I don't know, first off if we can necessarily blame a dog or cat for our entire yard, house and animals suddenly getting a flea problem. Its possible, but it could just be a coincidence. I like to give the benefit of a doubt.
Fact is both homes now have a problem to deal with. In my case, I like to get Frontline, Heartguard or Trifexis so I can treat the dogs and then the dogs walk around and treat the yard. I can't very well poison my yard......I will be poisoning the food my animals eat and will infect my garden with poison, which will eventually land in my plate. Don't think so.
I know I won't eat my dogs, so they have the burden of ingesting the poison, which will rid my yard and their lives of fleas and heart worms.
I also think its a problem that will continue coming back, so from time to time, just re-treat.
I'm not sure guineas would be able to keep fleas under control, but they come to mind. I know they do their share in controlling bugs.....certainly can't hurt, but they sure are stupid.