Yes, I have used it for years around the house and barn. Make sure you are using the DE for agricultural use and not the DE for pools. It is a wonderful product and is definitely less expensive than other products.
I have some stuff in half gallon buckets called WRM CLEAR that is a homeopathic type wormer that basically Diatmaceous Earth is the main ingredient and it is supposed to be used as a wormer as well that is effective for Dogs Goats, Horses, Cattle as well. I have not had it long enough to know how well it works as such, but it is a powder form that you can either sprinkle over the feed or mix it with water and suck it up with a syringe and give orally if you have a picky eater. Has anyone else had any experience with this product??
A LOT of people use it for their chickens. And they say too, buy the agricultural stuff. There is talk about it all the time on the forums on www.backyardchickens.com. There is a search engine there where you can search the posts for DE. LOTS of info there, and links on where to get it. I plan on getting it myself!
I use it around the foundation of our house to discourage creepy crawlies, and inside the house in all those "dark corners" and on animal beds when we have flea troubles as we did this past year. (We still had to use Advantage on the animals, but I think it helped to keep the fleas from re-populating.) It is great for killing caterpillars before they denude your garden plants, which reminds me I have to dust my orange azalea...
As others have said, make sure you get the agricultural (not pool) type, and also wear a mask if you're spreading it around. It's a very fine powder, not toxic but probably not good to breathe in anyway.
I've read online about using it for a wormer, but haven't tried it myself on our animals.
I have used it for a year now and I have had great results. It also helps if you sprinkle it on your manure pile/ compost. Keep the flies down and works to get rid of the beatles. The issue is they have to come in contact.
I put in on the horses, just a light dusting, a few times a week. If it rains they need it again. A light dusting works well. But try not to let them breath it in, I have heard thats not good. I have not had an issue and I am not sure why. We also use it on our dogs and pigs. I need to get it on the chickens and ducks also!
I still have fly and horse fly issues, but not nearly as bad.