As stated on their website:
Does your company test on animals or contain animal ingredients?
Please feel at ease when using Buxom Cosmetics products as we do not test on animals. We also do not work with any manufacturers that do animal testing. Buxom Cosmetics natural haired brushes are made of Goat and Pony. Please note that no animals are harmed in the process of making our brushes. For our customers who chose not to use animal haired brushes we do offer a variety of high end synthetic brushes.