Cat Food Labels

This is a guide on how to interpret pet food labels in America. The laws are shoddily enforced and pet food manufacturers are more-or-less self-policing (as the 2007 pet food recall and fallout demonstrated), but this page explains the most basic guidelines there are.

The Basics

Ingredients on the label must be listed in descending order according to weight.

Sounds simple enough, but pet food manufacturers can be tricky about this. To illustrate: a dry food ingredient list may read something like “Chicken, corn gluten meal, poultry by-product meal, ground yellow corn, brewer’s rice, chicken fat (preserved with mixed tocopherols)….” You think oooooh, chicken’s the first ingredient, how nice.

Hold up.

Ingredient Splitting

Notice that corn actually appears twice in the listing, once as corn gluten meal and once as ground yellow corn, and brewer’s rice is right on its heels. By separating plant ingredients of the same species into different components, manufacturers can make them appear lower on the list while still adding substantial amounts to the food.

This trick is known as “ingredient splitting.” It’s a good way to make your food look like it contains a lot more food than it actually does.

Water Weight is a Thing

Listing “chicken” at the very top gives you the impression that it’s the main protein source—however,  you need to know the weight of an ingredient includes pre-cooking water content. So since dry food has most of the water removed, and since chicken is about 70% water… at the end of it, there’s really not that much real chicken in the food at all. Poultry by-product meal is the primary animal protein source in this food, because meat meals have most of their water and fat removed before being added to the extruder.

When it comes down to it, the plant ingredients potentially outweigh the animal ingredients in this particular example of dry food.

Ingredient names must adhere (mostly) to standard definitions as established by the AAFCO.

The AAFCO is the American Association of Feed Control Officials, and no, it’s not a regulatory body, it’s merely an association that comes up with standards and suggestions for regulations to be implemented by regulatory bodies (in the case of pet food, usually the state government).

Manufacturers must list all the ingredients in the food on the label and the names have to adhere to AAFCO guidelines, BUT they only need to list what they add at their manufacturing plant. This is a pretty big loophole, since this means that if they receive a shipment of fish meal that has ethoxyquin already added to it (and ethoxyquin is the preservative of choice for many fish meal providers), they don’t need to include that information on their label.

How to Interpret the Names on Labels

If it says just an ingredient name with no modifiers, e.g., “Tuna for cats” or “Tuna cat food”, that means the ingredient must make up at least 95% of the food on a dry-matter basis (70% if including water).

If an ingredient name is followed by a modifier, e.g., “Beef Platter for cats”, that means the ingredient must make up at least 25% of the food. If there are two ingredients followed by a modifier, e.g. “Beef and Wheat Germ Dinner for Cats,” that means the two ingredients must make up at least 25% of the food, with more beef than wheat germ since it’s mentioned first. At least 3% of the total weight of the food must come from the second named ingredient.

If an ingredient is preceded by “with“, e.g., “Cat Food With Chicken Giblets,” it means the named ingredient must make up at least 3% of the food. It can often easily be confused with the term “Chicken Giblet Cat Food”—but the “with” makes ALL the difference in the world.

If the ingredient is coupled with “flavor,” e.g., “Turkey Flavored Cat Food,” it means that somewhere down the line the pet food might have brushed up against a real turkey. Maybe. Basically, it just needs to have some kind of flavoring in there that’s turkey-based, enough to be “detectable.” This is pretty rare for cat foods, though, and something you’re much more likely to see in treats or dog foods.

And of course pet food manufacturers can come up with any number of names that don’t indicate the percentage of ingredients. “Mixed Grill” is an example, “Premium Feast” would be another. There is absolutely no requirement in this case for the manufacturers to adhere to any sort of minimum ingredient requirements.

Allowable Ingredient Variation

Did you know that pet food labels need to be in close agreement with the listed ingredients only once every six months? As long as “nutrient requirements are met”, there can be pretty significant variation (up to 25%) the rest of the year.

Statements of Nutritional Adequacy

You have probably noticed statements on pet food that say something like “Animal feeding tests using AAFCO procedures substantiate that this food provides complete and balanced nutrition for feline growth and reproduction.”

Pet foods can claim that they are formulated to meet AAFCO standards for pet nutrition through four ways: by calculation, by chemical analysis, by feeding trials, and by equivalence.

Calculation basically means somebody with a nutrient database crunches the numbers for the various ingredients and then compares it with the AAFCO nutrient profiles.

Chemical analysis means that… well, it’s pretty clear, right? People with beakers and retorts and test tubes, dissolving shit with solvents and coming up with the numbers that way.

Neither of these two methods establish any kind of reliable figure for bioavailability.

The third method, feeding trials, does establish that the food is adequate for meeting nutritional needs—i.e., that it doesn’t kill the test subjects within six months (ten weeks if it’s a kitten).

Another way food manufacturers can claim nutritional adequacy is by equivalence: if the food is in the same “family” as one of the products that have undergone feeding trials, they can claim that the product “provides complete and balanced nutrition” that is “comparable in nutritional adequacy to a product which has been substantiated using AAFCO feeding tests.”

So what are the feeding trials?

Y’all, it’s not that hard to pass a feeding trial; history, if nothing else, has shown us how many foods with serious nutritional deficiencies are passed as “complete and balanced.” 2017 saw at least one cat food recall for deficient thiamine levelsSmall Animal Clinical Nutrition 4th ed. is rife with cases, including one in which several cats came down with severe copper deficiency while eating a commercial food that had passed feeding trials for growth and reproduction. The 1980s provides the most infamous example of a “complete and balanced diet” actually turning out to be dangerously lacking in taurine: many cats suffered from many classic symptoms of taurine deficiency (retinal atrophy, cardiomyopathy) while eating cat food that had passed AAFCO feeding trials.

Here are the requirements for feeding trials to prove adequacy for adult cat maintenance:

  • Only 8 cats need to participate.
  • Only 6 of these 8 need to complete the trial (i.e. no more than 25% can drop dead during or be pulled from the trial)
  • The trial is only for 26 weeks (6 months)
  • Cats are allowed to lose up to 15% of their original body weight and still pass
  • No signs of pathological nutritional deficiency must be evident at the end of the trial
  • 4 blood values (hemoglobin, packed cell volume, serum alkaline phosphatase and serum albumin) must not fall below the established minimums

Requirements for feeding trials to prove adequacy for pregnant/lactating cats and kittens:

  • Only 8 pregnant queens or 8 kittens need to participate
  • 6 of these 8 need to finish the trial
  • The trial lasts only 10 weeks for kittens, or from estrus until 6 weeks after birth for reproduction
  • The weight of the kittens born to the queens must not be below 75% of the “colony average”
  • 80% of all kittens that survive 24 hours after being born to the pregnant queens must finish the trial
  • For kitten food trials, the kittens must be fully weaned but not older than 8 weeks at the beginning of the trial
  • No signs of pathological nutritional deficiency must be evident in the kittens or in the queens and the kittens born to them at the end of the trial
  • The same 4 blood values above are checked for mandatory minimums

Adherence to nutritional guidelines is pretty fast and loose in any case—as this 2017 study shows. Out of 21 tested foods, 16 deviated substantially from nutritional guidelines, and 12 were really, really high in phosphorus and calcium.

(Unless noted otherwise, information above obtained from Small Animal Clinical Nutrition, 4th ed.)

How To Calculate Dry Matter Percentages in Cat Food

When you look at the guaranteed analysis on cat food labels, you’ll notice that dry food appears to be much higher in protein and fat than canned food. Appearances are deceptive, however, because once you remove the water content, the average can of canned food is much higher in protein than the average dry cat food formula.

In order to make an accurate nutrient comparison for any sort of food, you need to compare the food only after all the water is extracted.

But be aware that dry matter calculations for cat food based on the numbers on the labels are only approximate. That’s because all we’re typically given are maximums/minimums (which yet again gives manufacturers lots of wiggle room). If you’re truly concerned about the nutritional values, write or call the manufacturer and get the as-fed values.

So let’s compare two different types of food from the same company: Wellness.

Wellness Complete Kitten Grain-Free dry food contains:
40% crude protein min. protein
18% crude fat min. fat
10% moisture max. moisture

dry weight Calculation for Dry food

Subtract the water content from the food:

100 – 10 = 90

This is the total dry matter percentage, and the number you’ll use as the base for the protein and fat percentages.

To get dry matter protein, divide the protein percentage by the total dry matter percentage:

40 / 90 x 100 = 44.44%

To get dry matter fat, divide the fat percentage by the total dry matter percentage:

18 / 90 x 100 = 20%

Conclusion: 44.44% (ish) protein content, 20%  (ish) fat content, for a total of 64.44% non-carb, non-ash content. Not so bad, right? Well, check this out:

dry weight Calculation for wet food

Wellness Kitten canned food contains:

11 % crude protein min. protein
6% crude fat min. fat
78% moisture  max moistureSubtract the water content from the food:

100 – 78 = 22%

This is the total dry matter percentage, and the number you’ll use as the base for the protein and fat percentages.

To get dry matter protein, divide the protein percentage by the total dry matter percentage:

11/ 22 x 100 = 50%

To get dry matter fat, divide the fat percentage by the total dry matter percentage:

6 / 22 x 100 = 27.27%

In short: the canned kitten food, at 77.27% combined protein and fat, is substantially higher than the kibble in both protein and fat—even the grain-free formulation. This holds true for most dry and canned foods. Unless you’re feeding an exceptionally high-protein dry food like EVO or Wellness CORE, or unless you’re feeding a protein-restricted canned food, a cat eating canned food will always end up eating more protein in a day than a cat eating dry, assuming you’re feeding the same number of calories.