In my work for a dog food company, I have seen test results from various companies which would shock you. In a lot of cases, what is written on the bag is not what's in the bag!!!
Protein levels can vary by up to 5%, whereas normally only plus or minus 2% would be acceptable. Almost all of the puppy feeds on the market for example, have an inadequate calcium:phosphorous ratio (2:1 is optimal for good bone development).
There are even so-called dried puppy foods that contain 12% protein. A puppy needs 27% protein and around 10% Oil in a dried diet. Most puppies will require this until they are 6 to 10 months of age. Then they should be changed down gradually to a 20% Protein diet with around 8% oil.
Most canned foods were lacking in essential amino acids, plus the fact that they are a waste of money and not good for a dogs teeth. Canned foods consist of 85% to 90% water. Water makes the can heavy and the dog owner is really buying very expensive water!!! Dried foods contain under 10% water. Most of them are extruded, which means that the feeds is more digestible and acceptable to the animal's digestive system. Extruded dried dog foods are generally quite hard and are therefore good for the teeth. Canned foods can also lead to the build up of tartar on the teeth.
Dried food should really only be soaked for very fussy dogs, old dogs or puppies. The reason for this is that most of the little pellets or biscuits are coated with a layer of hydrolysate or fat, which gives your dog a good coat and also supplies the amino acids. With all dried dogfoods, give the dog plenty of water.
If you are feeding a good diet you will not need to feed vitamin supplements. The only supplements I give are herbal ones, which basically keep the coat free of insects (garlic is good for this, it also keeps worms at bay!!). The importance of nutrition really cannot be underestimated. You are what you eat. If we humans were being fed purely on canned foods, we wouldn't look that wonderful either and we'd be suffering from all types of diseases. A correct diet can prevent all types of problems and save in the long run on vets bills etc. The wrong diet can cause so many problems. Approximately 80% of canine skin problems are caused by bad diet. Bone malformation (irreversible) is caused by insufficient protein supply in puppies' diets.
On a finishing note, we must really include our dogs in our dietary planning. Too many people claim to be "too busy" to go to a pet store to buy proper food for their animals. If you buy a dog, you take on a responsibility for the dog"s life and wellbeing. Feeding the animal wrongly is a form of neglect. Surely the shiny coat and eyes of a healthy wellfed dog is thanks enough or reason enough to buy the correct food.