I went to a conference lead by Michael Dryden (leading flea researcher) and he said for k9's that Capstar will take care of the initial problem best and then Comfortis has the highest efficacy for preventative and to further eliminate the rest of the problem. They are both by Rx only. There is NO flea product out there that kills every stage of the flea life cycle so you MUST keep up on the monthly preventative. Fleas can be dormant for up to a year or so and any vibrations or temp changes can wake them. This means that they will easily come back if you are seeing them now. Keep up on the preventative, treat the environment and all other pets and you should be good to go. Oh and stay away from ANY products containing pyrethrin(sp?), it is poisonous to dogs and is found in most OTC flea meds.
Re: My dog has fleas