Sometimes when puppies in a litter have to compete for food, they will take advantage of the presence of food to eat as quickly as possible to survive.  This will sometimes happen when the litter of pups is particularly large and they don't have easy access to the mother's milk.  You might be able to slow down the dog's eating by only giving small quantities often.  Soaking the food in water or gravy may prevent the dog from choking or vomiting the quickly inhaled food.