You have asked...There are so many products available for flea control; what are the differences between topical and oral therapeutics?

Topical and oral therapeutics have revolutionized flea control for domestic cats and dogs. In many cases, these new products have eliminated the need to treat indoor and outdoor environments; helped manage flea-allergic dermatitis; and controlled other arthropods, such as ticks and mites. This article expands on reviews of topically and orally administered flea products<sup1–3sup> (Table 1) and discusses whether the active ingredients must be ingested or come into direct contact with fleas.

CONTACT VS INGESTIONMore traditional treatments (such as shampoos, dusts, and sprays) contain carbaryl, permethrin, and synergized pyrethrins and insect growth regulators (ie, methoprene and pyriproxyfen) and are designed to work by contact. Some of these treatments are directed at fleas; with others, the fleas contact residual deposits and are killed.

However, in the past 10 years new chemistries have provided the clinician and pet owner with additional choices (Table 2). Speed of kill and the inhibition of feeding by adult fleas are especially important as they relate to fast knockdown and prevention of flea feeding. The faster an active ingredient inhibits feeding and kills the fleas, the more likely it will prevent flea-allergic dermatitis.

Although many articles have discussed the efficacy of various products, relatively few have addressed whether these therapies kill fleas through contact (ie, topical activity) or ingestion of the toxicant.