How GoodGuide Rates Pet Foods


GoodGuide's Health ratings for pet food products are based on four attributes:

  • the nutritional adequacy of the food, as demonstrated by feeding trials or formulation testing,
  • caloric content disclosure,
  • life stage specificity, and
  • an assessment of whether product ingredients are desirable in high quantities, desirable or less desirable.

Product-level data on environmental performance are generally unavailable for specific pet food products, so GoodGuide relies on company-level environmental scores to characterize the performance of a product on this dimension.

Product-level data on societal performance are generally unavailable for specific pet food products, so GoodGuide relies on company-level social scores to characterize the performance of a product on this dimension.

Scoring Methodology

Health Indicator Selection and Impact on Scores
Pet food is a commonly purchased product that most people know very little about. Creating a rating system that is both meaningful and science-based is challenging for a variety of reasons. Transparency about ingredients, ingredient sources, and processing methods beyond the minimum of what is legally required is generally difficult to come by in the pet food industry. In addition, the nutrient-based scientific literature is not comprehensive, especially when compared to the research base for human nutrition.

In order of importance, the following criteria were selected as the best available indicators of a product's nutritional value and potential impact on pet health:

Nutritional Adequacy (Most important)

  • Regulations developed by the Association of American Feed Control Officials (AAFCO) require the presence of a nutritional adequacy statement on all pet food packages. Nutritional adequacy can be met either through feeding trials or through formulated tests. Feeding trials are conducted with animals to ensure that nutrients in a given food or line of foods are a) present in sufficient quantities to promote good health and b) bio-available to the animal ensuring the nutrients are digested properly. Formulated products are generally laboratory tested to confirm nutrient content, not tested with animals. Since feeding trials allow for an in vivo product evaluation, they are preferred over formulations.

Caloric Content Disclosure

  • Given the growing concern about obesity in pets, caloric disclosure and labeling is essential for consumers to purchase pet foods that meet the energy needs of their pets. Unfortunately, caloric disclosure is not currently required by regulation and is optional for manufacturers. Without information on caloric content, pet owners run the risk of overfeeding their pets, which may result in obesity and related health problems. As a result, products that disclose their caloric content receive a higher score for allowing consumers to select more appropriate feeding portions. Scoring is based only on disclosure, not the actual caloric density of the food.

Life Stage

  • AAFCO requires that foods meet and disclose one of two nutrient profiles based on the pet's life stage. The “maintenance” life stage nutrient profile is designed to meet the nutritional needs for adults. The “growth and reproduction” nutrient profile is designed to meet the nutritional needs for puppies/kittens as well as pregnant or lactating adults. Products that meet both standards are designated as 'all stages'. Pet food products designed for a single life-stage (i.e. 'maintenance' or 'growth and reproduction') better match the nutrient profiles for pets in that life stage. All Stages products may contain excessive amounts of some nutrients, which can result in overfeeding. The preferred practice is to feed pets with food designed for a single life stage.

Ingredients (Least important)**

  • As long as a manufacturer passes an AAFCO nutritional adequacy test, there are few limits on what ingredients can go into a pet food. To systematically account for the wide variety of ingredients and different formulations, GoodGuide categorized each cat food and dog food ingredient into one of four categories from a health perspective: 'desirable in high quantities', 'desirable', 'less desirable', or 'extraneous' as described below:

    • Most 'desirable in high quantities' ingredients are categorized as a source of many nutrients, and should generally be present in high quantities in the food. The threshold for 'high quantity' was assigned to the first five ingredients listed in the ingredient statement.
    • Desirable ingredients include many nutrients and sources of soluble fiber that are important for health, but need not be present in high quantities such as vitamins (i.e. listed within the first five ingredients).
    • In most cases, less desirable ingredients are those that have low nutrient bioavailability, provide non-nutritional content to the food (e.g. artificial colors or stabilizers), are undefined by AAFCO, or are potentially harmful. Many fruits, vegetables, and other seemingly healthy ingredients are identified as less desirable because there is no AAFCO definition for the ingredient. If an ingredient definition does not exist, AAFCO regulations state that it “shall be identified by the common or usual name.” For example, 'Apples' may contain seeds, stems, leaves, skins, or pulp. While apple pulp may contribute nutrients to the food, the generic definition does not clearly exclude any other parts that may not be beneficial to the animal's health. For this reason, ingredients without definitions are designated as 'less desired'. Scores for foods containing any potentially harmful ingredients, such as garlic, are capped at a maximum of 2 for this criterion.
    • Extraneous ingredients do not impact scoring and include ingredients such as: water, broth, non-essential nutrients, and manufactured flavoring agents.
  • The relative frequency of ingredients in each category was calculated using the above categories. Ingredient counts by category were translated into a summary ingredient score by applying a weighted equation. Based on our ingredient assessment and categorization, we made the judgment that 'desirable' ingredients are 2-3X more important than 'less desirable' ingredients and 'desirable in high quantity' ingredients are 1.5-2X more important than 'desirable' ingredients.


Regulatory Compliance Drives Product Health Scores
Most of the data available on pet foods is derived from regulatory disclosures mandated by AAFCO and the FDA. GoodGuide assumes compliance with relevant pet food standards ensures that a product is at least healthy for a pet. Since most mainstream pet foods meet AAFCO standards for nutrition (which are based on veterinary science research from the National Research Council), most pet foods receive a score between 5 and 10 for Health.

Whether existing standards are sufficiently protective of pet health is a source of uncertainty. Current regulations are relatively generic and do not address or control many of the health-based marketing claims that consumers see on store shelves. Other attributes, such as the presence of unsubstantiated or misleading claims in the display panel, transparency regarding quality assurance procedures, use of adulterated ingredients, misrepresentation of health claims through marketing language, adherence to National Research Council nutrient profiles, disclosure of feeding guideline increments, and disclosure of ingredient sources would also be good indicators of health for pet foods, but most products on the market do not disclose the information required to conduct more detailed evaluations.

Ingredient Assessment Limitations
Due to the challenges inherent in categorizing pet food ingredients and the systematic 'high quantity' definition, the ingredient criterion is less meaningful than the other criteria. Data problems affecting ingredient assessment include:

There is no generally accepted systematic practice for defining ingredients that are present in 'high quantity' (so GoodGuide assumes the first five ingredients on a product label are in this category).

Ingredient order can be manipulated by using high weight, water-dense ingredients, or by “splitting” ingredients such as wheat into components such as wheat middlings, wheat flour and wheat germ meal.

AAFCO ingredient definitions can be vague. For example, 'meat by-products' can contain liver, kidney and lungs (high in nutrient value), or udder, bone and connective tissue (poor in nutrient value).

GoodGuide's Science Team worked closely with a Diplomate of the American College of Veterinary Nutrition (ACVN) to ensure that our ratings criteria were science-based, and feedback from these experts consistently indicated that reliance on pet food ingredient categorization alone would be a poor indicator of a product's overall health impact for a pet.