I now use Simpatico on my three dogs - very happy with it. I have one rescue with a bad flea allergy, who then turned out to have an itchy skin reaction to one of the active ingredients in Advocate (my previous spot on treatment) so I had "go back" to a treatment that was not as comprehensive called Advantage, but add in more oral wormers. Simpatico is much better.
I know of two dogs locally who died last year of lungworm, one was a lovely spaniel in my dog training group, the owners were only a few weeks behind with treating the dogs, but it takes hold quickly. As I have one puddle drinking dog as well as the one with flea allergies then having a regular flea and worm treatment is essential.
It helps that the dogs think of the pills as treats, they clearly taste good and I don't have to chase them round the house to administer it !
Oh and I've had dogs for 30+ yrs (about 13 dogs in all) and the only negative reaction I've ever had to any treatments has been this one rescue - and Advocate just made him itchy.
Remember the whole autism / vaccine scare. Just because a dog has a fit after a medication does not mean the medication caused it.
And I'm a raw feeder too - have been for over 20yrs - so I see all the discussions online about flea and worm treatments. My own conclusion is that it is better & safer for my animals if I give the treatment.