Proper nutrition is the fundamental basis for every aspect of your dog's life.
It affects their health and longevity by offering an essential balance of proteins, fats, complex carbs and nutrients and minerals their bodies need for growth, repair. Also, the maintenance of a sound canine immune system.
Canine nutrition is a complex and integral part of your dog's ability to think clearly, lower stress levels and produce a calmer behavior.
Thinking takes a lot of energy. Dog training programs, expend tremendous amounts of mental energy focusing on the tasks presented to them. If your dog starts with minimal nutrition, they become lethargic, edgy or hyper active when asked to perform the simplest of tasks. They cannot focus and loss concentration after a short period of time or become confused. If the dog is continually asked to do something they cannot comprehend, confusion can lead to an aggressive form of acting out.
In training dogs, the first thing I look at is the dog's diet! I work from the inside out. Training becomes ineffective if the underlying cause for the behavior is not changed.
A lesser known fact is that to feed your dog only meat (with no bones and no cereals or other carbohydrate source) can cause severe deficiencies: your dog is likely to become lethargic, sick, and even death has been known to occur from an all meat diet. But what about dogs in the wild, I hear you ask? Isn't meat a dog's natural diet? Isn't that what you just said, Brigitte? Well, yes and no: in the wild dogs eat the whole of their prey, not simply muscle meat - they thus obtain vegetable matter from the digestive tract of their prey, and calcium from the bones. As well, wild dogs occasionally, but routinely, add to their diet with plants, fruit and berries.
Most dogs relish some raw fruit and vegetables in their diet, so long as that's what they're used to. A dog who has been fed commercially prepared dog food all of its life won't be used to the taste of fresh food, so may well turn up his/her nose if you introduce such healthy food later in life. But persevere - try hand feeding pieces of carrot or apple to begin with. And if your dog is still very young, even better. Start as you mean to go on and feed him/her some raw fruit and vegetables from time to time. Your dog's health will benefit!