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Expert Q&A: What's new and next in companion animal dermatology

Veterinarian Daniel Morris is a diplomate of the American College of Veterinary Dermatology and professor of dermatology and vice chair for clinical affairs at the University of Pennsylvania School of Veterinary Medicine.

It's been an exciting few years in veterinary dermatology. Can you briefly highlight a few of the most interesting advances?

Indeed, it has! In terms of what primary care veterinarians and veterinary dermatologists would consider exciting advances, I'd have to mention the new therapies for atopic dermatitis/pruritus, and ectoparasites (i.e., fleas, ticks and mites).

For atopic dermatitis, we have two new tools that are changing the landscape of therapeutics. The primary target for both is interleukin 31, now known to be an important mediator of the sensation of itch in dogs. Clinical trials provided evidence of their effectiveness, and the global dermatology community now has extensive collective experience with these compounds. While they are not the panacea and there are caveats to the use and success of each, they truly are revolutionary.

On the anti-ectoparasitic front, we have the new class of insecticidal and acaricidal compounds known as isoxazolines. These have provided new options for elimination/prevention of fleas and ticks in dogs and cats. The oral delivery system for dogs is especially appreciated by pet owners who dislike spot-on products. Although not yet licensed for treatment of mites, these compounds are proving to have excellent efficacy against demodectic and sarcoptic mange, Lynxacarus radovskyi in cats, and others. Published reports are emerging at a rapid pace, and I'm grateful to have an effective and less toxic alternative to daily ivermectin therapy for generalized demodicosis of dogs.

How do specialists in veterinary dermatology complement the care provided by general practitioners?

The "politically correct" response is that we provide an extension of care by working with the client's primary care veterinarian. And that is true. But the complete answer runs deeper than that. When you focus on just one organ system all day, every day, you learn to pick up on very subtle nuances and cues from the pet's history and the gross appearance of lesions. Dermatologists also receive extensive training in dermatohistopathology. When I look at a lesion, I am subconsciously also thinking about what it might look like histologically. Especially with rare diseases, there is no substitute for that type of clinical acumen. It is not innate. It is taught/learned during residency training, and honed with experience. As I tell my clients, primary care veterinarians are the rock stars of our profession; they are expected to know a sufficient amount about everything. I am expected to know everything about a very narrow slice of medicine (spoiler alert: I don't). But you certainly don't want me giving advice on the management of diabetes, glaucoma or cardiomyopathy!

Can you share a bit about an interesting case you've worked on?

Perhaps the greatest challenge facing medicine today is multidrug antimicrobial resistance in bacterial organisms. This includes Staphylococcus spp., which are the etiological agents of most bacterial pyoderma cases in dogs, cats and horses. I was taught that widespread superficial bacterial folliculitis (the most common presentation of pyoderma) could not be resolved without systemic antimicrobial therapy. We are now in the dire situation where we often have no safe treatment options for run-of-the-mill SBF, due to extensive antimicrobial resistance profiles of the Staphylococcus organism.

I will never forget the first case that proved to me that the old treatment paradigm was false. It was a middle-aged Newfoundland with SBF lesions extending from its head to its toes. Culture/sensitivity testing showed that our only options for systemic therapy were amikacin and rifampin. Once I explained the potential toxicity profiles of these drugs (and the cost!) to the owners, they opted to first try topical chlorhexidine. They purchased 2% chlorhexidine solution by the gallon, shaved the dog down to the skin (I'd never seen a naked Newfoundland before!) and applied it undiluted to the entire body, once daily, using a pump-up sprayer from a garden supply store. They also bathed him twice weekly with a chlorhexidine shampoo, with 10 minutes contact time prior to rinsing, to be sure every square inch of his body was treated. In four weeks, he was lesion-free. I couldn't believe it! There is now a published clinical trial from Europe to show that this really is an effective treatment option for many cases.

Given unlimited resources, what companion animal problem would you study and how?

My research interest for many years has been the epidemiology of multidrug-resistant staphylococcal infections. Given unlimited resources, I would fund the development of novel compounds (not just "antibiotics") to treat extensively drug-resistant bacteria, such as staphylococci, Pseudomonas, E. coli, Acinetobacter, etc. All of the buzz about a "post-antibiotic world" isn't just apocalyptic hype. It's real. And it's terrifying.

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