In the United States, ferrets were relatively rare pets until the 1980s. Dr. Wendy Winstead, a veterinarian, sold ferrets to celebrities including Dick Smothers and David Carradine while making television appearances with ferrets in the 1980s, writing books and promoting them until her death in the 1990s from cancer. A government study by the California State Bird and Mammal Conservation Program found that by 1996, approximately 800,000 or so domestic ferrets were likely being kept as pets in the United States.