If your pet dog has large, smelly stool, is gaseous, burps often, sheds constantly, is prone to ear and skin infections, has either no energy or is hyperactive and if his immune system is weak, something may be wrong with your pet's diet. Although any or a combination of these symptoms may occur occasionally, having them recur often is a cause for concern and reviewing your pet's diet is one of the first things you should look into.

First of all, your dog needs 45 nutrients to function properly. Major groups for these nutrients are protein, carbohydrates, fat, vitamins and minerals, as well as water. These nutrients have to be in the right amounts so that they are properly digested and absorbed by the body.

Remember that your dog, or any dog for that matter, is a carnivore, meaning his body mainly uses meat. That also means that vegetables and grains are not supposed to have a major contribution to your pet's diet.

On dog food packages how much protein is in the food is indicated. But finding out how much protein is in the food is not as important as knowing what source the protein came from.

Dog food makers have a wide choice of protein sources to choose from. Aside from meats (beef, chicken, lamb, etc.), plants and grains like corn, wheat and soy are used as sources.

To find out what sources have been used most in the package you're buying, look at the ingredients list. By law, the largest amount of ingredient used is listed first and others follow in decreasing amounts. You should see 3 meat sources on the first 5 items mentioned. Any less than that and you may not be giving your dog the proper protein for his diet.

Your dog will also need carbohydrates primarily for energy. But unlike their masters, dogs do not need a lot of carbohydrates to be healthy. A diet high in protein and low in carbohydrates is ideal for your pet.

Since dogs are meat-eaters, diets high in carbohydrates will take a long time for your pet to digest, not to mention resulting to large and smelly stool and gas. The gums can also grow sore due to excessive chewing and his breath can develop a bad smell. So only use a small amount of a carbohydrate source (such as grains) in your pet's diet.

Two kinds of fat exist. One is saturated (animal fat) and the other is polyunsaturated (vegetable fat). Your dog will need both and taken together supply essential fatty acids (EFA) needed to maintain good health.

Not enough fat in the diet can cause low energy levels, heart problems and dry skin. However, too much fat can cause obesity. Tumors and cancers can also develop. In reading the label, look for a product that has a good balance between animal and vegetable fat in it.

Vitamins are necessary to release nutrients from the food that the body can use. There are two types of vitamins: water-soluble vitamins and fat-soluble vitamins. Both types are needed by your dog. Vitamins B and C are water-soluble. Too much of these will not harm the body much since it is urinated out in 4 to 8 hours. This is the reason they need to be in each meal. Vitamins A, D, E and K are fat-soluble. They are stored in fatty tissues of the body and the liver.

It is important to remember that vitamins are easily lost in the making of manufactured dog food. And they break down as soon as you open the package and expose the food to light and air. Vitamins B and C are particularly sensitive.