I want to give my dog chanca piedra; does any know about this herb?

Dogs cannot properly utilize anything plant based. You'd be wasting your money and taxing his pancreas. Dogs do not produce the necessary enzymes to break down the cellulose on the cells of all plant matter. Their pancreas must work harder to produce more amylase to attempt to break it down. It then goes out pretty much unchanged from when it went in and it's benefits are left in a pile of poo. It's an irritant to his system just like grass, grains, carbohydrates, starches, sodium, sugars, etc. You are better off feeding a raw diet so his liver doesn't have to process all the garbage that's in commercial dog foods.

http://rawfeddogs.org/rawguide.html

It is interesting to read so many warn of the dangers of feeding onion, garlic and grapes since I have been feeding my dogs these for more than 20 years and so far not a single one has dropped dead from any kind of poisoning. And sorry, I beg to differ about the "old wive's tale" as it is a proven fact that the sulpher in garlic and onion IS a poison and WILL kill parasites. The question is the quantity fed to your dog. As part of a raw natural diet, these foods along with just about any other vegetables and fruit are indeed most beneficial to dogs. Even veterinarians around the world, especially in countries like Australia where there is a strong move toward natural as opposed to commercial foods ( look at how many dogs and cats are dying right now in the USA as a direct result of having consumed commercial foods that are now being recalled) are reporting way fewer health problems such as pancreatic disease, kidney failure, skin allergies and protein losing enteropathy. For my part, my dogs have never been healthier with my Bernese living to 13+ years and a Leonbrger who is about to celebrate her 15th birthday.

Milk thistle has actually proved very effective for liver disease in dogs. Why not try it?

I'm wondering about the extract rather than the whole herb?