What’s in Pet Food?

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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 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 offences.

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 throw always, grains considered “unfit for human consumption,” and similar waste products to be turned into profit. This waste includes intestines, udders, oesophagi, and possibly diseased and cancerous animal parts.

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),
  • Heinz (9 Lives, Amore, Gravy Train, Kibbles n Bits, Recipe, Vets),
  • Colgate-Palmolive (Hill’s Science Diet Pet Food).

Other leading companies are:

  • Procter & Gamble (Eukanuba and Iams),
  • Mars (Kal Kan, Mealtime, Pedigree, Sheba), and
  • Nutro

From a business standpoint, multinational companies owning pet food manufacturing companies is an ideal relationship. The multinationals have a captive market in which to capitalize on their waste products, and the pet food manufacturers have a reliable source from which to purchase their bulk materials.

There are hundreds of different pet foods available in this country. And while many of the foods on the market are virtually the same, not all of the pet food manufacturing companies use poor quality and potentially dangerous ingredients.

Specific pet food ingredients

Animal and poultry fat

You may have noticed a unique, pungent odour 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, is usually 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 dried kibbles or extruded pellets to make an otherwise bland or distasteful product palatable. The fat also acts as a binding agent to which manufacturers add other flavour 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 fibber, 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 fulfil certain physiological needs – one may wonder why we are feeding a corn-based product to them. The answer is that corn is much cheaper 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 mould) 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 25 dogs

Although it caused many dogs to vomit, stop eating, and have diarrhoea, 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.”

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 colours and flavours 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 contain preservatives. Some of these 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 included 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, 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 only approved for use in human food for preserving spices, such as cayenne and chilli powder, at a level of 100 ppm – but it would be very difficult to consume as much chilli 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. Fish meal, and some prepared vitamin mixtures used to supplement pet food, contain chemical preservatives. This means that your companion animal may be eating food containing several types of preservatives. Not all of these are required to be disclosed on the label.

However, due to consumer pressure, preservatives used in fat are now required to be listed on the label:

  • Additives in Processed Pet Foods
  • Anticaking agents
  • Antimicrobial agents
  • Antioxidants
  • Colouring agents
  • Curing agents
  • Drying agents
  • Emulsifiers
  • Firming agents
  • Flavour enhancers
  • Flavouring agents
  • Flour treating agents
  • Formulation aids
  • Humectants
  • Leavening agents
  • Lubricants
  • Nonnutritive sweeteners
  • Nutritive sweeteners
  • Oxidizing and reducing agents
  • pH control agents
  • Processing aids
  • Sequestrants
  • Solvents, vehicles
  • Stabilizers, thickeners
  • Surface active agents
  • Surface finishing agents
  • Synergists
  • Texturizers

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 do not carry the unanswered questions about their safety.

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