Veterinary Medicine - March 2008 - (Page Bayer3)

these isolates in Step 2 was not significantly different than the laboratory strains or field isolates. Additionally, none of these isolates progressed to Step 3 in the bioassay. Since the IFSM has never found an isolate showing reduced susceptibility, it has actually never proven or disproven the presence of resistance of C. felis to imidacloprid. The study suggests that if resistance does actually occur, it appears very difficult to find. Figure 1. Hosts from which flea eggs were obtained* 2001 Cat Dog Total 166 70 236 2002 112 25 137 2003 110 38 148 2004 194 51 245 2005 163 33 196 2006 94 23 117 2007 41 19 60 Total 880 259 1139 * Only specimens with complete host information are included. Discussion According to the IFSM,2 clients may develop a false impression about the efficacy of a particular flea-control product because they still see fleas after treatment. But in areas where and years when the flea population is high, these observations will likely occur even if a product is administered properly. A dog or cat could be treated effectively for a month and then contract fleas from an external source after treatment (e.g., from a backyard or another animal). The IFSM group says the veterinary community should be cautious about presuming that perceived flea product failures are caused by reduced susceptibility. The IFSM group says the capability to identify and document susceptibility to flea- control products will provide for a better understanding of the molecular and biochemical basis of resistance. It also says similar susceptibility monitoring programs on other flea control products may be developed in the future. 1. Blagburn BL, Dryden MW, Payne P, et al. New methods and strategies for monitoring susceptibility of fleas to current flea control products. Vet Ther 2006;7:86-98. 2. Data on file, International Flea Susceptibility Monitoring Group, 2007. References From the expert Byron L. Blagburn, MS, PhD, with Auburn University’s College of Veterinary Medicine in Auburn, Ala., shares his opinions on the International Flea Susceptibility Monitoring study. 1 Why are this study’s results useful for veterinarians? Before the development of the procedures described in this study, veterinarians had no valid or convenient laboratory method to differentiate true flea resistance from other causes of perceived flea-control product failure. We have examined the susceptibility of hundreds of isolates of fleas. To date, we have not encountered a flea isolate from pets that we would characterize as resistant to imidacloprid. The study results do not guarantee that resistance to imidacloprid does not exist. However, they suggest that the frequency of resistance to imidacloprid in U.S. and European flea populations is very low—if it exists at all. The results indicate that factors other than resistance are the cause of most product failure reports. Veterinarians should feel more comfortable knowing that we now have valid methods of monitoring the performance of flea-control products. Having these methods in place is an important first step in developing strategies for dealing with resistance—if or when it develops. 2 What can cause resistance to flea-control products? Many misconceptions exist about how fleas develop resistance to flea-control products. Resistance actually develops naturally in a population of fleas by random mutation and recombination of genes during reproduction. One of my favorite quotes regarding resistance is: “Somewhere in the world, a flea already exists Continued on next page

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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