What are the best flea repellant for dogs?

I have two shih-tzus and I'm wondering what are the best flea and tick repellants for them? one of them have fleas already so i need one that'll work quick. and also can you tell me if the repellant you suggest needs to be given by a vet and how much they cost? thanks you!!

You need to speak to your vet about a flea and tick product, for your dog. No one would have any idea how much that prescribed treatment would be. You also need to call out a professional exterminator, and have your entire home and yard sprayed.

Comfortis flea pills are amazing. The only thing I found that kills fleas & keeps them away. Price depends on the dogs size. I get it from my vet, but you can order it from 1-800petmeds.com I think they only sell them in 6 month supplys. It's a little on the expensive side, but it's worth it to get rid of fleas.

Go for Frontline Plus. Its very effective and kills 100% of fleas within 12 hours and will continue to provide long-lasting flea/tick control for dogs + it also prevents future infestations of fleas by breaking the flea life cycle.You can get 3 Pipette from $24.89 @ budgetpetcare but many sites are providing at best rate. Find out from the bellow links.Also make sure you follow given instructions Good luck!