In all seriousness I’ve found to treat cats for fleas the best method is a flea comb and a tub of bubbly soapy water.

The cat doesn’t go in the water, instead you sit the cat on your lap, comb it’s fur gently with the flea comb, and when you spot a flea on the comb, you dunk it in the bubbly soapy water.

…the bubbles catch the flea, and make it a lot harder for them to escape. Turns a traumatic soggy moggy time, into a nice combing kill session.

But I take it you just have the pup, so this tips might be for a passer by.