I currently use DE to dry my run after a rain, but that's it. I appreciate your honesty in that your vets did not worm your dog. Why didnt they if they finally suspected worms? My DW has been a vet tech for over 25 years and never heard of DE, much less using/feeding it to dogs and/or cats. All the vets that she's worked with have used chemicals to deworm dogs and cats. I've had chickens for years and was caught up in the "miracle" hype too. I religiously put it in their feed, til I visually saw roundworms in their poop and they were alive. All the symptoms were there too, just like your dog...lethargy etc..., and like a dummy, I ignored them. Something that DE was supposed to prevent/kill, but failed. Many others on here have stated the same thing and I've even posted a couple of their quotes. One dose of wazine, and 12 hours later my hens were bawking and sqawking and scratching around like a chicken should. There are many BYC'ers here that concur that DE is good for what it does, but also concur what it doesnt do, including worming. I have no reason to lie nor deceive, just experiences that I have personally dealt with in raising chickens. BTW I've owned quite a few dogs myself from Terriers to English Bulldogs and vets always gave them injections or pills to treat various types of worms when they had them. I'm glad you realize that chemicals have their use. Next time, tell your vet(s) to do their job and properly worm your dogs...you're paying for it anyway $$$. Good luck.