Today's Veterinary Practice

JUL-AUG 2017

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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40 PRACTICAL PARASITOLOGY PEER REVIEWED FACTORS TO CONSIDER WHEN DESIGNING A CONTROL REGIMEN Is Specific Environmental Control Necessary? Environmental flea control measures are not necessary in many circumstances if on-animal treatments are performed appropriately. Except in cases of very heavy environmental contamination, the regular application of adulticidal products (especially those using or incorporating products that also control against immature flea life stages) to all animals in the household provides good flea control in an acceptable period. In this case, the environmental flea burden is eliminated indirectly—fleas in the immature stages in the environment continue to develop, but the ensuing adults are killed before they can lay eggs or their eggs are rendered essentially infertile. However, this may not be sufficient in cases of extremely heavy environmental infestation. Although on-animal treatments alone will eventually eliminate the flea population, it may take several months for the resident immature fleas to mature and be eliminated. In these cases, specific environmental control measures may help. Flea eggs are shed off of the animal and are most numerous where the animal rests. Therefore, frequent sweeping or vacuuming of the indoor environment and washing of the pet's bedding helps decrease the number of eggs. Larvae are susceptible to desiccation, so they are typically found in cracks and crevices of floors or upholstery, or in relatively sheltered, moist areas, such as in carpets, in crawl spaces, or under shrubbery. Frequent vacuuming removes some of these larvae indoors. In heavily contaminated environments, treatment of the premises with a product designed for environmental use may be of benefit. Examples include products containing IGR, such as methoprene or pyriproxyfen. Although these agents do not kill adult fleas, they should inhibit immature fleas from progressing to the adult stage. Some evidence suggests that indoor environmental treatment with borate dusts (Fleabusters RX, fleabusters.com ) may have some larvicidal effects, although this is unlikely to be effective as a sole flea control agent. 12,13 Several agents have been advocated for use in the management of contaminated outdoor environments, including the application of entomopathogenic nematodes (which are supposed to kill flea larvae), pyrethroid sprays, or sprays containing the ultraviolet light–stable IGR pyriproxyfen. However, no literature supports the use of nematodes as a flea control agent. Pyriproxyfen-containing agents do inhibit flea development but have no adulticidal properties. Finally, because of the widespread prevalence of pyrethroid resistance, these products may also have limited efficacy. 14,15 Unfortunately, the best solution to minimize the effect of outdoor contamination is probably to limit access by pets and wildlife to "sheltered" areas that could support developing fleas. This may not always be feasible, which is one reason why aggressive on-pet treatment protocols remain the mainstay of effective therapy. Are All the Animals in the Household Being Treated? This would seem to be an easy question to answer, but the answer is not always so obvious. Clients may not volunteer the fact that they have (and are not treating) other animals, or they might think that some animals "don't count" because they are not in direct contact with the treated pet. Many small pet mammals (such as ferrets and rabbits) may harbor fleas yet are often not considered during the development of flea control regimens. 16 Pet dogs and cats that are allowed to roam freely will come into contact with flea-ridden animals and may become reinfested. Client education is very important in these circumstances. Owners must understand that almost any mammalian pet in the immediate environment can serve as a reservoir for fleas, regardless of whether the treated pet comes into direct contact with them, such as "outdoor-only" dogs and cats (including strays). Free-roaming pets should ideally be confined to a more controllable area or at the least should receive very aggressive flea control. Some flea-allergic animals are so sensitive that roaming must be entirely curtailed. Another source of environmental contamination is wildlife. Numerous species of small wildlife (including raccoons, opossums, and skunks) are able to carry fleas and perpetuate their life cycle. Although most pets do not come into direct contact with wildlife, they may have access to areas where these wild animals also go, such as crawl spaces under houses, under shrubbery, or in outdoor sheds and garages. Ideally, both the wildlife and the pet should be excluded from these locations. CONCLUSION Despite the bewildering number of flea control choices available, a few quick questions about each patient can help narrow down the available choices to the 3 or 4 products best suited for your needs.

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