible, to do.  For patients that have year-round symptoms or do not improve with our initial therapies, we may recommend a food trial with a hydrolyzed protein diet.  A hydrolyzed protein is a protein broken down into its component amino acids so that it is small enough to evade the immune response.  When performing a food trial, it is essential that the diet is fed exclusively for 8 to 12 weeks.  It is also important to understand that even pets with food allergies may also have environmental allergies and thus require additional therapies. 
• Antihistamines: Antihistamines are often a first line therapy to decrease mild inflammation and itchiness.  Some animals respond better to certain antihistamines, so if the initial choice does not seem to help, we may try a different antihistamine.  They are generally well tolerated, though in some cases can cause drowsiness. 
• Fish oils: Most allergic patients will benefit from omega-3 fatty acid supplementation (fish oils).  Omega-3 fatty acids serve to decrease inflammation by inhibiting the inflammatory cascade in the body.  We carry a veterinary product called Welactin in the form of capsules and liquid formulations.  It provides easy, accurate dosing for pets.  If purchasing a human product, a reputable source is recommended to ensure safety and quality control.
• Nutraceuticals: Redonyl Ultra is a soft chew supplement with the naturally occurring lipid compound PEA (palmitoylethanolamide) as its active ingredient.  PEA is naturally produced in the body in response to tissue injury and works to stabilize mast cells, an immune cell that releases histamine and inflammatory substances.
• Immunosuppressant medications: Because atopic dermatitis is caused by an over-exuberant immune system response, using medications that suppress the immune system offers a rapid and powerful means of controlling itch. The most common medications in this group include corticosteroids (such as prednisone) and non-steroid immunosuppressives (such as cyclosporine, or Atopica). These medications have numerous short term and long term side effects, so their use has declined as alternative options have been developed. 
• Apoquel (Oclacitinib):  Apoquel is an immune-modulating medication designed specifically to treat itchiness in canine skin allergies.  Whereas traditional steroids work by suppressing the entire immune system, Apoquel focuses specifically on the molecules involved in inflammation and itch response.  Side effects may include mild gastrointestinal upset during initial use.  Long-term use of this medication may affect organ and immune system health, and clinical monitoring will be discussed to ensure safe use. This medication is only approved for use in dogs.
• Cytopoint: This injection contains a high concentration of antibodies that effectively block molecules involved in the itch response.  This injection does NOT treat the allergy, but rather prevents itching and scratching.  Side effects are considered extremely rare, since the antibodies found in this injection are cleared from the system in the same manner by which naturally occurring antibodies are eliminated.  This injection should provide relief for 4 to 6 weeks in most pets, though some dogs may require a secondary medication for maximal effects. This medication is only approved for use in dogs.
• Treatment of secondary infections: Bacterial and yeast overgrowth are common in pets experiencing an allergy flare-up. While anti-itch medications can be very effective, they usually won’t work in the face of a skin or ear infection. If you are using one of the treatments listed above and your pet is still very itchy, that’s a good sign that your pet might need a vet visit to evaluate whether they might have an infection.
• Topical therapy: Oftentimes, topical therapies such as ear cleaners, antibacterial/antifungal shampoos, wipes, sprays, or mousse can be helpful to physically remove allergens and to prevent secondary skin infections.  There are also some ingredients in certain shampoos to help improve the skin barrier, reduce skin irritation, and reduce itchiness. 
• Immunotherapy: Veterinary dermatologists have the ability to create allergy “vaccines” that train your pet’s immune system to stop overreacting to normal environmental triggers. We are lucky to have a number of amazing dermatologists in the Twin Cities. Please ask us if you would like a referral.

Prognosis

Allergy management is a lifelong process. Pets with allergies cannot be cured, but with the right combination of therapies, their symptoms can usually be well-controlled. With dedicated care, these pets can live very comfortable lives. 

Content prepared by St. Francis Animal Hospital, 1227 Larpenteur Ave. West, Roseville MN. 55113