Spring into Skin: Interview with a veterinary dermatologist
As part of our Spring into Skin season, looking at skin disease and its management, we’ve got a great series of webinars coming up, led by Sarah Warren, BVetMed MSc (Clin. Onc.), CertVD MRCVS, Veterinary Dermatologist.
So, as a taster, we interviewed her on veterinary dermatology and the role of dermatology, drugs, and supplements in veterinary practice…
What made you go into veterinary dermatology as your area of interest?
I’ve been passionate about dermatology since I was in final year at vet school. In fact, I undertook my final year elective project at the RVC in dermatology, working alongside Prof Ross Bond looking at Malassezia and adherence to corneocytes. It was the only exam that I passed with distinction (ever!). Both Prof Ross Bond and Prof David Lloyd were instrumental in inspiring me to develop a keen interest in dermatology. I attended my first World Congress in Dermatology back in 2000 (in San Francisco), when I was just two years qualified. It’s scary that this is over two decades ago now!
I find dermatology a very logical discipline. It makes sense to me. I like the pattern-recognition element of skin disease and the language used to describe lesions and their distribution. I also like the fact that because most skin diseases are chronic and unrelenting in nature, it allows for a real bond to develop between the owner and myself, with continuity of care and education being a key part of managing a case.
What do you think are the biggest dermatological challenges facing vets in practice at the moment?
Time! Skin cases require time in abundance (in most cases!). Rarely is a 10-15 minute consultation long enough to work up a skin case when you consider that cytology (in nearly all cases) is a cornerstone of the diagnostic work up, along with otoscopy, trichography, skin scrapes etc. I would always encourage vets in practice to book longer appointments and/or admissions if necessary, so that time can be dedicated to investigate cases properly. Investing time at the beginning of a case work-up can pay dividends in the long run because cutting corners can be costly and lead to confusion, especially when multiple clinicians are involved.
Secondly, I think that it can be difficult for vets to understand which treatment modality (for allergy) to choose when (e.g. cicloporin versus oclacitinib versus lokivetmab) and how immunotherapy might fit into the long term multimodal approach along with barrier repair, infection control and allergen avoidance.
Finally, I think that the chronic otitis and pododermatitis cases pose a particular challenge, because of the frustrations felt by owners relating to the recurrent and often unrelenting nature of the clinical signs, where perhaps early referral of these cases should be considered.
Allergy testing has developed something of a bad reputation in the profession in recent years – is that justified?
Yes and no! The indiscriminate use of allergy testing should be avoided because it often leads the clinician down completely the wrong path, and results in the owner attributing their pet’s symptoms to the incorrect trigger.
Allergy testing (for environmental allergens) should only be used as a tool to identify allergens for immunotherapy and for avoidance strategies, and after a clinical diagnosis of allergy has been made (primarily by ruling out other causes of pruritus, such as parasites, infection and food allergy). Furthermore, no test is perfect, be it intradermal testing or serological testing. All will generate some false positives and indeed some animals with a firm clinical diagnosis of allergy will be negative. So it does not answer the question “does this pet have allergies?”.
Lack of standardisation is also a problem and all veterinary dermatologists would like to see mandatory regulation of testing methodology and more studies in the future. The one thing we do know is that there is little to no value in using laboratory tests to diagnose food allergy. The food exclusion trial followed by provocation challenge, remains the “gold standard” for diagnosing food allergy.
We’re seeing a lot of novel pharmaceuticals coming onto the market for managing allergic dermatitis – is there a “silver bullet” out there?
Sadly not! The “one size fits all” approach will rarely work. Our increasing knowledge and understanding about the complex pathogenesis of allergic dermatitis and the differences in breed phenotypes means that we still have to work hard to identify the major factors influencing an individual patient’s disease presentation and tailor the treatments we use to that individual, which will also likely need to be adapted and modified over time.
What do you think is the most exciting development/area in dermatology at the moment?
There are a few for me! Firstly, the concept of the microbiome (skin and intestinal) and what we now term “dysbiosis” rather than exogenous “infection”: We know that in healthy dogs there is a rich diversity of bacteria that live as commensal organisms without doing any harm (in fact they may even provide benefits) and that the skin microbiome varies from site to site (e.g. hairy/non-hairy/moist skin), and that a healthy microbiome is essential for tolerance mechanisms. When the skin becomes inflamed, as it does in allergic dermatitis, this inflammation causes a shift in the microbial population on the skin surface leading to an overgrowth in Staphylococci and/or Malassezia, and a much less diverse microbiome.
This “dysbiosis” continues to recur repeatedly if the underlying inflammation is not controlled. I think this concept strengthens our understanding of the disease process and further reinforces the need for the multimodal approach to treatment, where we not only address the primary inflammation but also the dysbiosis by delivering targeted topical therapies (where possible) whilst also addressing the defective skin barrier.
Second would be the possibility of future therapeutics and bringing the idea of “targeted therapy” to a whole new level: At the recent Sydney World Congress, Wayne Rosenkrantz spoke about the concept of “cytokine profiles” or “endotypes. At some point in the future it might be possible to run cytokine profiles on individual patients to identify the major cytokines involved in the disease process. By doing this, we may then be able to select therapies that target those very cytokines, thereby resulting in much improved treatment efficacies and of course increased safety.
The barrier model of canine dermatitis is increasingly being used to justify the use of EFAs. Is that part of the answer, or part of the problem?
Both. The intricate web of interactions that “is” allergy means that skin barrier damage leads to inflammation and that inflammation results in further damage to skin barrier. There is some debate around cause and/or effect, that is, whether skin barrier dysfunction leads to clinical disease or whether clinical disease and inflammation leads to skin barrier dysfunction.
But whatever is the case, it is largely irrelevant, because the result is increased trans-epidermal water loss, increased allergen penetration and altered microbiome. Therefore it would make sense that treatments that help with pruritus and inflammation will also improve skin barrier, and vice versa!
With so many changes in the management of these very common conditions, what’s your advice for vets in practice who want to stay up to date, but have a busy caseload?
Take advantage of bite-sized CPD provision and evening webinars after work, if you’re not too exhausted! There are some brilliant on-line resources too that are freely accessible and summarise the key approaches to allergic skin disease in both dogs and cats. The BVDSG (British Veterinary Dermatology Study Group) is also a fabulous friendly society, affiliated with the BSAVA, that holds meetings twice a year, and a very cost-effective way of keeping completely up-to-date with the latest thinking in dermatology and perfect for the general practitioner with an interest in dermatology.
And of course, we’d suggest you tune into Spring into Skin, click the link below to register: