My dogs are raw fed so they do in fact get blood tested and fecals done. Always clean. I personally take studies with a grain of salt because if it's working for some, then the studies are not 100%. There are a lot of people that use DE as a preventative--maybe doing some studies on those would prove more beneficial. The chances of that happening are slim--just like studies on raw diets for dogs versus kibble. A lot of people stand to lose a lot if money if those facts ever came out. There are small studies here and there in favor of DE with worms. You would have to really look, not easy to find *CLINICAL OBSERVATIONS OF FEEDING CODEX FOOD GRADE DIATOMACEOUS EARTH TO DOGS, O.C. Collins, DVM, Midland Animal Clinic And Hospital, Midland, TX: "In clinical observations of feeding dogs over 35 lbs. 1 tbsp./day and under 35 lbs. 1 tsp./day of DE, within seven days all ova disappeared from stools. DE controlled Ascardis (Toxacara canids), Hookworms (Anclyostoma caninum), and Whipworms (Trichuris vulipis)."