For doggie use, we purchased dandelion root powder off of Etsy. The dog's owner is tucking it into a small ball of ground meat. We are using 1/2 tsp powder twice a day for a 40 lb dog with cancer.
When I make this for human use, I make dandelion root extract (tincture), because that is what the nih.gov studies have been using with success. For this I use washed and chopped up dandelion root, and cover with a good vodka, like Wheatley's Vodka. Keep in a sealed jar in the pantry for at least a month, and then strain the vodka. Now you have medicine. For human use, I say start with 1/4 to 1/2 tsp of tincture, once or twice a day, depending on what you are taking it for. In cancer use, I would start with the 1/2 tsp twice a day. I also read in another study that it greatly compliments traditional cancer treatment for those people who choose to go that route.
I take it sometimes as an antiviral. It has a slightly bitter taste, so I sometimes add it to my coffee, and I sometimes just add it to a shot glass of water.
This medicine can also be used lower blood sugar, as replacement to a water pill (diuretic), slows blood clotting, rich in potassium, detoxing tonic, cholesterol management, and like Anne mentioned: anti-inflammatory and antioxidant. It also works to keep viruses from replicating, I had read about in a different nih.gov study. (Yes, this is what I do for fun. Read medical journals. Thrilling, I know. But a person can never have too much medical information. Doctors are expensive.)
Important Disclaimer: I am no doctor, but am told that this medicine can interact with diuretics, blood thinners, antiplatelets, lithium, antibiotics (quinolones), diabetes meds, blood pressure meds, medicines broken down by the liver like Cytochrome P450, and of course don't take if you are allergic to dandelions. If you do take any of the listed medicines, you'll have to discuss with your doctor. If you take dandelion, you must drink enough water to keep from becoming dehydrated due to the diuretic effect of dandelion.