What can kill a flea can kill your dog.. I would get the correct size and not risk it.
A friend of mine only used Sergeant flea shampoo on his dog. It turns out his dog was highly affected by the poison in the flea shampoo which killed his dog after 2 days of the dog going through agony. Very sad.. The Vet said many dogs are allergic to the flea shampoos. The moral of the story is be careful of the poison you give your pet.
I personally use Program which is a birth control for fleas. It doesnt kill them only stops the cycle.. I feel its safer for Fido..
