Many medicines were derived originally from somewhere in nature - a fungus, a plant, a hormone, a mineral. We've synthesized some and fiddled around until we found a dosage that worked for a majority.
The reason most of you have most of your teeth is because someone figured out that the mineral fluoride, when added to your drinking water, keeps your teeth from rotting out of your skull. Somebody figured out that iodine keeps you from getting goiters (ever wonder what "iodized" salt meant?), and Vitamin C keeps you from getting Scurvy.
Unfortunately, that's the thing with animals. They can't tell us why they hurt, or what's wrong, so we've got to do a little more experimentation. Sometimes a medicine can help, a change of diet, more exercise, massage, etc.
Because herbs and supplements aren't regulated, it can be easy to fall into the Snake Oil pit. I'm finding now that there are people trying to solve everything with essential oils - I did aromatherapy before it was cool as a massage therapist, so I also know that certain oils can burn you, poison you, irritate your lungs, cause miscarriages, and even kill your pets. That same lovely scent in cedar and pine oil can slowly cause your kidneys and liver to fail if you absorb enough of it through your skin. But if used correctly, and in the right ways, essential oils can be helpful in some situations, too.
My point in all this is that we've got to be skeptical when somebody comes along promising us the moon and the stars in a bottle, for just a few dollars! We need to document problems, take pictures, ask many many questions, know basic science, and have a critical eye when someone's trying to sell you something.