DE is used to keep bedding dry (thus odor free) as it is very absorbent. It also has insecticidal properties, as it dessicates insects and their eggs. Many put it in dry areas where their chickens dust bathe for this reason. Contrary to what some might say, I don't believe it can eradicate an existing lice or mite infestation, but it might help prevent one. Others say it has de-worming properties when ingested, but I can't see how this would be as it is completely de-activated when wet (it does not work by "poking holes" in the worms/insects as is often said, it works by dessicating/sucking out the moisture). Check with your local feed store, see if they have any other product that works like Stall Dry and contains DE, or maybe they can order it.
If you have free-roaming dogs in your area, you are probably OOL when it comes to free-ranging (that is my situation)--unless you can talk to ALL to owners, and convince them to keep their dogs in ALL the time. I can't get them to even keep in the dogs that harass neighborhood kids. Dogs are the worst predator IMO. Keep your chickens in a strong, well fortified run.