Happy, if I remember it well, was (once) the name of some dog (canned)food.
If the dogs felt happy eating it, I do not know. The thing with dogs is they simply swallow their food, do not really take the time to sniff and taste. A full bowl is gone within a few minutes time. That is how dogs eat and normal behaviour. They are also able to eat rotten food without getting sick.
Most dogs do not eat that way anylonger.
They are spoiled and I even once had a neighbour who was sitting on the floor next to her dog, feeding it with a fork, bite by bite, day in, day out. If dogs eat like that there are only two reasons for it.
One: the dog is ill.
Two: the dog is spoiled.
Most dogs (cats too) are spoiled.
The good thing about that is they have a good life. The bad thing about it is many are literally spoiled to death. Most dogs are overweighted, just like cats and overweight in animals is not different as in people. It causes exactly the same diseases and the only one you can blame for it is yourself.
Please stop overfeeding your pet. Stop feeding it what is not good for its health.
No matter what you think, many manufactured petfood is also bad. It is even proved that dogs who eat leftovers are more healthy and get older.
Ask yourself what kind of animal you have.
Is it a herbivore, a carnivore or omnivore? The fact your animal is a pet does not mean its digestion is different, has changed from its anchestors. It is not and it will never happen.
So if you are a vegetarian do not make a vegetarian out of your carnivores since that will not work. Take a goat or rabbit they eat the same food like you (although they do not take B12 as a supplement like you need to do.)
All the dogs I had and have were and are happy and healthy.
They also look young and never been ill. There was only one exception and the problems he had was the fault of his breeder.
This is my entry at the daily #5-minute-freewrite with the prompt happy. For more info see 
