Understanding Pet Food Labels

Pet food labels are legal documents in the United States, based on rules established by the Association of American Feed Control Officials (AAFCO) to ensure compliance with federal and state feed laws.  Pet food labels must include: 1. the food type and product name, 2. net weight, 3. guaranteed analysis, 4. ingredient content, 5. manufacturer's or distributor's name and address, and 6. "a claim that the pet food meets or exceeds the requirements of one or more of the recognized categories of nutritional adequacy: gestation, lactation, growth, maintenance, and complete for all life stages…; unless another scientifically substantiated claim is made, the food is designated solely for intermittent or supplemental feeding, or is to be used on the advice of a veterinarian."

1.  The “food type” means that the label must state whether it is made for cats or dogs.  The product name describes the food, and many words are used as part of the product name to appeal to consumers, such as “dinner, platter…”.  AAFCO has rules for their use:

If you see:

The product must contain:

Beef (or other meat)

At least 95% beef (minus water for processing)

Beef Dinner (entree, etc.)

25-94% beef

With beef

At least 3% beef

Beef Flavor

A “detectable” amount

2. The net weight is the amount of food in the container, often in pounds and grams.  It may give a rough estimate of the energy density of canned foods, many of which contain about 1 Cal/gram as fed.  One reason to read the net weight when comparing foods is that manufacturers sometimes reduce the size of containers without changing the price.  For example, what many think of as a “16 oz.” can is really 13.2 oz., and a “6 oz.” can really may be 5.5 oz.

3. The guaranteed analysis must list minimum % of crude protein and fat, and maximum % of crude fiber and moisture present in the product.  Although a legal requirement, the guaranteed analysis is of little value.  The methods are antiquated and non-specific, and the numbers provide only minimums or maximums, not actual amounts.  More accurate analyses are often available by request from manufacturers.  Manufacturers also often list other constituents not required by AAFCO, sometimes seemingly for marketing rather than nutritional reasons.

4. The ingredient list falls into five major categories:  water, energy sources, protein sources, and vitamins and minerals added to balance the food, as well as a variety of other substances added for different reasons.  Animals don’t have “ingredient requirements”; they need nutrients, which are contained in ingredients.  Thus, a wide variety of ingredients can be combined to produce a nutrient profile appropriate for the pet the diet is intended for.  Ingredient names have specific legal meanings, defined by AAFCO, which are somewhat imprecise to allow for normal variation in feedstuffs and processing procedures.  Moreover, it is not possible to judge the quality of the diet by the ingredient list, or the quality of the ingredient by its name.    AAFCO also requires that ingredients be listed "in descending order by their predominance by weight".  "Descending order" must be evaluated carefully to avoid being misled.  For example, a meat source like “fresh beef” followed by two or three grain sources may indicate that grain, not meat, is the primary ingredient.  This is because it means that the meat contains its natural water content (up to 75% of its weight), which is removed during processing of dry foods.

5. The manufacturer or distributor must provide a name and address on the label to identify the source of the product and permit the consumer or other interested person to contact the producer of the food.  Many commercial foods also provide a toll-free telephone number or website, which may provide information concerning the food.

6. A claim of "complete and balanced" also must appear on the label.  This claim may be met in any of three ways.  The first is by calculation; if a manufacturer can calculate that the combination of ingredients used "meets or exceeds" recommended nutrient levels from published nutrient composition tables, the claim may be made on this basis.  The second method is by analysis of the diet.  If chemical analysis shows that the food contains levels of nutrie­nts that exceed recommended minimums, it also may claim nutritional adequacy.  Unfortunately, these methods are of very little practical value in the veterinary evaluation of pet foods.  The analytical profile of many pet food ingredients is too variable for "book values" to be useful, and provides no measure of nutrient availability.  Moreover, nutrient excesses or unmeasured toxic substances could be present, and one could not know if pets would eat the food.  The third, and best, method of establishing a nutritional claim is by "protocol testing".  These tests require the food to be fed during the period, often gestation, lactation and growth, for which the claim is made.  One limitation of AAFCO label guarantees as currently presented is that there is no requirement for retesting.  Even with this limitation, feeding tests currently are the most valid way to ensure that the food can actually meet the nutritional needs of pets to which it is fed.  Despite the required amount of information, evaluation of the label may not be sufficient to predict the quality or price of the food.  The FDA also regulates health claims on pet foods.

A relatively recent label development is the presence of so-called descriptive terms.  Recently, terms “light,” “lean,” “low,” or “reduced” calorie or fat have been approved by AAFCO to appear on pet food labels.  The term refers to energy density in kcal/kilogram diet, calibrated by the % moisture.  The definitions for dog and cat foods are presented in the table below.

Term

< 20% H2O

20-65% H2O

> 65% H2O

“Light”, “lite”, “low calorie” 

Dog

<3100 kcal/kg

<2500 kcal/kg

<900 kcal/kg

Cat

<3250 kcal/kg

<2650 kcal/kg

<950 kcal/kg

“Lean”, “low fat”

Dog

<9% fat

<7% fat

<4% fat

Cat

<10% fat

<8% fat

<5% fat

These terms permit manufacturers to draw attention to foods with reduced calorie and fat content.  Unfortunately, as is the case with human foods, these terms ignore the fact that energy and fat intake are feeding issues rather than diet issues.   The increase in “low-fat” human foods during the last two decades of the 20th century has been associated with a relentless increase in the number of obese humans.  Thus, unless food intake is controlled, the nutrient density of the diet cannot moderate body condition, seductive as the promise might be.

Similarly, terms such as “promotes urinary tract health” on commercial cat food labels have little veterinary value.  This expression, coined in the 1980’s, was intended to convey the diet’s formulation to reduce the risk of struvite stone formation.  The subsequent increase in the prevalence of calcium oxalate stones, and the recognition that stones are not the most common cause of signs of lower urinary tract signs, makes this term of limited and questionable descriptive value.

There is a more comprehensive discussion of pet food labels is available on the FDA’s website.