Pet food 101: reading a label (Proceedings)


Pet food labels serve as marketing devices, as legal documents, and sources of limited nutritional information. Unfortunately, these purposes are often at odds as the current regulatory environment reflects the evolution of companion pet diets from livestock diets rather than from human foods.

Pet food labels serve as marketing devices, as legal documents, and sources of limited nutritional information. Unfortunately, these purposes are often at odds as the current regulatory environment reflects the evolution of companion pet diets from livestock diets rather than from human foods. While some nutritional information can certainly be ascertained from a pet food label, this information tends to be much less detailed and more difficult to interpret than human "Nutrition Facts" labels. It is important for veterinarians to understand what information is legally required to be on a label and how to use this information to help clients make informed decisions regarding pet foods.


Pet food labels are regulated both nationally and at the individual state level. Two main organizations are involved: the Food and Drug Administration (FDA) and the Association of American Feed Control Officials (AAFCO). The FDA regulates pet foods nationally through the Center for Veterinary Medicine (CVM). The Federal Food, Drug, and Cosmetic Act (FFDCA) requires that pet foods, like human foods, be "pure and wholesome, safe to eat, produced under sanitary conditions, contain no harmful substances, and be truthfully labeled".

The FDA has some basic requirements for pet food labels: proper identification of the product, net quantity (weight) statement, name and place of business of the manufacturer or distributor, and an ingredient list ordered from most to least, based on weight. The FDA is also responsible for evaluating product health claims on labels – i.e. hairball prevention, urinary tract care, etc. The FDA has enforcement power to pursue violations in labeling and manufacturing processes, including prohibiting the sale of certain products and even enforcing jail terms for individuals repeatedly found to be in violation.

AAFCO is not a governmental regulatory organization; however, its members are all state or federal government officials that meet to review the current knowledge and regulations on pet food and make recommendations. AAFCO committees may be advised by outside individuals from industry and academia. AAFCO is responsible for setting guidelines not just for dog and cat food, but for feeds for all domestic animals. It is important to keep this in mind as some of the information in their annual publication, especially some ingredient definitions, apply much more to livestock than to pets.

Most, but not all, states adopt AAFCO regulations as their own and enforce them. AAFCO itself has no enforcement power and also does not "approve" pet foods, despite this claim often being found in pet food marketing literature and lay publications. AAFCO publishes yearly guidelines which can be purchased online from their website. AAFCO publications include guidelines for pet food labels, ingredient definitions, tests of nutritional adequacy, additives, and recommended nutrient levels in diets for various life stages of cats and dogs.

Key elements of a pet food label (*required)

     • Product name* - there are strict rules for naming products. For example, "beef for dogs" must legally contain >95% beef on a dry matter (DM) basis and >70% as fed. "Beef dinner", "beef platter", and "beef entrée" require that beef be >25% total weight. "With beef" means that the product is at least 3% beef. "Beef flavor" generally means that there is less than 3% beef. Moisture may not exceed 78% unless the terms "in sauce", "in aspic" or "in gravy" appear in the product name.

     • Designator* - "dog food", "for cats" – states diet use

     • Manufacturer or distributor info* – all labels must include an address to contact the manufacturer or distributor. Although a telephone number, email address or website address are not required to be on the label, it is best to avoid companies that do not include at least one of these methods of contact as it is often impossible to get timely information by mail only. Beware of foods that just list the store as the manufacturer – big box stores and grocery stores (i.e. Safeway, Whole Foods, Trader Joe's, Wal Mart) do not make their own food. It can be very difficult to get any information on these diets by contacting the corporate office of the store that sells them and the stores are often unwilling to release information about the true manufacturer.

     • Guaranteed analysis* – only minimum protein, minimum fat, maximum fiber and maximum moisture must be included unless the manufacturer adds statements such as "now with omega-3s" or "with added taurine" to the packaging, in which case the amount of the specified ingredient must also be listed. The amounts listed are "as fed" amounts. These "crude" amounts may vary from the actual amounts in the food and cannot easily be used to compare two different diets without conversion of the values to standardized units (such as grams per 1000 kcal; Mcal).

     • Ingredient list* – ingredients must follow standard definitions (in AAFCO publication) and be listed in order of weight. Moisture is included in the weight, so high moisture foods (like meats and fresh vegetables) will be heavier than drier foods (grains, meat meals). Exact amounts are not included and cannot accurately be estimated from the ingredient list. Ingredients can also be split into component parts – rice can be listed separately as rice bran, brewer's rice, and rice flour and chicken could be listed as chicken liver, chicken meal and chicken fat. "Meat" or "meat by-product" can refer to goat, lamb, pork or beef. Ingredients lists are often subject to marketing whims and do not necessarily reflect the quality or nutritional adequacy of a diet. They may, however, reflect expense in the case of unusual (and unnecessary) ingredients such as quail eggs, pomegranate, and bison.

     • Feeding guidelines* – usually based on standard maintenance energy requirement (MER) equations with a safety margin. Animals should be fed to meet caloric and nutrient needs to maintain an ideal body condition, regardless of the feeding directions on the label. However, be aware of patients that are consuming less than 80% of the recommended amount for their weight as they may be consuming inadequate nutrients and probably should be fed a diet with a lower energy density.

     • Nutritional adequacy statement* – AKA "AAFCO statement". All pet foods marketed in states adopting AAFCO guidelines must have one of the following statements clearly printed on the bag:

          1. This product is intended for intermittent and supplemental feeding only

          2. Animal feeding tests using AAFCO procedures substantiate that Product X provides complete and balanced nutrition for [species, life stage]. (Life stages include maintenance, growth, gestation and lactation and all life stages)

          3. Product X provides complete and balanced nutrition for (species, life stage), and is comparable in nutritional adequacy to a product with has been substantiated using AAFCO feeding tests.

          4. Product X is formulated to meet AAFCO nutrient profiles for [species, life stage]

Diets that are "formulated to meet" do not have to be fed to any animals before being put on the market. Additionally, diets that fail AAFCO feeding trials could technically still be marketed under a "formulated to meet" statement. Feeding trial protocols are detailed in the AAFCO guidelines and specify that a certain number of animals are fed the diet for a set time period, that data is collected on weight, blood values, reproductive performance and growth (growth or all life stages), and that no detrimental effects are noted. Feeding trials may also used by manufacturers to collect digestibility data for foods although this information is not required. While most diets that have passed feeding trials are also "formulated to meet", they do not have to be. For example, Hill's Prescription Diet canine k/d has passed feeding trials for adult maintenance but is too low in protein and phosphorus to carry a "formulated to meet AAFCO" statement.

     • Net Weight* - the amount of food in the bag. Keep in mind that the caloric density is more important than the weight of the food when determining feeding costs as foods can vary in caloric density (35 pounds of one food may have the same calories as 18 pounds of another).

     • Calorie content – not required unless a diet is marketed as "lower calorie" or "light", if present, it must be in kcal per kg, often also presented in kcal per cup.

Comparing pet food nutrient distributions using the label

As previously discussed, the information included in the guaranteed analysis (GA) is not always very useful when it comes to making decisions about which diet may be appropriate for which patient. It is best of obtain a typical analysis from the manufacturer if at all possible. At the very least, it is necessary to convert the GA values to values that are standardized for fiber, moisture and caloric density to directly compare diets.

While some nutritionists use dry matter (DM) values, which overcome differences in moisture, to compare foods, DM does not take into account differences in fiber and caloric density between foods. It is more accurate to compare pet foods on a metabolizable energy (ME) basis. ME refers to the percentage of the calories of a diet that come from protein, fat and carbohydrates, taking into account both fiber and moisture. There are several references that show detailed methods [see 'Further information', below] for calculating ME for pet foods based on the GA or typical analysis (obtained from manufacturer, actual amounts rather than min and max) as well as online calculators such as the one at: To calculate the ME most accurately, the ash content of the diet is required. This value may or may not be listed on the bag and can be estimated if not known (diets range from 2-15% ash, diets higher in by-products, bone and cartilage will be higher in ash, most diets are probably between 2 and 5% ash) and the manufacturer cannot be contacted.

Nutrients other than protein, fat and carbohydrates can be compared between diets by expressing them on an energy basis – i.e. grams per Mcal (1000 kcal). (Protein, fat and carbohydrate concentrations can also be expressed this way, but it is less intuitive to clients and technical staff). These units take into account the fact that nutrient requirements are related to body size and that animals of a certain size are expected to consume a similar amount of calories. There is concern that an animal that needs substantially less calories than average for its size may thus become nutrient deficient. For this reason, diets designed for animals with lower energy requirements should contain higher concentrations of nutrients per calorie to compensate for the lower caloric intake. Likewise, high energy diets should contain comparably lower concentrations of nutrients per calorie to avoid excesses.

For example, two dogs of similar size, age and health status require the same amount of calcium, despite the fact that they may consume quite different caloric intakes to maintain an ideal body weight. If both dogs are fed the same diet that contains 2 g calcium per Mcal, one dog may consume 2 grams of calcium daily while the other, who eats less, consumes 1.5 grams. Depending on the nutrient, this difference may or may not be a problem.

Evaluating pet foods


     • Is appropriate contact information listed for the manufacturer – i.e. phone number or web address? It can be quite difficult to obtain answers to simple questions such as caloric density or support in the event of problems with the diet without a phone number or email address. Labels that provide only a mailing address or list the store name as the manufacturer should be avoided.

     • Nutritional adequacy statement – feeding trials are preferred over "formulated to meet" statements, particularly from newer or smaller companies that are less experienced and when feeding growing animals. Foods designed for all life stages, regardless of whether feeding trials have been performed, may not be appropriate for large breed puppies – it is often better to stick with a diet specifically marketed for large breed puppies that has passed AAFCO feeding trials for growth.

     • Ingredient list – does the patient have any known allergies or intolerances to certain ingredients? Is the company using unnecessarily expensive or exotic ingredients as a marketing ploy?

     • "Quality" descriptors – although commonly used, the terms "premium", "super premium", "ultra premium", and "gourmet" have no legal meaning and can be used by any manufacturer without any burden of proof

     • Health claims – all health claims on diets must be evaluated by the FDA. However, it is not uncommon to see unsubstantiated health claims on labels and in marketing materials. If a health claim seems questionable, call the company and ask for written documentation of the claim (i.e. peer-reviewed publications).

Marketing materials

Beware of:

     • Unverifiable claims – "prevents cancer", "takes years off your dog", "increases energy and vitality"

     • Testimonials in lieu of data – ask for documentation of any claims made, remembering that in evidence-based medicine, testimonials mean little. However, testimonials are cheap and do not require any expenditure of time or expense on the company's part, so they are very popular.

     • Inaccurate or misleading nutritional information – i.e. incorrect definition of by-products or other ingredients, misspellings, and propagation of myths such as: grains cause allergies or are "fillers", high fat diets cause heart disease in dogs, flax is good source of omega-3 fatty acids for cats, etc.

Other factors

     • Knowledge of employees when you call on the phone – can they provide requested information in a timely manner?

     • Experience of people formulating diets. Anyone can be taught to use ration-balancing software, but it takes experience to know that some ingredients are more bioavailable than others, that various nutrients interact with each other and which nutrients are altered by cooking. Ideally, choose a company that employs veterinarians with advanced training (PhD) in nutrition or board certified veterinary nutritionists, especially for diets designed to help manage health problems. The average veterinarian is often not qualified to formulate a pet diet.

     • Support of independent research and publication of findings in peer-reviewed literature – there is a lot we still need to learn regarding ideal nutrition for our pets and responsible companies are looking to contribute to the knowledge base and constantly strive to produce better diets rather than just claiming that their diets are the best available without providing documentation.

     • Quality control – do they compare their recipe or an analysis of the finished product to the AAFCO profiles? Do they test every batch of raw ingredients? How do they substantiate their sell-by dates?

Further information

Dzanis, D. A. (2008). "Understanding Regulations Affecting Pet Foods." Topics in Companion Animal Medicine 23(3): 117-120.

Zicker, S. C. (2008). "Evaluating Pet Foods: How Confident Are You When You Recommend a Commercial Pet Food?" Topics in Companion Animal Medicine 23(3): 121-126.

Hand, M. S., C. D. Thatcher, et al., Eds. (2010). Small Animal Clinical Nutrition, 5th Edition. Topeka, KS, Mark Morris Institute.

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