What's Really in Pet Food
Animal Protection Institute
Plump whole chickens, choice cuts of beef, fresh grains, and all the wholesome nutrition your
dog or cat will ever need.
These are the images pet food manufacturers promulgate through the media and
advertising. This is what the $11 billion per year U.S. pet food industry wants consumers to
believe they are buying when they purchase their products.
This report explores the differences between what consumers think they are buying and
what they are actually getting. It focuses in very general terms on the most visible name
brands -- the pet food labels that are mass-distributed to supermarkets and discount stores --
but there are many highly respected brands that may be guilty of the same offenses.
What most consumers don't know is that the pet food industry is an extension of the human
food and agriculture industries. Pet food provides a market for slaughterhouse offal, grains
considered "unfit for human consumption," and similar waste products to be turned into
profit. This waste includes intestines, udders, esophagi, and possibly diseased and cancerous
Three of the five major pet food companies in the United States are subsidiaries of major
multinational companies: Nestlé (Alpo, Fancy Feast, Friskies, Mighty Dog, and Ralston Purina
products such as Dog Chow, ProPlan, and Purina One), Heinz (9 Lives, Amore, Gravy Train,
Kibbles-n-Bits, Nature's Recipe), Colgate-Palmolive (Hill's Science Diet Pet Food). Other
leading companies include Procter & Gamble (Eukanuba and Iams), Mars (Kal Kan, Mealtime,
Pedigree, Sheba, Waltham's), and Nutro. From a business standpoint, multinational
companies owning pet food manufacturing companies is an ideal relationship. The
multinationals have increased bulk-purchasing power; those that make human food products
have a captive market in which to capitalize on their waste products, and pet food divisions
have a more reliable capital base and, in many cases, a convenient source of ingredients.
There are hundreds of different pet foods available in this country. And while many of the
foods on the market are similar, not all of the pet food manufacturing companies use poor
quality or potentially dangerous ingredients.
Although the purchase price of pet food does not always determine whether a pet food is
good or bad, the price is often a good indicator of quality. It would be impossible for a
company that sells a generic brand of dog food at $9.95 for a 40-lb. bag to use quality
protein and grain in its food. The cost of purchasing quality ingredients would be much
higher than the selling price.
The protein used in pet food comes from a variety of sources. When cattle, swine, chickens,
lambs, or other animals are slaughtered, the choice cuts such as lean muscle tissue are
trimmed away from the carcass for human consumption. However, about 50% of every
food-producing animal does not get used in human foods. Whatever remains of the carcass --
bones, blood, intestines, lungs, ligaments, and almost all the other parts not generally
consumed by humans -- is used in pet food, animal feed, and other products. These "other
parts" are known as "by-products," "meat-and-bone-meal," or similar names on pet food
The Pet Food Institute -- the trade association of pet food manufacturers -- acknowledges
the use of by-products in pet foods as additional income for processors and farmers: "The
growth of the pet food industry not only provided pet owners with better foods for their
pets, but also created profitable additional markets for American farm products and for the
byproducts of the meat packing, poultry, and other food industries which prepare food for
Many of these remnants provide a questionable source of nourishment for our animals. The
nutritional quality of meat and poultry by-products, meals, and digests can vary from batch to
batch. James Morris and Quinton Rogers, two professors with the Department of Molecular
Biosciences, University of California at Davis Veterinary School of Medicine, assert that, "There
is virtually no information on the bioavailability of nutrients for companion animals in many of
the common dietary ingredients used in pet foods. These ingredients are generally
by-products of the meat, poultry and fishing industries, with the potential for a wide variation
in nutrient composition. Claims of nutritional adequacy of pet foods based on the current
Association of American Feed Control Officials (AAFCO) nutrient allowances ('profiles') do not
give assurances of nutritional adequacy and will not until ingredients are analyzed and
bioavailability values are incorporated."2
Meat and poultry meals, by-product meals, and meat-and-bone meal are common ingredients
in pet foods. The term "meal" means that these materials are not used fresh, but have been
rendered. What is rendering? Rendering, as defined by Webster's Dictionary, is "to process as
for industrial use: to render livestock carcasses and to extract oil from fat, blubber, etc., by
melting." Home-made chicken soup, with its thick layer of fat that forms over the top when
the soup is cooled, is a sort of mini-rendering process. Rendering separates fat-soluble from
water-soluble and solid materials, removes most of the water, and kills bacterial contaminants,
but may alter or destroy some of the natural enzymes and proteins found in the raw
ingredients. Meat and poultry by-products, while not rendered, vary widely in composition
What can the feeding of such products do to your companion animal? Some veterinarians
claim that feeding slaughterhouse wastes to animals increases their risk of getting cancer and
other degenerative diseases. The cooking methods used by pet food manufacturers -- such
as rendering, extruding (a heat-and-pressure system used to "puff" dry foods into nuggets or
kibbles), and baking -- do not necessarily destroy the hormones used to fatten livestock or
increase milk production, or drugs such as antibiotics or the barbiturates used to euthanize
Animal and Poultry Fat
You may have noticed a unique, pungent odor when you open a new bag of pet food --
what is the source of that delightful smell? It is most often rendered animal fat, restaurant
grease, or other oils too rancid or deemed inedible for humans.
Restaurant grease has become a major component of feed grade animal fat over the last
fifteen years. This grease, often held in fifty-gallon drums, may be kept outside for weeks,
exposed to extreme temperatures with no regard for its future use. "Fat blenders" or
rendering companies then pick up this used grease and mix the different types of fat
together, stabilize them with powerful antioxidants to retard further spoilage, and then sell
the blended products to pet food companies and other end users.
These fats are sprayed directly onto extruded kibbles and pellets to make an otherwise bland
or distasteful product palatable. The fat also acts as a binding agent to which manufacturers
add other flavor enhancers such as digests. Pet food scientists have discovered that animals
love the taste of these sprayed fats. Manufacturers are masters at getting a dog or a cat to
eat something she would normally turn up her nose at.
Wheat, Soy, Corn, Peanut Hulls, and Other Vegetable Protein
The amount of grain products used in pet food has risen over the last decade. Once
considered filler by the pet food industry, cereal and grain products now replace a
considerable proportion of the meat that was used in the first commercial pet foods. The
availability of nutrients in these products is dependent upon the digestibility of the grain. The
amount and type of carbohydrate in pet food determines the amount of nutrient value the
animal actually gets. Dogs and cats can almost completely absorb carbohydrates from some
grains, such as white rice. Up to 20% of the nutritional value of other grains can escape
digestion. The availability of nutrients for wheat, beans, and oats is poor. The nutrients in
potatoes and corn are far less available than those in rice. Some ingredients, such as peanut
hulls, are used for filler or fiber, and have no significant nutritional value.
Two of the top three ingredients in pet foods, particularly dry foods, are almost always some
form of grain products. Pedigree Performance Food for Dogs lists Ground Corn, Chicken
By-Product Meal, and Corn Gluten Meal as its top three ingredients. 9 Lives Crunchy Meals for
cats lists Ground Yellow Corn, Corn Gluten Meal, and Poultry By-Product Meal as its first three
ingredients. Since cats are true carnivores -- they must eat meat to fulfill certain physiological
needs -- one may wonder why we are feeding a corn-based product to them. The answer is
that corn is a much cheaper "energy source" than meat.
In 1995, Nature's Recipe pulled thousands of tons of dog food off the shelf after consumers
complained that their dogs were vomiting and losing their appetite. Nature's Recipe's loss
amounted to $20 million. The problem was a fungus that produced vomitoxin (an aflatoxin or
"mycotoxin," a toxic substance produced by mold) contaminating the wheat. In 1999,
another fungal toxin triggered the recall of dry dog food made by Doane Pet Care at one of
its plants, including Ol' Roy (Wal-Mart's brand) and 53 other brands. This time, the toxin killed
Although it caused many dogs to vomit, stop eating, and have diarrhea, vomitoxin is a milder
toxin than most. The more dangerous mycotoxins can cause weight loss, liver damage,
lameness, and even death as in the Doane case. The Nature's Recipe incident prompted the
Food and Drug Administration (FDA) to intervene. Dina Butcher, Agriculture Policy Advisor for
North Dakota Governor Ed Schafer, concluded that the discovery of vomitoxin in Nature's
Recipe wasn't much of a threat to the human population because "the grain that would go
into pet food is not a high quality grain."3
Soy is another common ingredient that is sometimes used as a protein and energy source in
pet food. Manufacturers also use it to add bulk so that when an animal eats a product
containing soy he will feel more sated. While soy has been linked to gas in some dogs, other
dogs do quite well with it. Vegetarian dog foods use soy as a protein source.
Additives and Preservatives
Many chemicals are added to commercial pet foods to improve the taste, stability,
characteristics, or appearance of the food. Additives provide no nutritional value. Additives
include emulsifiers to prevent water and fat from separating, antioxidants to prevent fat from
turning rancid, and artificial colors and flavors to make the product more attractive to
consumers and more palatable to their companion animals.
Adding chemicals to food originated thousands of years ago with spices, natural
preservatives, and ripening agents. In the last 40 years, however, the number of food
additives has greatly increased.
All commercial pet foods must be preserved so they stay fresh and appealing to our animal
companions. Canning is a preserving process itself, so canned foods contain less preservatives
than dry foods. Some preservatives are added to ingredients or raw materials by the
suppliers, and others may be added by the manufacturer. Because manufacturers need to
ensure that dry foods have a long shelf life to remain edible after shipping and prolonged
storage, fats used in pet foods are preserved with either synthetic or "natural" preservatives.
Synthetic preservatives include butylated hydroxyanisole (BHA) and butylated hydroxytoluene
(BHT), propyl gallate, propylene glycol (also used as a less-toxic version of automotive
antifreeze), and ethoxyquin. For these antioxidants, there is little information documenting
their toxicity, safety, interactions, or chronic use in pet foods that may be eaten every day
for the life of the animal.
Potentially cancer-causing agents such as BHA, BHT, and ethoxyquin are permitted
at relatively low levels. The use of these chemicals in pet foods has not been thoroughly
studied, and long term build-up of these agents may ultimately be harmful. Due to
questionable data in the original study on its safety, ethoxyquin's manufacturer, Monsanto,
was required to perform a new, more rigorous study. This was completed in 1996. Even
though Monsanto found no significant toxicity associated with its own product, in July 1997,
the FDA's Center for Veterinary Medicine requested that manufacturers voluntarily reduce
the maximum level for ethoxyquin by half, to 75 parts per million. While some pet food critics
and veterinarians believe that ethoxyquin is a major cause of disease, skin problems, and
infertility in dogs, others claim it is the safest, strongest, most stable preservative available for
pet food. Ethoxyquin is approved for use in human food for preserving spices, such as
cayenne and chili powder, at a level of 100 ppm -- but it would be very difficult to consume
as much chili powder every day as a dog would eat dry food. Ethoxyquin has never been
tested for safety in cats.
Some manufacturers have responded to consumer concern, and are now using "natural"
preservatives such as Vitamin C (ascorbate), Vitamin E (mixed tocopherols), and oils of
rosemary, clove, or other spices, to preserve the fats in their products. Other ingredients,
however, may be individually preserved. Most fish meal, and some prepared vitamin-mineral
mixtures, contain chemical preservatives. This means that your companion animal may be
eating food containing several types of preservatives. Federal law requires preservatives to be
disclosed on the label; however, pet food companies only recently started to comply with
Additives in Processed Pet Foods
Flour treating agents
Oxidizing and reducing agents
pH control agents
Surface active agents
Surface finishing agents
While the law requires studies of direct toxicity of these additives and preservatives, they
have not been tested for their potential synergistic effects on each other once ingested.
Some authors have suggested that dangerous interactions occur among some of the
common synthetic preservatives. Natural preservatives do not provide as long a shelf life as
chemical preservatives, but they are safe.
Excerpted from API's investigative report on "What's Really In Pet Food."
Copyright © 1997-2002 Animal Protection Institute.
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