One of the first things you notice about a dog is the condition of his skin & coat. Certain skin conditions will require medical intervention as well as a change in diet, so please consult your Vet if you suspect there's something more serious going on with your pet's skin condition. However, all dogs can benefit from a healthier diet which plays a significant role in the maintenance of a top-notch coat!
If I were to choose what to feed my dog if I was focusing on skin & coat condition, I would mostly look at the amount of two nutrients.
Research shows that around 25-30% of the protein a dog takes in goes towards the maintenance of her coat. At first this statistic may seem excessive, but when you consider that the skin is the largest organ in a dog's body and is composed 95% of protein - it's no surprise. A deterioration in coat condition is only of the first signs of a dog deficient in protein.
Dry Dog Food designed for coat health should contain at least 21% protein - although this is a minimum and even higher protein levels are often better for your dog's health in general. After the protein content you should look at the ingredients list. An animal-based protein such as chicken or lamb matches your dog's needs generally far better than plant-based protein, however some dogs thrive on carefully-formulated vegetarian diets.
Fats, particularly fatty acids are also vital for the maintenance of a healthy coat. A diet that provides enough fat content as well as the correct balance of Omega 3 & 6 fatty acids will not only moisturise the skin from the inside out and reduce the risk of inflammation, but it can actually help prevent infection.
For Dry Dog Foods, a fat content between 10-20% is recommended for optimal coat care. Most manufacturers will not give a breakdown of fatty acids on their ingredients list, however ingredients such as Salmon or Flaxseed Oil are good indicators that the food contains a healthy amount of Omega 3 & 6.
Finally, one should also pay attention to the micronutrient profile of a food. With regards to skin & coat care, it should contain Vitamins A & E, as well as Zinc, Copper, Iodine and Manganese - all of these help control skin inflammation as well as grow new skin cells properly.
After following this advice, you should see a noticeable difference in the quality of your dog's coat within 1-2 months. However as always, should you feel that there is something more serious behind your pet's deteriorated condition, always consult your Vet.