Excerpted from The Dog Food Book, 5th Edition ©1999 Good Dog! Inc. All rights reserved. www.dogfoodbook.com

There are hundreds of choices. Wet food, dry food, semi-moist. High protein and high fat, medium protein and medium fat, high protein and medium fat, low protein and low fat. Super-Premium, Premium, Performance, Regular, Economy. High price or low.

What's a dog owner to do? How do you select the best dog food for your dog? This chapter will help you understand the differences between dog foods, and help you decide what your dog needs.

The Good Dog! dog food reviews can help, too. While we don't make specific recommendations, you can benefit from the experience of our dog food testers. But you have to make the ultimate decision. No one can make that decision for you -- not the pet store clerk, not the person who bred your dog, not your veterinarian.

The truth is, there are many good choices of dog food. Nearly everything on the market today will do at least an adequate job of feeding your dog. Some will work better than others, some have better quality ingredients than others.

We want you to choose a dog food that's best for your dog. Just as you can live fine on macaroni and cheese (plus some vitamins and minerals) for the rest of your life, your dog can live fine on most dog foods. But why settle for just fine?

Let's boil it down to a few basic rules, which we'll summarize here. We'll explain these concepts in greater depth later in the book:

This is the most important rule of all, and the most difficult to interpret. The reality is that your dog will do better on one food than on another. Your neighbor's dog (or your other dog) may not do as well on that food, but will do better on another brand.

That means you have to be the judge. You may have to try several different brands of food over the course of a year to determine which is the best for your dog.

Look for a food your dog enjoys eating. You'll want a food that is digestible, as indicated by a small to moderate stool volume. (Check a week after switching foods.) After a few weeks, look at the dog's coat to see if there is an improvement. The coat should be shiny and healthy looking. The dog's skin should be a healthy color, without any sores, itching or trouble spots. The dog should have a healthy look overall.

These are the primary areas we look at when testing dog food. It's also important to look at the quality of ingredients and the commitment of the manufacturer. You'll find tips on those subjects in "Secrets of the Dog Food Business," elsewhere in this book.

We're not going to bore you with a nutritional lecture. But we can give you the basics in just a few paragraphs. So don't skip this section!!

As with any animal or person, it takes carbohydrates, protein, fat, amino acids, vitamins and minerals to run the body. Carbohydrates, protein and fat supply the dog with energy. Fat is the main source of energy for the dog. It supplies twice as much energy as carbohydrates when digested. Protein is used for building and maintaining the body -- as long as there is enough energy supplied by the carbos and the fat intake. Otherwise, protein is diverted to supplying energy.

Carbohydrates, which usually come from plants, vary in digestibility. The more digestible, the more useful they are. Rice, corn and wheat are highly digestible carbohydrates.

There is a place in the diet for less digestible carbohydrates. We call the less digestible carbos fiber. Fiber is important in keeping the digestive system flowing properly. An excellent source of fiber is beet pulp. You'll often see it in dog foods, as it helps keep the intestines healthy.

Proteins are found in both plants and animals. In plants, protein is found mostly in actively growing leaves and in seeds such as corn kernels and wheat or soy grains.

Animal protein can be found throughout the body. It's the main constituent of bones, ligaments, hair, hooves, skin, organs and muscles. Some protein sources are more digestible than others. For instance, muscle meat is more digestible than ligaments.

Proteins are made up of amino acids. There are 22 of them, but 11 are not manufactured in sufficient quantity by the dog's body. These 11 are called essential amino acids, since it is essential they be added to the diet. Some proteins will supply more of one amino acid than another. That's why a mixture of protein sources is important.

Every pet food sold in the U.S. and Canada is labeled with certain nutritional information. This label is entitled the Guaranteed Analysis.

Looking at the Guaranteed Analysis, you will see several lines of information: Crude Protein, Crude Fat, Crude Fiber, and Moisture. Sometimes, ash, calcium and phosphorus are listed, too.

Let's look at each of these, and see what they tell you about the food.

Crude Protein usually runs between 14% for a Light food to 32% for a Performance food. The number given for crude protein is a minimum. So, at least that percent of the food will be crude protein.

The word crude indicates that this number is for both digestible and undigestible protein. What is digestible protein will vary depending upon the ingredients and their quality. That's why the crude protein figure is only a rough guide.

Likewise, crude fat is the minimum amount of fat contained in the diet, before the dog metabolizes the food. Crude fiber is the maximum amount of raw fiber in the food.

Moisture is the maximum amount of water in the food. Canned dog food usually contains around 75% moisture, while semi-moist foods contain 25% to 40%. Dry dog foods usually contain 10% to 12% water.

The amount of moisture in the food can become an important factor when comparing foods. To compare foods equally, you must adjust for the amount of moisture. A food with 22% protein and 12% moisture would have less protein per pound than a food with 22% protein from the same sources, and 10% moisture. The number you see in some manufacturers' literature for "dry matter basis" takes the moisture factor into account. Numbers shown on an "as fed" basis are not adjusted for moisture content.

The Guaranteed Analysis provides minimums and maximums. These are the guidelines which set the limits, but the actual numbers may vary. Quality of the ingredients may vary, too, depending on the season, the source, and the supplier. Under state regulations, the food must meet the minimums and maximums stated in the Analysis.

Many people think that a higher protein food is "better" than a lower protein food. This is not necessarily so. While Premium and Super-Premium foods do contain better quality, more digestible ingredients, a dog will still live well on a lower-protein food.

Most people tend to feed the same amount of a high-protein, high-fat food as they did a lower-protein, lower fat food. This results in overfeeding, which wastes money and causes your dog to get fat. Be careful to adjust your dog's intake to account for the food you give him.

The ingredients list on the package is an important source of information about the food. Read it!

Bear in mind that the ingredients are listed in descending order of predominance, by weight. The ingredient which weighs the most is listed first, the second heaviest ingredient is listed second, and so on. (Some petfood companies know that you know this, and play games to make their list look better. One game has to do with "real meat" as the first ingredient. Remember that meat has a lot of water in it, and water is heavy ...)

Read carefully, and learn about the ingredients.

Why would you want to feed a more expensive, high-protein, high-fat food?

The better quality, more expensive foods usually cost you less per feeding than inexpensive foods. You feed less of these highly digestible foods, and it costs you less in the long run. In our test, it cost an average of 24¢ a day to feed a 40 pound dog a Super-Premium food, while it cost 26¢ to feed a Premium food and 31¢ a day to feed an Economy brand. The dog would have to eat 3-1/2 times more of the Economy brand to get the same nutrition as the Super-Premium.

With the Super-Premium and Premium foods you pay less per day, and get a better quality food. It gets more expensive per day as you go down through the categories.

By spending more per bag, and feeding less -- as described in the suggested feeding instructions on the bag -- you can save money.

Some Premium foods make you think they're Super-Premiums. They're priced like Super-Premiums, but the ingredients list puts them back in the Premium category. Check carefully, and don't be misled by high prices!

Your dog needs to eat a food he likes. Most dogs do have preferences, and it's important to honor them. If your dog eats the food with vigor, he'll get all of the nutrition required.

The pet food industry calls tastiness "palatability." Taste is a function of the ingredients used, as well as the flavorings added. It's determined by test dogs who are allowed to choose one formulation compared to another. You can do your own palatability study by putting two brands in bowls side by side to see which your dog prefers.

Many manufacturers use poultry or beef digests to enhance the palatability of their foods. For example, poultry digest consists of chicken or turkey parts that have been broken down by using chemicals or enzymes, resulting in a powder or liquid. This is included in the dog food mixture during processing, or sprayed on at the end of the process along with vitamins. Dogs love the flavor.

For every food reviewed in our magazine, we assign a category. These categories are based primarily on quality of ingredients and the concentration of nutrients in the food. We also take into consideration the Guaranteed Analysis, metabolizable energy, digestibility and price per feeding. In addition, we look at how the foods perform in our own dogs.

Although the guidelines we use are for a dry, adult maintenance diet, there is plenty of variation within each category. Your dog may do just fine on any of the foods listed in each category.

Economy foods have a low price and use low-quality ingredients. The crude protein value averages 19% and the crude fat value averages 8%. You'll find these products at supermarkets, feed stores and discount stores.

Economy brands feature cereal grains such as corn, wheat and soy at the head of the ingredients list, followed by a meat source. Economy foods are low in digestibility, which means you must feed more to meet the dog's nutritional needs than any other category of food. So you actually spend more in the long run. The low digestibility also means there is a huge load of poop to pick up.

Economy brands are "complete and balanced" and meet the official standards. However, the standards are usually met by doing a laboratory analysis of the food, rather than the preferred method of a feeding trial -- feeding the food to dogs.

Economy brands are not our favorite choice.

Regular foods are moderately priced, and their ingredients reflect it. These products usually contain soy.

Regular foods have at least 19% crude protein and 8% crude fat. A typical ingredients list will feature cereal grains such as corn, wheat and soybean meal ahead of any meat source such as meat and bone meal.

You'll find the majority of Regular foods at the supermarket. While millions of dogs do well on these foods, we think your dog will do better with one of the next categories.

Premium foods are a good step up from the Economy and Regular categories. They usually represent a good value.

Some Premium foods contain soy, others do not. What these foods do have in common is that they are quite digestible and use decent protein sources. The Premium foods that do not contain soy have ingredients of the same quality as the Super-Premiums. The average crude protein level for a Premium will be 21%, and crude fat will average 10%. They're a good choice, offering good value for the price.

The ingredients list for a Premium food usually will have meat sources as the first or second ingredient, followed by cereal grains, and possibly soybeans.

A Premium food's ingredients might show meat and bone meal, brewers rice, and ground yellow corn, or it might start with ground corn and poultry by-product meal.

Super-Premium I foods have an average of 25% crude protein and 15% crude fat. A typical ingredients list might show chicken, chicken or poultry by-products, corn, and wheat as the top ingredients.

What separates Super-Premiums (and Performance) foods from all the rest is their high crude protein and fat content, along with the absence of soybeans. Manufacturers can get the high crude protein level by using high-quality meat sources and gluten meals instead of soybean meal to boost the protein content.

Super-Premium II category foods sport the same excellent ingredients, but are formulated to be lower in fat -- from 10% to 14% crude fat. Most Super-Premium II foods are made by the same companies which make the Super-Premium foods.

Beware of Premium dog foods masquerading as Super-Premiums. Some foods are priced high enough to be Super-Premiums, yet the ingredients tell the true story. You'll never find a Super-Premium in a can, either -- they just can't pack enough energy in with all that water.

Super-Premium brands are rare in supermarkets. Look for them at the pet store or feed store.

Performance foods are the heaviest-hitting foods on the market. They're designed for active dogs, such as those who hunt regularly or participate in high-energy activities like dog-sledding. Performance foods never contain soy, and will have an average of 30% crude protein and 20% crude fat. The ingredients will be similar to the Super-Premiums.

While we can help you make informed buying decisions, the ultimate test is how your dog does when fed the food. Try different foods, and be observant. Make informed choices, and stick with what works!

©1999 Good Dog! Magazine. All rights reserved. May not be reprinted or reposted without permission. Visit www.gooddogmagazine.com or call (800) 968-1738 to order The Dog Food Book 5th Edition.