Photo: ehow.com

Simply put, a filler is something that has been added to your dog's food to help him feel "full" but contains little to no nutritional value.

Some fillers can actually irritate your dog's digestive system. So, if you have an older dog or an animal with health problems, feeding a food without fillers may improve his or her overall health and wellbeing.

While a food with fillers will temporarily satisfy your dog's hunger, you will likely need to feed more of it. Because of the lack of nutrition, your dog's body will tell him that he needs more food. It's like eating a candy bar. While it might satisfy you for a while, you will likely be hungry again soon as your body craves the vitamins and minerals it needs. Generally, when you switch your dog from a filler-laden food to one free of fillers, you will notice a decrease in the amount needed to keep him healthy and satisfied.

Foods high in fillers are often sprayed with animal fat to make them more palatable to your dog.

Fillers also carry with them the risk of being contaminated with pesticides and other harmful chemicals. Both 2006 and 2007 pet food recalls were the result of contaminated fillers.

Pet food manufacturers will add fillers in order to reduce the overall cost of the food. However, you will likely need to buy the food more often as your dog consumes higher quantities of it. Buying a higher quality food might cost more on the front end, but once your dog reduces his intake, the cost per meal can be lower than that of the low quality, inexpensive food. Generally, foods sold at grocery and several sold at large pet food retailers, such as PetSmart and Petco will contain some level of filler. And, as the price decreases, the amount of fillers will go up. Please note: This is not to say that EVERY food at these stores contains fillers. However, many do, but the amount will vary. Read the label carefully to evaluate the quality of the food.

Some common fillers include:

• Gluten and grain products, such as corn and wheat: These server as a source of sugar and, as dogs are carnivores, they are of little nutritional value. Often, a grain product will leave the body just as it entered as it will not be broken down or absorbed.
• Soy: This filler is responsible for a huge portion of pet allergies that can result in sneezing, itching, swelling, anaphylactic shock, and death.
• Seed hulls: Cottonseed and peanut hulls
• Weeds and straw
• Citrus pulp
• Beet pulp: While this can provide a good source of fiber, beet pulp has been known to plug the intestinal villus.
• Animal by-products: These are the "left-overs" once an animal has been prepared for human consumption. This may include intestines, chicken heads, lungs, livers, kidneys, duckbills, chicken and turkey feet, feathers and bone. Ingredients listed as chicken, beef, poultry, and animal by-products are not required to include actual meat. Animal digest, animal fat, meat by-products, and chicken by-products are all animal by-products and are described in better detail below.
• Animal digest: Produced by chemical or enzymatic hydrolysis of an undecomposed animal. This has also been described as "manure" and "a cooked-down broth, which can be made from unspecified parts of unspecified animals. The animals used can be obtained from almost any source and no control is in place over quality or contamination. Any kind of animal can be included: "4-D animals" (dead, diseased, disabled, or dying prior to slaughter), goats, pigs, horses, rats, euthanized at animal shelters, restaurant and supermarket refuse and so on."
• Animal fat: Obtained from the tissues of animals during rendering or extracting and generally comes from an unknown origin. BHA, an artificial preservative suspected of causing cancer, may be used to preserve the animal fat.
• Meat by-products: These are the non-rendered parts, other than the meat, and are derived from slaughter animals. This includes, but is not limited to, the spleen, kidneys, livers, brain, lungs, blood, bone, stomachs, and intestines.
• Chicken by-product meal: Ground and rendered chicken products, including necks, feet, intestines, and undeveloped eggs.

To avoid fillers, look at the ingredients on your pet food. While some companies may list real meat as their number one ingredient, they may actually have more fillers, which reduces the ratio of quality ingredients to useless ones. The staff of natural pet stores such Mouthfuls or Wag n' Wash are happy to help you better understand fillers and select a high quality food for your dog.

What's the difference?

Natural, organic, holistic... as pet owners, we are constantly faced with these terms. As "green living" takes a stronger hold on the US, these descriptors are becoming more and more common. So, what do these terms actually mean, and is there a difference?

• Natural: AAFCO (American Association of Feed Control Officials) defines the word "natural", when used to describe a pet food as: "A feed or ingredient derived solely from plant, animal or mined sources, either in its unprocessed state or having been subjected to physical processing, heat processing, rendering, purification extraction, hydrolysis, enzymolysis or fermentation, but not having been produced by or subject to a chemically synthetic process and not containing any additives or processing aids that are chemically synthetic except in amounts as might occur unavoidably in good manufacturing practices."

ThePetCenter.com states: "When it comes to labeling commercial feeds, pet foods, and specialty pet foods the use of the term "natural" is only acceptable in reference to the product as a whole when all of the ingredients and components of ingredients meet the definition.  The use of the term "natural" on the label is false and misleading if any chemically synthesized ingredients are present in the product.  Prophylene Glycol and BHA (butylated hydroxyanisole) are two common examples of chemically synthesized ingredients found in some pet foods. The committee suggested that an exception be made for synthetic vitamin and mineral additives as long as the product is not used as a dietary supplement."

So, just because a food is labeled as "natural" doesn't necessarily mean it's the best choice to feed your dog. Natural essentially means that the ingredient has been minimally processed and was grown in a "natural environment" (ie. outside versus in a lab). Natural foods can still contain fillers, including grains, glutens, and soy. By-products that have been minimally processed may also be included in the food.

For example, let's take a look at Science Diet's Nature's Best dog food. Here is the beginning of the ingredient list for the Chicken & Brown Rice Dinner (all fillers, ingredients devoid of nutrition, and other undesirable ingredients are in bold):

Chicken, Brown Rice, Whole Grain Wheat, Cracked Pearled Barley, Soybean Meal, Chicken Meal, Pork Fat (preserved with mixed tocopherols and citric acid), Dried Egg Product, Natural Flavor, Whole Grain Oats, Apples, Cranberries, Soybean Oil, Peas, Carrots, Dried Beet Pulp...

• Organic: To be termed as "organic", a food must be grown without the use of pesticides, insecticides, or herbicides. However, these products may be used as a "last resort" in dire circumstances, and non-organic fertilizers may still be utilized in some instances. Organic meat must come from animals that were never administered antibiotics or growth hormone.

The organic industry is heavily regulated and many countries, including the US, Canada, the European Union, and Japan require organic farmers to attain special certification.

Keep in mind that an "organic dog food" may not be entirely comprised of organic ingredients. Read the ingredient label to determine how "organic" the food actually is.

If you can find a dog food that is mostly or entirely organic, chances are you're buying a quality food, but you'll still want to look out for grains and other fillers.

Click here to view the ingredients of Karma, a 95% organic dog food

• Holistic: "Holistic" refers to looking at something and treating it as a whole. Each ingredient in a holistic dog food should contribute to the animal's health in a different way and the recipe should work together. A product like sweet potato might be added for its dental benefits and because it's a good source of fiber. Then, to meet the protein needs, a meat, like bison or lamb, will be added to complement the sweet potato.

Dog foods labeled as "holistic" should comprise of natural ingredients of human-grade quality that are well-cared for during the creation of the product. These foods contain no byproducts or fillers, which makes them more easily digested. Feeding a holistic food will help you avoid most food-related allergies that your dog might have. Holistic dog foods have not yet been included in pet food recall.

Holistic foods are generally very high quality but be sure to do your own investigation by reading the ingredient list.

Click here for a great example of how Ultra Holistic Superfood considers each ingredient individually and how they work together as a team.

While the words natural, organic, and holistic tend to be used interchangeably, there can be a big difference. Always read the labels of your food so that you know what you're getting.

While scanning the label of your dog food, you might see some preservatives. Canned food is preserved by the air-tight container, but dried foods must contain a preservative to prevent spoilage. Artificial (also known as synthetic) preservatives can produce an apporoximate twelve-month shelf life while natural preservatives cut that amount down to six months.  Read on to learn about some common preservatives found in dog food.

BHA (Butylated hydroxyanisole)

BHA is a synthetic or artificial preservative commonly found in dry dog food. It is very similar to BHT and is a waxy solid used to prevent oxidation of dry food. Some sources have claimed that BHA is a potential cause of cancer in dogs.

BHT (Butylated hydroxytoluene)

A common artificial preservative much like BHA, this fat-soluble compound is used as a food additive to prevent the degredation or spoilage of dog food. BHA is also used in cosmetics, pharmaceuticals, jet fuels, rubber, petroleum products, electrical transformer oil, and embalming fluid. Like BHA, some state that BHT can cause cancer.

Ethoxyquin

This is another commly used synthetic preservative. Ethoxyquin causes the most concern among dog owners. Like BHA and BHT, some experts have claimed a potential link to pet cancer. Several studies, including one by the Department of Pathology at Nagoya City University Medical School in Japan has found Ethoxyquin to promote kidney and bladder cancer and stomach tumors. Ethoxyquin has also been blamed as a cause of disease, skin porblems, and infertility. This dog food preservative is currently regulated by the FDA as a pesticide.

Propyl gallate

Propyl gallate is a less frequently used artificial preservative that has also been linked to cancer. It is also used in skin antiseptics, astringents, cosmetics, hair products, adhesives, and lubricants.

Propylene glycol

An artificial preservative that is a less toxic version of antifreeze and is used to de-ice aircraft. Propylene glycol is used as an ingredient in paint balls, a working fluid in hydraulic presses, poison for ground beetles, pipe tobacco addittive to prevent drying, and in deodorant sticks.  Propylene glycol is not allowed in cat food as it has been shown to cause anemia. However, it is still permitted in dog foods.

Vitamin C (ascorbate) and Vitamin E (mixed tocopherols)

These are both natural preservatives. Dog foods containing Vitamin C or E will have a shelf life of six months, which is about half that of a food containing artificial preservatives.

Oils of rosemary, clove, or other spices

Spice oils are less commonly used but can also serve as a natural preservative, meaning that the food's shelf life will be about six months.

It is important to note that a food may be advertised as having "no added artificial preservatives", they may still contain low levels synthetic preservatives that previously existed in the meat or vitamins purchased from suppliers.

Photo of by-products being rendered / starkfoodsystems.com

Some of the ingredients found in dog food are the result of rendering. So, what exactly is this?

The process of rendering:

This process converts animal parts deemed unfit for human consumption into a form acceptable for use in pet foods.

The animal materials are ground before being cooked at a temperature between 220° and 270° F for up to an hour. After being cooked, the mixture is then spun at a high speed to remove the grease and tallow. The removed material is then added to pet food and listed as animal fat on the ingredients label.

The mixture that remains after the grease is removed is then dried. This becomes the meal product in many pet foods.

Are meals bad?

"Good meals" include those of obvious origin. Ingredients such as "lamb meal", "beef meal", and "chicken meal" have all been rendered and provide quality nutrition in a dog food.

An ingredient of lower quality is "chicken by-product meal", which contains rendered chicken products, including necks, feet, intestines, and undeveloped eggs.

The ingredient of highest concern is "meat and bone meal" as this can contain the undesirable products listed above, including euthanized animals, diseased animal tissue, flea collars, etc.

To learn more about meals and what is rendered, click here.

Photo: Clextral.com

When opening the can, ripping the bag, or browsing the aisles of the pet store, do you ever wonder how pet food is made? How do some companies create a potpourri of bones, circles, and triangles?

Dry Food

First, the animal ingredients are added to a large vat. This may include quality ingredients such as beef, lamb, or chicken meat. Or, ingredients may be comprised of horses, euthanized pets, by-products, etc. All material is then ground, cooked at a temperature between 220° and 270° F for up to an hour, then spun to remove the fat in a process called rendering.

The rendered material is mixed with cereal grains, flours, meat or bone meal, etc. to gain the desired consistency. Preservatives may also be added at this time. This doughy material is fed into a machine called an extruder where it is subjected to high heat and pressure and squeezed through a mold. As the substance exits the mold, a spinning blade rapidly cuts the strand of dough into small pieces.

The hot doughy pieces are exposed to normal air pressure which causes them to expand or "puff" into the intended shape. After it dries, many manufacturers will spray the food with animal fat, sweeteners, or other flavor agents, known as "digests" to increase palatability.

After the food cools, it is ready to be bagged.

Some dry foods are not extruded. Instead, they are cooked at a temperature of at least 500° F. A hard, crunchy "sheet" is formed which is then broken into several irregular pieces. Generally, food produced in this manner does not need added digests as the food is relatively palatable.

Although most bacteria is killed during the heating process, the food can become contaminated during the cooling and coating process before it is packaged. For this reason, some experts caution pet owners against wetting dry food with canned food, water, milk, etc. When the liquid is applied, bacteria may multiple on the food's surface causing pet illness.

Wet Food

The food's ingredients are combined and ground. A special extruder may be used to form chunks, if necessary.

Many companies cook their food before canning. The cans make their way into a heating chamber, also called a retort. They are exposed to 250° F for about 80 minutes to sterilize the cans. Some food manufactures actually cook their food in the can during this process.

The canned food is then cooled quickly and dried. The containers are now ready for labeling and packaging.

Chicken meal, lamb meal, and by-product meal are all examples of dog food ingredients. But, what is "meal", really?

The Food and Drug Administration (FDA) defines meal as "the rendered product from mammal tissues, exclusive of any added blood, hair, horn, hide trimmings, manure, stomach and rumen contents." 

Meal is produced through the process of rendering in which ingredients are ground, boiled, spun to remove the fat, and dried. After rendering, only about 10% water remains allowing the end product to consist largely of minerals and protein (about 50 - 65% protein).

While they can be an excellent source of nutrition and protein, not all meals are created equal.

When describing meal as an ingredient in dog food, the FDA's website states: "In addition to the processing, it could also contain parts of animals one would not think of as 'meat.'"

Source-listed meals

Generally speaking, a "quality meal" is one for which the source of the ingredient is clearly listed, such as "lamb meal", "fish meal", and "chicken meal". Below are the Association of American Feed Control Officials (AAFCO) definitions of these ingredients:

Lamb meal: "The rendered product from lamb tissues, exclusive of blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents except in such amounts as may occur unavoidably in good processing practices."

Fish Meal: "The clean, dried, ground tissue of undecomposed whole fish or fish cuttings, either or both, with or without the extraction of part of the oil."

Chicken Meal: Chicken which has been ground or otherwise reduced in particle size."

Chicken is defined as: "The clean combination of flesh and skin with or without accompanying bone, derived from the parts or whole carcasses of chicken or a combination thereof, exclusive of feathers, heads, feet and entrails"

By-product meals

The AAFCO defines a meat by-product as: "The non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially defatted low temperature fatty tissue, and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hoofs. It shall be suitable for use in animal food. If it bears name descriptive of its kind, it must correspond thereto."

The most commonly used by-product meal is defined below by the AFCO:

Chicken By-Product Meal: "Consists of the ground, rendered, clean parts of the carcass of slaughtered chicken, such as necks, feet, undeveloped eggs and intestines, exclusive of feathers, except in such amounts as might occur unavoidable in good processing practice."

As a rule of thumb, it is best to steer clear of by-products in your dog's food, whether as a meal or other ingredient.

Vegetable and Grain Meals

Grain and vegetable meals are generally used in dog food to keep the cost of production low. Manufacturers use products like corn gluten meal or soybean meal as an alternative to a more costly and higher quality ingredient.

Soybeans, linseed, and corn may appear as meals in pet food. However, none of these grains are easily digested and are classified as fillers.

Corn gluten meal in particular is commonly used and is a concentrated form of protein that is very difficult to digest. Using this type of ingredient allows the food to advertise high protein content even though your dog might not actually digest or benefit from any of it.

Meat and bone meals

This is the ingredient of highest concern when listed on a dog food.

Below is the AFCO definition:

Meat and Bone Meal: "The rendered product from mammal tissues, including bone, exclusive of blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents, except in such amounts as may occur unavoidably in good processing practices."

The following is a list of some (not all) ingredients that may be included in the creation of meat and bone meal.

• Tissue from slaughterhouses, including blood, feathers, heads, feet, bones, and entrails
• Restaurant grease and butcher shop trimmings
• Road kill animals, including pets, deer, raccoons, snakes, opossums, foxes, etc.
• Euthanized animals from zoos, vet clinics, or animal shelters, including cats and dogs
• Diseased animals, including those with Chronic Wasting Disease or "Mad Cow Disease"
• Tumor-ridden, cancerous, or "wormy" tissues
• Animal tissues containing drugs or pesticides and injection sites
• Flea collars, ear tags, Styrofoam, and meat wrappers

Ann Martin states in her book, Food Pets Die For: Shocking Facts About Pet Food:

"Pet Food Industry magazine states that a pet food manufacturer might reject rendered material for various reasons, including the presence of foreign material (metals, hair, plastic, rubber, glass), off odor, excessive feathers, hair or hog bristles, bone chunks, mold, chemical analysis out of specification, added blood, leather, or calcium carbonate, heavy metals, pesticide contamination, improper grind or bulk density, and insect infestation.

Please note that this article states that the manufacturer might reject this material, not that it does reject this material."

An Example:

Below is the ingredient list for PEDIGREE® WITH LAMB & RICE™ Food for Dogs. Notice that two of the first four most prevalent ingredients include a by-product meal and meat and bone meal. Also included in the top five ingredients are two fillers (Ground Whole Corn and Ground Wheat) and Animal Fat (what is spun off the ground and boiled mixture during rendering) preserved with two artificial and potentially hazardous preservatives. Later in the list are more fillers and artificial colors.

Ground Whole Corn, Chicken By-product Meal, Ground Wheat, Meat And Bone Meal, Animal Fat (preserved with BHA/BHT), Wheat Flour, Rice, Lamb, Corn Gluten Meal, Natural Flavor, Salt, Potassium Chloride, Dicalcium Phosphate, Vegetable Oil (source of Linoleic Acid), Caramel Color, Dried Beet Pulp, Titanium Dioxide, Vitamins (Choline Chloride, Dl-alpha Tocopherol Acetate [source of Vitamin E], L-ascorbyl-2-polyphosphate [source of Vitamin C*], Vitamin A Supplement, Thiamine Mononitrate [Vitamin B1], Biotin, D-calcium Pantothenate, Riboflavin Supplement [Vitamin B2], Vitamin D3 Supplement, Vitamin B12 Supplement), Minerals (Zinc Sulfate, Zinc Proteinate, Copper Sulfate, Copper Proteinate, Manganese, Proteinate, Potassium Iodide), Added FD&C and Lake Colors (Yellow 6, Yellow 5, Blue 2, Red 40.)

The Lesson

Know what's in your dog's food and always read the ingredient list on any pet food. For the most part, a meal with the source listed is a good source of nutrition. By-product meals and those of uncertain origin (including meat and bone meal) are poor ingredients and do not come highly recommended to feed to your dog.