Just Ask the Expert: Those itchy dogs. Which meds should I try first?
Question. I’m confused about when to use steroids and antihistamines as first-line dermatologic treatments and when to try the newer options such as oclacitinib (Apoquel) or Cytopoint. Is cost the only factor, or are there other considerations?
Answer. There are several things to consider when using steroids and antihistamines as a first-line treatment for canine atopic dermatitis. If you asked the majority of veterinary dermatologists whether they thought antihistamines were effective, I think most would say no. Most studies support that. However, specialists see a very different population of animals than general practitioners do—a biased population of animals. So if you asked most general practitioners if antihistamines were effective in mildly allergic dogs, I think they would say yes—for some patients. I do think antihistamines have a role in controlling clinical signs in some dogs, just like fatty acids are effective as a first-line therapy in the population of animals general practitioners see.
Steroids are effective, inexpensive, predictable drugs that, when dosed appropriately, don’t usually have severe side effects in the short term; of course, some dogs develop significant polyuria/polydipsia or polyphagia. So do I think there’s a role for steroids the first time? Of course I do. They work. The disadvantage in addition to the side effects from short-term use is steroids have significant long-term effects such as cystic calculi, proteinuria and pyoderma. The problem is that they are so effective that people want to use them as the foundation of their therapy. And, in humans at least, there’s evidence that steroids damage barrier function with long-term or repeated use, which is already compromised in atopic animals. Steroids are an effective therapy but can damage the skin.
We also have to recognize that our biggest problem with atopic patients is addressing the barrier dysfunction. I like to encourage owners with mildly itchy dogs to bathe the dogs frequently to wash off antigens and irritants, followed by a moisturizer. That can make a significant difference and should also be a part of the first-line therapy.
If you’re seeing a repeat offender, oclacitinib (Apoquel—Zoetis) is an effective, quick-acting, safe therapy, with the caveat that you have diagnosed atopic dermatitis and that these dogs don’t have concurrent pyoderma, Malassezia dermatitis or demodicosis. Cytopoint (Zoetis) is a reasonable drug to use in cases in which Demodex species or cancer is present or if the pet is under 12 months of age. But before using any of these previously mentioned medications, a minimum database should be performed, which includes skin scrapings for Demodex and scabies as well as skin cytologies to identify bacterial pyoderma or Malassezia dermatitis. If the latter two are present, it’s best to treat the secondary infections first to see how much of the pruritus is infection-driven versus allergy-driven.