My poodle has a seresto collar and it puts a shield around her ( when visiting family she gets 0 fleas... it’s amazing) i have no choice but to bring my new pup indoors as we live in an upstairs apartment unit....
I used Advantage IIIf you used a spot-on treatment, and then got him wet, then yes, you probably washed most of it off, or at the least, prevented it from spreading properly.
I rescued an 8 week old kitten this past week. She's had four baths with plain shampoo, and has had about a hundred fleas combed out of her. The other animals are getting their flea treatment (Advantage II for the cats, and Nexgard for the dogs) tonight.