According to the Huffington Post, UGG boots are made from the wool of Merino sheep. UGG Australia states that its company only uses soft, twin-face sheepskin. When sourcing its trademark sheepskin, the company looks for uniformity and flawless, fine-grained textures; the wool must be evenly thick across the entire piece.
UGG maintains that it does not use sheepskin unless it is a byproduct of the meat industry. The activist group PETA argues that UGG boots are made from the sheepskin of abused Merino sheep. Additionally, the online magazine Buzzfeed states that fake UGG boots are made from the pelts of raccoon dogs.