While chewable flea and tick prevention is a common choice these days, thanks to the range of palatable 'all-in-one' products now available, topical products are a great option for fussy dogs, those that dislike tablets or those at risk of tick-borne disease such as Ehrlichiosis.
Oral flea preventatives are not affected by bathing . If you are using a tablet or chew for your dog's flea prevention, there will be no impact on their bathing schedule.
Using topical treatments for your dog may have an impact on when you can bathe them.
Different topical flea treatments will have different modes of action. When applied to the skin on the back of the neck, spot-on treatments either form crystal matrixes along the coat, disperse through the top lipid layer, or may be absorbed into the bloodstream for full body cover. Depending on the mode of action and the active ingredients present, it can take varying amounts of time for absorption to occur and the product to reach peak effectiveness.
Due to these differences, every topical flea product will have a specific recommendation set by the manufacturer regarding bathing. Most often this will involve how long to wait after applying the product to bathe your dog.