I Didn’t Know That

Q: How can putting a little flea killer on my dog’s neck kill fleas all over his body?

A: Such products work because the liquid diffuses outward through the skin surface, spreading over virtually the entire body. They are applied to the neck so the animal cannot lick them off before they have a chance to spread. Flea collars, in contrast, work because fleas must go past them to get to the mouth, which is a source of water for them. Flea collars are not nearly as effective as the newer drugs.