The latest on canine atopic dermatitis

The interaction between genes and the environment is what causes atopic dermatitis (AD), a pruritic and inflammatory disease most commonly seen in dogs between 1 and 3 years old but that can also appear as early as 6 months and as late as 6 years, according to Joya Griffin, DVM, DACVD, a veterinary dermatologist in Louisville, Kentucky, and star of Pop Goes the Vet With Dr. Joya on Nat Geo WILD.

“Certain breeds are predisposed, such as the English bulldog, terriers, retrievers, and brachycephalic breeds in general. In my practice, Yorkshire terriers and Shih Tzus are some of the worse cases we treat, and I frequently see German Shepherds. Dogs are often afflicted with recurrent skin infections, and lesions are most common on the muzzle, periocular areas, pinnae, neck, antebrachial areas, and ventrum and axillary regions,” Griffin said in a lecture at the 2022 Atlantic Coast Veterinary Conference, in Atlantic City, New Jersey.¹

Canine AD diagnostics

Canine AD can be frustrating for those owners who want a fast diagnosis because there is no quick and easy way to identify the disease. According to Griffin, neither serum testing for allergen-specific IgE nor intradermal testing alone can be used to diagnose AD.

“Even normal, unaffected animals can have false positive results that are not clinically significant. These tests serve to identify specific allergens that the patient is allergic to in order to formulate allergen-specific immunotherapy for desensitization,” she explained.

“A thorough history, including the age…[at] onset of symptoms, seasonality, current parasitic control, and [whether in contact with affected] animals or humans, is necessary. Ectoparasitic and secondary infections should always be ruled out,” Griffin concluded.

In cases of year-round disease that include gastrointestinal symptoms, teams should also consider cutaneous adverse food reaction (CAFR) as a possibility. But Griffin cautioned that strict protein elimination diets and serologic testing for CAFR should not be used in place of food trials.

Therapeutic advances

During the past 6 years, 2 targeted systemic therapies have been developed to treat canine AD, allowing veterinary professionals to rely less on glucocorticoids and offer safer symptom control. However, these treatments don’t prevent allergic glare or allow for specific-allergen desensitization.

According to Griffin, oclacitinib (Apoquel) and lokivetmab (Cytopoint) target interleukin-31 and offer temporary symptom control, which is great for short-season atopy. “Cytopoint is a caninized monoclonal antibody that binds and neutralizes IL-31 providing rapid antipruritic effects. It can be used in puppies and dogs with comorbidities, where liver or kidney metabolism may be a concern. One study showed Cytopoint was effective in 71% of dogs who failed therapy with Apoquel; however, dogs who failed twice-daily dosing with Apoquel were less likely to respond to Cytopoint injections.² Some cases in this study required repeat dosing every 2 weeks, which was found to be safe,” Griffin noted.

“Both drugs are great due to fast onset of action and limited side effects; however, they are not effective in all dogs and can become expensive with long-term therapy. My preference is to use them for initial symptomatic pruritus relief while beginning immunotherapy or periodically throughout the year as a ‘rescue treatment’ for patients normally stable on immunotherapy when they have seasonal flareups. In time, many patients can discontinue systemic therapy altogether and be maintained on allergen-specific immunotherapy,” she said.

Professionals looking for a good alternative to topical steroids for localized lesions can use topical calcineurin inhibitors, like tacrolimus or cyclosporine.

References

1. Griffin J. Update on canine atopic dermatitis—the new and the tried and true. Presented at: Atlantic Coast Veterinary Conference; October 10-12, 2022; Atlantic City, NJ.
2. Souza CP, Rosychuk RA, Contreras ET, Schissler, JR, Simpson AC. A retrospective analysis of the use of lokivetmab in the management of allergic pruritus in a referral population of 135 dogs in the western USA. Vet Dermatol. 2018;29(6):489–e164. doi:10.1111/vde.12682