If you use Heartgard, Interceptor, Sentinel, or ivermectin for heartworm prevention, they control most intestinal parasites. A good flea preventative like TopSpot or Advantage will keep out the tapeworms. So most dogs don't need additional intestinal parasite control. If you are worried, have a fecal sample analyzed every 6 months and treat as needed. My Aleksander is almost 10 years old, always on Interceptor, gets a fecal once a year, and has never had problems, despite his snacking.

Muenster (sp?) Milling makes organic pet food, & I think they include DE in their products.

A local organic radio program, The Natural Way, on 820 am radio on Sunday mornings, advocates adding DE to pets' diets at the rate of 1% by volume.

Do NOT use DE for swimming pool filters! You want the stuff sold for organic gardening. The pool filter stuff has been heat-treated to make it a harder, sharper, and a better filter, and it floats in the air and may irritate your lungs. (Dont' get hysterical - like many things, it takes repeated exposure to *maybe* develop a reaction. I load DE in my pool filter about 5 times per year, and simply use a decent dust mask. Chill.)

I was not able to find any reliable double-blind studies so I have no opinion if DE is effective or not.

Here are two sites that list positive first-hand experience with DE as a de-wormer AND have done at least some minimal studies to back it up. The DE seems to be at least as effective as the chemical de-wormers for some parasites.

DE used on large birds (ostrich and others)

http://www.oe1.com/index3.htm

DE reportedly used on sheep (search the page for Fossil Flour)

http://www.the-coop.org/wwwboard/discus/messages/5052/59.html

There was great evidence that Fossil Flour had little effect on Tape worm.It is however very effective against Large Ascarid and other Micro skinned internal parisites.Tougher skinned and segmented worms are able to survive through Diatomaceous attack.Fossil Flour actually works by nicking the membrane of worms and leaving them exposed to digestive juices which convert them to a protien source for the host.

The page below for dogs/wolves states the DE should be administered for at least 60-90 days to be effective and break the parasite cycle.

Here is a link that might be useful: wolf creek ranch DE use

A perfect wormer and also a good site to be assisted with about pet health issues is www.cosmic1.net.

Here is a link that might be useful: Pet health: Wormer

Yes, people took DE in a glass of water to control intestinal parasites, and it is not as effective as the products out nowadays which target specific parasites, and get rid of the problem in no time. Measuretwice is absolutely correct, never use DE which is formulated for pools for anything but pools. It contains alot more chemicals which are not good for anyone or anything but pools. If you get DE, ask your local nurseryman for a source. I know you can get it online from some of these organic places. Be careful when dealing with it, you dont want to inhale any of it. Make certain your animals dont inhale it either. Bags of DE are sold in pretty big sizes, you probably dont want to just keep a bunch lying around. Good luck, I hope you find what you are looking for.