Veterinary Medicine - March 2008 - (Page Bayer4)

that is resistant to a product that hasn’t been developed yet.” This statement effectively communicates that the development of resistant genes is a powerful and natural phenomenon. Many veterinarians and pet owners are not aware that flea-control products do not cause resistance—they select for resistant fleas over time. Stated differently, flea-control products kill what they can and leave what they can’t. If the surviving resistant fleas breed successfully, the previously susceptible population becomes a resistant population over time by the selection process. The development of a resistant flea population is dependent upon many cir“Almost all cases of perceived cumstances: the number of fleas on flea-control product failure the pet(s) and in the are caused by something environment, their rate of other than resistance.” reproduction, climatic con—Dr. Byron Blagburn ditions that favor flea survival and reproduction, prolonged exposure to flea-control products, the efficacy and mode of action of the products, and prior exposure of fleas to the class of insecticide contained in the products. Many older products that contained organophosphates, carbamates, or chlorinatedhydrocarbon compounds were applied only to the environment that contained fleas in all life stages. Consequently, the likelihood that these products would select for resistant fleas—if they were present—was great. Newer fleacontrol products applied directly to dogs or cats generally target adult fleas. Because adult fleas represent only 5% of the total flea popula- tion, the process of selection would likely require more time. 3 If a client reports a fleacontrol product failure, what steps should veterinarians tell the client to take? Almost all cases of perceived fleacontrol product failure are caused by something other than resistance. The first step to determine why a client reports failure is to review the medical records and ask questions. Does the problem involve just one pet or are multiple pets in the household? Are all of the pets being treated? Are the pets receiving the correct amount of product at the correct intervals? Is the client applying the product properly? Are the pets predominantly indoor, outdoor, or both? Do the pets swim or receive baths frequently? Do the pets have another dermatologic condition that requires topical therapy? Has the client observed the problem only recently or has it escalated over time? A few simple inquiries will usually identify the problem and give you direction. Some practitioners believe that switching products might produce a more effective result. I usually do not recommend an immediate switch because doing so may result in a new set of compliance problems or subsequent questions about the new product. If the client was initially satisfied with the product, veterinarians should recommend switching to another product only after resistance has been proven via laboratory evaluation of fleas from the pet. The methods described in the imidacloprid study will continue to help us identify resistance and differentiate resistance from other product performance issues. © 2008 Bayer HealthCare LLC, Animal Health Division, Shawnee Mission, Kansas 66201. Bayer and the Bayer cross are trademarks of Bayer. All rights reserved. Cover image by Ryan Kramer. To view this publication online, visit www.advanstarvhc.com/c29 A08168 http://www.advanstarvhc.com/c29

Table of Contents Feed for the Digital Edition of Veterinary Medicine - March 2008

Veterinary Medicine - March 2008 Contents Toxicology Brief Idea Exchange A Challenging Case An Update on Diagnosing and Treating Primary Lung Tumors CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - March 2008

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