National Mutt Day, also known as National Mixed Breed Dog Day, is observed in the United States on December 2 and July 31. Initiated by Colleen Paige, an animal behaviorist and pet lifestyle expert, this day aims to celebrate mixed breed dogs, educate the public about their unique characteristics, and encourage the adoption of these animals from shelters. Approximately 80% of dogs in American shelters are mixed breeds, which often face lower adoption rates compared to purebred dogs. The day highlights the benefits of mutts, including their generally better health and longevity. Celebrations typically involve adopting a mixed breed dog, and for those unable to adopt, donating money, food, or supplies to local animal shelters is encouraged.