The evolution of flea and tick control has been impressive, while therapeutic options for allergic dermatitis—atopic dermatitis in particular—have made significant strides. Advancements that top the list include single-dose treatments and long-acting gels for canine otitis externa that dramatically improve client compliance, more effective and longer-acting oral flea and tick medications, and new and exciting therapies for the management of canine allergic pruritus, said Jeanne Budgin, DVM, of Riverdale Veterinary Dermatology, Riverdale, N.J. “Many new topical and oral products have emerged with improved speed and duration of kill combined with reduced toxicity,” she said. “The isoxazolines, including Nexgard (afoxalaner), Simparica (sarolaner) and Bravecto (fluralaner) are seeing more widespread use and generally are very safe and effective. And while not labeled for this use in the U.S., there is evidence that they also have good efficacy against demodex, sarcoptes and otodectes mites.” Isoxazolines have set the bar in flea and tick control, said Mike Canfield DVM, Dipl. ACVD, of Animal Hospital of Regency Park, New Port Richey, Fla. “As we learn more about these compounds and their potential uses in veterinary medicine, the class has an even brighter future,” he said. “The newest addition is Bravecto topical solution for cats, which is the first isoxazoline approved for use in our feline patients. We have been excited by this addition and wonder what other roles this ectoparasiticide may plan in the dermatology and parasitology realm.” Environmental and food allergies now are thought to originate with a defect in the barrier function of the skin (environmental allergies) and gut (food allergies), said Kristin Holm, DVM, Dipl. ACVD, of Veterinary Dermatology Consultation Services Inc. in Johnston, Iowa. Therefore, treatment is aimed at improving the barrier function and reducing exposure to the allergens, she added. “For environmental allergies, the skin barrier can be improved through diet—fatty acids, antioxidants—and topical products containing fatty acids, ceramides and lipids,” said Dr. Holm. “For food allergies, the gut barrier can be addressed through diet (probiotics and prebiotics). Intradermal allergy testing followed by immunotherapy is still the gold standard for environmental allergies. Food allergens can be avoided through newer hydrolyzed diets, which provide lower molecular weight amino acids; therefore, they are less likely to stimulate an immune response compared to higher molecular weight protein molecules.” Atopic Dermatitis Trends According to Holm, the most exciting symptomatic treatment for atopic dermatitis targets IL-31, a molecule responsible for triggering the itch receptors on nerves. Apoquel does this by blocking the receptor, whereas the newer once-a-month injectable Cytopoint does this by binding to IL-31 and eliminating it. “Cytopoint is on the forefront of a new class of monoclonal antibody therapy, which is seeing an explosion of new therapies in both human and veterinary medicine,” Holm said. “These therapies have a very specific target, minimizing side effects.” Dr. Budgin also is a fan of both, calling Apoquel a “great addition to our toolbox for the management of canine allergic dermatitis,” and “life changing for many patients.” “More recently, Cytopoint has revolutionized management by targeting and neutralizing IL-31, a cytokine involved in the itch cycle,” Budgin said. “While long-term data is not yet available, Cytopoint is very promising based on its efficacy and mechanism of action; this limits side effects and concerns for use in young animals and patients with comorbidities that may not be candidates for traditional glucocorticoid or Apoquel therapies.” Prior to Apoquel’s introduction, veterinary medicine was desperate for an effective, quick-acting, safe alternative to corticosteroids, said Bruce Hansen, DVM, Dipl. ACVD, of Dermatology & Allergy Services for Animals in Springfield, Va. “Apoquel and Cytopoint finally have satisfied that need—if you make sure secondary infections are cleared,” he said. On the Rise Another area of veterinary medicine that is experiencing a surge in new products is parasitic control. Isoxazolines, a new class of flea and tick compounds that inhibit GABA channels in parasites, are administered orally once a month or once every three months, depending on the product. “An exciting thing about this class of antiparasitics is their activity against Sarcoptes and Demodex mites (which is off-label, though reported in the literature),” Holm said. “Treatment of otitis also has been improved with medications that can be applied in the clinic and continue to treat the ear for a week or more, so the owner doesn’t need to treat at home. All of these products greatly enhance the human-animal bond, as they decrease the number of times the owner needs to medicate their pet, allowing for more positive interactions with them instead.” The GP Partnership Veterinary dermatologists can help general practitioners look like rock stars. When a GP refers early, the pet owner recognizes that their veterinarian only wants the best for their pet and wants to help spend their money wisely, said Holm. “Dermatology problems don’t go away quickly, and bills can quickly escalate to the point of frustration for the owner,” she said. “Dermatologists address the skin problem only and return the client back to the GP for nonskin related problems. Ideally, a treatment plan can be developed that can be carried out for the long-term by the general practitioner, involving the dermatologist as needed in the future. In my experience, pet parents are most satisfied when their GP refers early and least satisfied when they seek self-referral to a dermatologist after several years of no resolution and hundreds (or thousands) of dollars spent.” Most veterinarians believe a team approach is necessary to provide exceptional client and patient care—a mutual goal of both the general practitioner and dermatologist. “The relationship between general practitioners and specialists is vital to the well-being of both clients and patients,” Budgin said. “With open communication, understanding and the mutual exchange of expertise, this can only enhance the care that we provide as veterinarians.” Despite several new therapies to manage canine pruritus, allergic skin disease remains a very common and often difficult condition to manage. In Budgin’s practice, the dog that presents with refractory atopic dermatitis whose condition is poorly controlled with multimodal treatments and suffers from recurrent drug resistant ear and skin infections is probably the biggest challenge. “I correspond with general practitioners almost every day and try and provide continuing education on a regular basis,” she said. “We discuss many aspects of veterinary dermatology including when to refer for specialty care. I learn a tremendous amount from the exchange as well.” Veterinary dermatology specialists should always strive to be open and available for general practitioners to be able to discuss recent advances in veterinary dermatology, and to explain new products, said Dr. Hansen. “When veterinary dermatologists see patients, it is always best if the general practitioner can be included in the treatment program rather than just getting a referral letter,” he said. “This gets both the general veterinarian and the specialists on the same page.” Education and communication are essential in the delivery of complimentary care, which allows the dermatologist and the practitioner to develop a strong relationship, Dr. Canfield said. “The referral community should provide continuing education opportunities for their region and beyond, if possible,” he said. “In the proper setting, this will allow the dermatologist and practitioners to share ideas and concerns while hopefully building confidence in dermatology.” Dermatology therapy studies are likely to continue developing newer monoclonal antibodies targeting a variety of cytokines, possibly providing safer and more effective treatments for a variety of skin conditions, said Holm. “Genetic research will likely increase, possibly leading to treatment of some genetic conditions,” she said. “The future is definitely bright for veterinary medicine, and dermatology in particular.” Canfield’s area of study of late has found multimodal management of allergic skin disease at the forefront. “The rise in multidrug resistant bacterial skin infections, which are often secondary to allergic skin disease, systemic antibiotic alternatives such as topical therapeutics are of great interest,” he said. “More targeted therapeutics to aid in pruritus control could also reduce skin infection rates by reducing trauma and inflammation.” As methicillin-resistant Staphylococcus aureus (MRSA) infections continue to emerge and result in profound treatment limitations, one of the greatest needs for study involves the development of novel therapies for the treatment of drug-resistant skin infections, Budgin said. “New oral—especially topical—therapies, with unique mechanisms of action, are urgently needed,” she said. “Ongoing research into the role of skin microbiome and barrier function in both health and disease continues to unfold. I would like to see more research focused on feline skin disease—antipruritic agents for example—as research and available therapies are more limited in this species.” Still, never forget the basics, Budgin said. For instance, she recently worked on Snowball, an indoor geriatric Persian cat who had escaped outside a few months earlier for several days. Since that time, she had become progressively debilitated, lost 3 pounds of body weight and was noticeably pruritic in the examination room. “A simple skin scraping revealed loads of scabies (notoedric) mites,” Budgin said. “This is very uncommon in my geographical area—most dermatologists will never see a case like this—and admittedly it wasn’t specifically on my initial list of differentials. It is a good reminder to never forget the basics. Snowball is still under treatment but responding great.” The Last Word Antibiotic resistance is a major concern in all of veterinary medicine, but particularly in dermatology. “Most people have heard of MRSA, and dogs have their own version, MRSP—methicillin-resistant Staphylococcus pseudintermedius,” Holm said. “There are other antibiotic-resistant bacteria, but MRSP is the most common. These bacteria tend to become resistant to many antibiotics over time, so treatments of choice usually are topical therapies rather than oral antibiotics. The real concern is that these resistant strains of bacteria appear to be able to confer their resistant genes to different species of bacteria, including those affecting humans. This has truly become a One Health Initiative concern.” l Originally published in the May 2017 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today!
