If your dog just ate a bite without toxic ingredients like garlic and onions, he should be fine. However, most pizza recipes include a sauce and various toppings like garlic, onions, pepperoni, excess oil, and salt, which may cause harm to your dog. The wheat flour, yeast, salt, sugar, and oil can be dangerous, especially for dogs with wheat allergies or obesity. Pepperoni contains high amounts of sodium, fats, and calories that can result in digestive issues and pancreatitis. Other ingredients like onion and garlic can damage your dog’s red blood cells causing anemia.