Pet food is big business — U.S. sales last year in excess of $20 billion kind of big — and there are dozens of companies all trying to get you to spend your money on their product.

They all claim to make the best food for your pet so how do you, the average pet owner and consumer, make a decision about what to buy?

If you are like most pet owners you want to provide your dog or cat with the best food you can. You probably ask friends, breeders, and pet store employees, and you look at the ingredients list on the bags of food. You may also probably look on the internet for information and you review the websites of the manufacturers for information. Sometimes you might even ask your veterinarian for nutritional advice.

Here is some information and advice that, hopefully, will help you make better choices:

• Remember that the purpose of marketing is to generate maximum profits. Marketing is free speech and the information that appears in TV ads, websites, and other marketing materials may actually be false or even illegal in terms of ingredient definitions. This is especially common when terms like “holistic,” “natural” and “organic” are used because marketers know that consumers are keyed in to these words.

• The labeling information that is put on the back of a bag of food has legal requirements based on federal and state regulations. The American Association of Feed Control Officials publishes guidelines and ingredient definitions, but it does not endorse or approve foods, and pet food manufacturers are not required to follow them.

• The most important rule in marketing is repetition. If you tell a consumer often enough that something is bad then consumers will come to believe that it must be true. Or, more subtly, a pet food maker will put a phrase such as “no soy” or “grain-free” on the front of their product, making the consumer wonder, “what’s wrong with soy or grain?”

There is no nutritional evidence to show that soy causes any problems and grain allergies are quite rare. A variation of this strategy is the tactic of vilifying ingredients in a competitor’s food in TV ads, even though there is no nutritional evidence to support the claim.

• Marketing is aimed at our emotions first and our logic second. The emotion pet food makers try to evoke most is guilt and that by not buying their product you are guilty of not doing the best for your pet. This kind of marketing is powerful.

Remember, commercial pet food diets, regardless of who makes them, are all processed and cooked in a similar fashion. The big differences are in the quality of the ingredients used and how well they control the manufacturing process from raw ingredient sourcing to the finished product. You should consider buying from companies that control all aspects of the development and manufacturing; companies that are investing in research that promotes veterinary nutrition and medicine to treat disease and improve the health of our pets through diets.

• By contrast, many of the currently popular brands of pet foods simply purchase a recipe and out-source the development and manufacturing to a third party, which returns the finished product to them to sell. The potential hazards of this were seen earlier this year when a single company that manufactures pet foods for over 30 major brands had eight major recalls related to Salmonella contamination. Besides the many pets that were affected, 43 people were hospitalized for treatment after handling the contaminated products.

So, where do you go to find out what pet food companies you should trust? Consider starting with your veterinarian — they can be your best resource to help you separate nutritional facts from marketing myths.

Dr. Kiel is the U.S. Army veterinarian currently supporting NAS Whidbey Island and Naval Station Everett. Please send questions or comments to Dr. Kiel at joseph.kiel@navy.mil.