Duffield is also known for his philanthropic activities on behalf of animals. In 1994, Duffield and his wife, Cheryl, established Maddie's Fund named after Maddie, a Miniature Schnauzer who was the Duffields' source of unconditional love and friendship for ten years. Maddie died of cancer and Duffield acted on his earlier promise to his pet, "If we ever make some money, I promise we will give it back to you and your kind so others can be as happy as we are today."
The Duffields have endowed Maddie's Fund with more than $300 million, and have spent more than $153 million through fiscal year 2013-2014 to save the lives of dogs and cats. The organization believes that the Duffields have given more of their personal wealth to the animal welfare cause than any other individuals.
