The food grade Diatomaceous Earth can be taken internally both by animals and humans. It has many uses that can be found by doing a google search. It can be used the same as borax in some of the other postings.
------------------------------------------------
I agree, the DE sure does help with the fleas. I put some commercial stuff on my cats last year and they both got sick..one kept falling off a stool that he'd previously sat on to watch birds, the other one started walking sideways. My sister's two cats, also de-fleaed with that 50 dollars worth of poisons, started throwing up and acting strange. Now I even put some of the Diatomaceous Earth in canned cat food for one, and have to smash some on Fussy Freddy's front paws so she will clean it off.
The indoor/outdoor Dobies we had for so many years we put the DE in meat balls and tossed it to them, and put vinegar in their water. Come to think of it, don't remember much problems with fleas. The only time one son complained about itchy bumps from the dog who slept with him (not allowed, but it did anyway) the kid had Chicken Pox and not flea bites.