Everybody's loves to eat! Your dog is no exception. Eating too quickly is more common with puppies as their food is very small and their energy level is a little over the brim.
Eating too quickly is not only hard on your dog's digestive tract, but it can also lead to vomiting. If they vomit their food, they are losing nutrients (although most dogs will eat it again after the fact, unpleasant but true).
To slow down your dog, place a large rock in their bowl. Please be sure that this rock is large enough that there is no way they can swallow. I'd say at least the size of your fist, maybe slighly smaller. Place the rock in the middle of their food bowl and pour their food around the outside edge of the rock. Specialty bowls can also be found with a large object built into the middle of the bowl.
Chances are your pet will not be amused with this new feeding method. Don't worry, they love their food and they will get used to it very quickly. The sound of them chewing their food will be worth the short argument.
This forces your dog to try a little harder to get each bite. It might not slow them down a lot, but it should be enough.
If this doesn't work, you can try giving your dog small amounts of food at a time. Ask your dog to sit. Wait until they calm down a little, and pour 1/3 of their food in the bowl. Wait until they finish that, ask them to sit again and repeat until their food is gone.