You shouldn't have to buy ti online. I bet you can find it in a drugstore, hardware or pet store. It's not expensive either.
Here is a quote from the History page on the website:
"It all started in 1899, after John L. Norris bought the formula for Bag Balm from its original creator in the little town of Wells River, Vermont. The salve was created to soften cow udders, and it worked extremely well."
So... it has been tested on animals! Hah!
I've used it on my animals also - just cats and dogs. I don't have cows or horses.