Today's Veterinary Practice

JAN-FEB 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 56 CE: CANINE ATOPIC DERMATITIS 100-mg/mL oral solution of cyclosporine (Cyclavance, Virbac, uk.virbac.com ) has recently been approved in Europe for chronic clinical manifestations of atopic dermatatitis. 49 A human vegetable oil- based formulation of cyclosporine (Sandimmune, pharma.us.novartis.com ) shows marked intraindividual and interindividual variation in oral bioavailability in dogs and is not recommended for CAD. 50 Several human generic formulations of cyclosporine are listed by the FDA as being therapeutically equivalent to Neoral; these formulations have not been tested in atopic dogs for bioequivalence or therapeutic efficacy. Extreme caution is recommended with compounding preparations of cyclosporine because product quality and concentration vary markedly among cyclosporine preparations compounded for animals; as a result, a recent state-of-the-art review on cyclosporine use in companion animals discourages use of compounded cyclosporine. 50 Monoclonal antibodies Biological medicine, an intervention pioneered in the last 30 years in humans, involves the use of monoclonal antibodies to target proteins, such as cellular receptors or soluble molecules, involved in disease pathogenesis. Monoclonal antibodies are monospecific antibodies made by identical immune cells with a monovalent affinity: They bind to the same epitope (the part of an antigen that is recognized by the antibody). During the past decade, the molecular signature of human atopic dermatitis has been increasingly understood, particularly with a focus on barrier dysfunction and cutaneous/systemic immune activation, allowing development of more targeted therapies. Recently, a monoclonal antibody capable of neutralizing canine interleukin-31 (IL-31), a cytokine involved in itch in dogs, was developed. Lokivetmab (Cytopoint, zoetisus.com ) is approved for use in dogs in the United States. 51 Injection of lokivetmab reduced the pruritic response for 3 to 4 weeks after injection without adverse effects; itch decreases within 24 to 72 hours ( FIGURE 4 ). The effect on skin lesions was somewhat lower, with roughly half of the dogs achieving 50% reduction in skin lesions. 51 The mechanism of action of lokivetmab is different from that of oclacitinib; lokivetmab binds to IL-31 before it binds to its receptor, thereby preventing the main pruritogenic effect of IL-31. Lokivetmab has the advantage of being extremely targeted. It has a very long half-life and can be safely administered with other drugs for symptomatic CAD therapy. The label allows for repeated SC administration at a minimum of 2 mg/kg, monthly, as needed. 51 Initial experience in my practice suggests lokivetmab may be best used in atopic dogs with itch but not severe skin inflammation. Furthermore, lokivetmab therapy was successful in some patients that had an insufficient response to oclacitinib. Antihistamines H1-antihistamines (hydroxyzine, cetirizine) inhibit the action of histamine by combining with and stabilizing the inactive conformation of the H1 receptor. 1,3 The current conclusion of the International Task Force on Canine Atopic Dermatitis is that there is no conclusive evidence of the efficacy of oral type-1 antihistamines for treatment of active and chronic CAD skin lesions. 1,3 Veterinarians who wish to use type 1 antihistamines should limit their prescription to drugs with a demonstrable antihistamine effect in dogs (eg, hydroxyzine 2 mg/kg q12h or cetirizine 0.5 to 1.0 mg/kg q24h). 1,3 REFERENCES 1. Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the International Task Force on Canine Atopic Dermatitis. Vet Derma tol 2010;21:233-248. 2. Santoro D, Marsella R, Pucheu-Haston CM, et al. Review: Pathogenesis of canine atopic dermatitis: skin barrier and host-micro-organism interaction. Vet Derma tol 2015;26:84-e25. 3. Olivry T, DeBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Vet Res 2015;11:210. 4. Picco F, Zini E, Nett C, et al. A prospective study on canine atopic dermatitis and food-induced allergic dermatitis in Switzerland. Vet Dermatol 2008;19:150-155. 5. Jaeger K, Linek M, Power HT, et al. Breed and site predispositions of dogs with atopic dermatitis: a comparison of five locations in three continents. Vet Dermatol 2010;21:118-122. 6. Hensel P, Santoro D, Favrot C, et al. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res 2015;11:196. Glossary AIT allergen immunotherapy CAD canine atopic dermatitis FDA Food and Drug Administration IL-31 interleukin-31 JAK Janus kinase

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