Thou shalt not turf: How to successfully manage atopic dermatitis in house
Maybe you don’t think you have the time or the chops to treat canine or feline atopy, but veterinary dermatologists Melissa Hall, DVM, DACVD, and Darin Dell, DVM, DACVD, say successful management of atopic dermatitis is well within the realm of the general practitioner—if you break it into chunks. Here are their answers to our top questions on successfully treating and keeping atopy patients in house.
Question: Is immunotherapy for treatment of atopy something a general practitioner can manage, or do you recommend referring to a board-certified dermatologist?
Dr. Hall: Any veterinarian with an interest can manage these cases—however, there are several caveats. First, the use of allergen-specific immunotherapy implies that canine atopic dermatitis (CAD) is due to environmental allergies. But as with many diseases in veterinary medicine, the actual physiology is far from simple. Atopic dermatitis is likely a multifactorial disease resulting from a complex interaction between host and environment. Therefore to treat these cases, we have to take a multipronged approach using both systemic and topical applications.
CAD is also usually progressive, requiring lifelong management, lots of client education, a high level of compliance and an inclusive treatment plan for success. This means the GP has to spend a good amount of time with the clients, which is often difficult in a day full of procedures, exams and walk-in appointments. Board-certified dermatologists often see fewer appointments in the day, so we can spend more time on each case in order to test and educate adequately.
Dr. Dell: I don’t think there’s a black-and-white answer to this question. It’s analogous to the question, “Can a GP perform abdominal ultrasounds?” The answer is, obviously, yes, anyone can buy an ultrasound machine. But if you don’t like ultrasound or only perform two a year, you won’t develop the skill needed to do a great job.
Effective immunotherapy involves more than drawing a blood sample and following the computer-generated recommendations. If a client is interested in immunotherapy, then I think the GP should offer a referral. If the client declines, then proceed with serum allergy testing but contact the company providing the allergy shots and try to learn more about what you’re doing.
Q: Is skin testing still the best option for these patients, or are there other tests out there that are getting good results?
Dr. Hall: For the most part, in vivo intradermal testing is preferred because the results are immediate. However, serum testing has come a long way and is often the preferred testing method for our feline patients. Either way, remember that allergy testing is not considered a major tool in the diagnosis of CAD but instead helps you identify significant allergens to use when you initiate immunotherapy.
Dr. Dell: Skin testing requires sedating the patient and shaving a patch on the side of the thorax, so it isn’t a good option for all patients. But serum allergy test results can be extremely variable depending on what lab you use, what time of year you draw the sample and what the patient is allergic to. A study by Plant and colleagues provides some more details on the difficulties with serum allergy testing.1
Q: How often should we be rechecking these patients in the short term? And what tests do you recommend at recheck, other than history and physical exam?
Dr. Dell: I like to recheck two weeks after starting immunotherapy, then two, four and six months later. If the dog develops any skin lesions or experiences an increase in pruritus, then it needs to be seen sooner. Any abnormalities need to be noted, and areas of irritation or erythema need to be sampled via cytology to search for infection.
Recheck exams also allow you to quiz owners about their injection technique and inspect their antigen vials—sort of like you would do for a diabetic animal. You can encourage the clients during these visits too. Immunotherapy is usually slow and unexciting, so it’s critical to reassure clients they’re on a good path. Last, it’s important to ask open-ended questions about the injection procedure, itch level and pet’s quality of life.
Q: What’s the most common reason for treatment failure?
Dr. Hall: The most common reason I see antipruritic medication fail is concurrent superficial pyoderma, Malassezia dermatitis or both. These patients benefit from routine bathing with a chlorhexidine shampoo. When you’re treating with systemic antimicrobials, make sure to conduct rechecks monthly to ensure response to therapy. For superficial pyoderma, treat pets until one week past clinical resolution, which usually takes about three to four weeks. For allergic pets, perform initial recheck exams monthly—ear and skin cytologic evaluations are strongly recommended.
Q: In the short term, while we’re waiting for immunotherapy to take effect, what can we do to control clinical signs?
Dr. Dell: All of the “core” allergy medications available are safe to use along with immunotherapy. This includes antihistamines, corticosteroids, oclacitinib, cyclosporine and canine atopic dermatitis immunotherapeutic (Cytopoint). The only therapy to avoid is high (immunosuppressive) doses of corticosteroids. Topical therapy with moisturizing and antimicrobial products is usually helpful as well.
Dr. Hall: Cytopoint is not for use in feline patients, and oclacitinib is labeled for dogs only. (I’ve tried using it in refractory feline allergy cases but find that it’s not very rewarding.) For cats, I often still use corticosteroids or cyclosporine.
Q: How should we wean patients off these short-term drugs, and when? If patients are being weaned off the drugs and signs return, what should we do?
Dr. Dell: Fortunately, for drugs like oclacitinib, cyclosporine and Cytopoint, no weaning period is necessary. The most common antihistamines don’t need a weaning period either. On the other hand, corticosteroids need to be weaned, as most veterinarians know.
The earliest I would try stopping adjunct therapy is after two months of immunotherapy. This correlates to my second recheck exam after starting immunotherapy. Depending on the patient and client, I may have them try withdrawing adjunct medications on the first of each following month, then resuming if signs return. Note: It’s rare to be able to stop adjunct treatments after two months of immunotherapy. Most patients need adjunct treatments for 10 to 12 months.
Q: How long do patients need short-term therapy, on average?
Dr. Dell: Response to immunotherapy can take six to 12 months. Consequently, clients should be prepared to use adjunct therapy for at least six months. Every patient is different, of course, so everyone needs to be monitoring the pet closely.
Dr. Hall: I often counsel owners that it takes about a year to even see how well their pet responds to allergen-specific immunotherapy. It’s also important to keep in mind that the seasons are always changing, so even with the best-controlled pet, flares can and do happen.
Q: How often do we need to recheck immunotherapy patients in the long term? What should the recheck include? Is there a need to retest these patients if they’re doing well?
Dr. Hall: If a pet is only receiving immunotherapy and doing well, I tend to recheck yearly. If the case requires other pharmacology to remain controlled, then I recheck twice yearly and strongly recommend routine blood and urine monitoring. If a pet on immunotherapy is doing very well, I don’t recommend retesting.
Q: What if they don’t respond?
Dr. Dell: Unfortunately, some patients don’t. If there is absolutely no response after 12 months, then the allergy serum needs to be stopped or changed. If there’s a partial response, then it might be beneficial to adjust the antigen mix. Many dogs don’t respond completely to immunotherapy but still benefit significantly because you can reduce their allergy medications.
Q: Anything else GPs should know about immunotherapy best practices?
Dr. Hall: The best advice I can give practitioners is to try to recognize these cases earlier rather than later—the earlier we get started on immunotherapy, the better the patients do long term. Also, give yourself time—maybe the first appointment is to address the current itch and secondary infections, but schedule that client for a longer recheck exam so you have time to educate them on allergies and create a long-term maintenance plan that everybody (veterinarian, client and pet) can be happy about.
Dr. Dell: Don’t forget about cats! Cats respond very well to immunotherapy and this option should be offered to them too.
1. Plant JD, Neradelik MB, Polissar NL, et al. Agreement between allergen-specific IgE assays and ensuing immunotherapy recommendations from four commercial laboratories in the USA. Vet Dermatol 2014;25(1):15-e6.