Pet Food Put in Garbage Cart Do Not Compost Outside Pet food may contain animal protein, which can attract wild animals to an outdoor compost. Only compost pet food outdoors if it is vegetarian, or if you have a specialized composting system designed to handle animal products. Otherwise, put pet food in the trash. Ways to Reuse Give to a Friend or Pet Food Bank Give your unused pet food to a friend with a pet or donate it to a pet food bank. Did You Know? Pet Food Has a Carbon Footprint U.S. cats and dogs account for almost 30 percent of the meat industry’s pollution. Meat production has a huge environmental impact. Methane from cows, fossil fuels for transport and water used on ranches are all contributing factors. Read more from UCLA.