c. 1900-1920 Purina traces its roots back to 1894, when founder
William H. Danforth began producing feed for various
farm animals under the name Purina Mills. The predominant brand for each animal was generally referred to as "Chow"; hence there was "Purina Horse Chow", "Purina
Dog Chow", "Purina Cat Chow", "Purina Rabbit Chow", "Purina Pig Chow", and even "Purina Monkey Chow". Later, in 1902, he merged with university professor
Webster Edgerly, founder of
Ralstonism, who was at the time producing breakfast cereals, to form the "Ralston Purina Company". Ralston Purina sold Purina Mills, the U.S. animal feed business, to
BP in 1986, while retaining the
pet food and international animal feed businesses. In 1993, the Sterling Group of Houston led a leveraged buyout of Purina Mills. In 1998, it was purchased by
Koch Industries, but a U.S.
bankruptcy court cancelled out all equity held by Koch to maintain the company's viability. Purina Mills filed for
Chapter 11 bankruptcy protection in 1999, and was purchased by Land O'Lakes in 2001. ==Licensing rights==