Veterinary Medicine - October 2007 - (Page S4)

ARTICLE 2 NEW ADVANCES AND TECHNIQUES DWIGHT D. BOWMAN, MS, PhD DEPARTMENT OF MICROBIOLOGY & IMMUNOLOGY • COLLEGE CORNELL UNIVERSITY • ITHACA, N.Y. OF COMPANION ANIMAL FLEA CONTROL: VETERINARY MEDICINE Companion animal flea control has improved markedly in the last 10 years, primarily because of new products on the market that control fleas successfully.These products have involved the veterinarian in a pet’s health more intimately than when products targeted the environment or were sold for application to pets without the veterinarian’s direct involvement. Before the advent of these products, the veterinarian’s role was mainly to handle pets’ toxic reactions to misapplied products.The veterinarian’s direct role in helping to control flea infestations has made the world of the flea a much less hospitable place than it once was. However, fleas are only beaten back, not completely gone.The most important flea for veterinarians in the United States is Ctenocephalides felis felis, the subspecies of the cat flea found around the world. Other subspecies, such as C. felis strongylus—an even more voracious blood feeder from Africa—have fortunately not adapted to such a worldwide existence.1* Also, the cat flea, Ctenocephalides felis, has forced the closely related dog flea, Ctenocephalides canis, out of existence in most of North America and Europe.2 Therefore, dogs and cats are both hosts mainly to the same species, C. felis.The cat flea is not restricted to dogs and cats, however; it is capable of infesting a number of other hosts, including coyotes, red and grey foxes, bobcats, skunks, several rodents, raccoons, opossums, and ferrets.3 Thus, we must always remember that although we are not seeing cat fleas on pets in a given area, they are liable to be right around the corner or under the house on our semidomestic urban companions: the opossum and raccoon. Even though fleas may seem under control most of the time, frequent recurrences can frustrate pet owners. Fleas may reappear in days, weeks, or even seasonally.The appearance of fleas a few days after a household begins a successful treatment is called the pupal window4 and is typically due to the eclosion of adults from environmentally resistant pupal cocoons. Another problem is the development and persistence of several stages in the flea life cycle in areas where a pet may rest (e.g., on an old blanket in the basement, under the porch, in the yard between the house and the pool). In these places, large numbers of eggs, larvae, and pupae may be present, and if the specific site is not treated, adult fleas may be produced for several weeks to perhaps months— especially if the pet chooses to spend time elsewhere for awhile and, therefore, the adult fleas are not stimulated to leave their protective cocoons. Finally, the cat flea cannot live at temperatures below freezing, but the fleas can survive winters on the bodies of raccoons and opossums.3 Therefore, it is important that clients remain ever diligent and keep their cats and dogs on a prevention program even when there are no apparent fleas in the household. Flea control strategies Initially flea control consisted simply of cleanliness, sunlight, and frequent washing of wooden floors with brine, kerosene, or even gasoline. One researcher suggested that infestations in the house could be eliminated by the elimination of animals, but this solution would be quite difficult for most pet owners.5 Over the past century, flea control in buildings has gone through various manifestations from fumigation (e.g., sulfur, hydrocyanic gas, or naphthalene), to the use of botanical insecticides (e.g., pyrethrum from chrysanthemums and rotenone from the roots of certain bean plants, such as Derris and Lonchocarpus), synthetic derivatives, and finally organophosphate compounds.6 For the treatment of dogs and cats, people early in the control process also recommended dusting pets with rotenone powder (derris powder), rubbing pyrethrum into the fur, or pulverizing naphthalene mothballs and working the powder into the animal’s fur; however, this is a poor option because these highly toxic chemicals can often cause adverse reactions in pets.6 Today, things are much improved.The major products that are approved to kill and repel fleas on dogs and cats have margins of safety well beyond those that were used until just a few years ago; relatively speaking, these new products are remarkably environmentally friendly.Very small portions of topical products are applied to animals—applied once a month.The doses are below the toxic levels of the substances, even if they were to be taken orally. 4

Table of Contents Feed for the Digital Edition of Veterinary Medicine - October 2007

Veterinary Medicine - October 2007 Contents Leading Off The Veterinary Medicine Interview: Dr. Kevin Fitzgerald Toxicology Brief Idea Exchange Animal Sheltering in the United States: Yesterday, Today, and Tomorrow The Euthanasia Problem Offer Basic Behavior Counseling for Every Pet at Every Visit Promote and Perform Early Spaying and Neutering Assist Owners in Selecting the Best Pets for their Lifestyles Champion Animal Welfare in Your Community CE Form Product Review Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - October 2007

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