Linda P. Case
Linda Case, MS is a trainer, canine nutritionist and owner of AutumnGold Consulting and Training Center in central Illinois. She is the author of Dog Food Logic and other books, and blogs at The Science Dog.
Wellness: Food & Nutrition
Become a label sleuth and improve your skill at making wise dog-food choices.
May 29 2014
When selecting a new dog food, take a few moments to read and compare the label claims on a variety of different brands. You may notice two things. First, many of the claims are identical, making it impossible to differentiate one brand of food from another in a meaningful way. Popular and frequently used claims promote a food’s natural properties (labels are overrun with these), as well as inclusion and exclusion of various components. Many of these claims are either not helpful at all or of limited aid in the pet food selection process.
Second, you will also notice a proliferation of health-related claims (just as you see more of these on many human foods). Commercially available dog foods not only make the hefty assertion of providing complete and balanced nutrition for your dog’s stage of life (or even for all of his stages of life), they also may purport to do the following: boost your dog’s immune system, keep his joints healthy and mobile, slow the signs of aging, support his cognitive function, keep his waistline trim, make him smarter (if he is a puppy), and promote efficient digestion.
Here is some information about certain types of label claims that can help you differentiate among brands as you review labels and evaluate foods, as well as additional information that, at least in my humble opinion, should be included on pet food labels but rarely is (a girl can dream, can’t she?).
Inclusion claims that can be helpful to consumers are those that identify specific types of protein or carbohydrate sources, the type of fat and fatty acids in the food (e.g., inclusion of omega-3 fatty acids from fish oil), the inclusion of organically grown plant ingredients or humanely produced animal-source ingredients, and the inclusion of locally or regionally sourced ingredients.
Inclusion claims that are less helpful in differentiating among products are those that make claims about the food containing antioxidants (all processed dry foods must include antioxidants to prevent rancidity), essential vitamins and minerals (again, they’ve all got ’em), or “Contains fiber for gastrointestinal health” (a balanced and complete diet should contain fiber, usually about 3 to 6 percent, so this doesn’t help you differentiate between good and not-so-good foods).
As a rule of thumb, new feeding trends, most of which have little or no scientific evidence, arrive on the scene in the pet food market a few years after they show up in the human marketplace. Recent examples include the Atkins Diet (high protein, low carbohydrate dog foods); gluten-free diets (gluten- and grain-free pet foods); probiotics in yogurt (as supplements and incorporated into dog foods); and one unique to pet foods, the “no fillers” claim, an essentially nonsensical term.
Exclusion claims that may be helpful to some owners when selecting a food include those of no genetically modified organisms (GMOs), no animal products that were treated with antibiotics or growth hormones, and no artificial antioxidants (BHA, BHT or ethoxyquin). Selection of products that purposely exclude these things generally comes from a life philosophy of reducing the consumption of highly processed or treated foods. These can be legitimate choices, provided that the purported health benefit claims are limited to those that have actual evidence.
Although there is no published evidence of health benefits associated with consuming less-processed foods, there is legitimate evidence (beyond the scope of this consideration) for environmental benefits and animal welfare benefits associated with these choices. However, this differs fundamentally from making statements that feeding these items causes dietary insufficiencies or disease in dogs. There is simply no evidence for such claims, and they should not be made in good conscience.
The bottom line with inclusion/exclusion claims is that they can provide a way for dog owners to choose a food that contains something they are looking for or that excludes something that they wish to avoid feeding their dog. Nothing wrong with that. There are many ways to feed a healthy diet and, just as with humans, many different ingredients and foods that can be fed to our dogs to keep them healthy and happy. Problems arise, however, when dog owners, not the pet food companies (notice that labels make no health claims about exclusion/inclusion items) take this a step further and make unsubstantiated claims about why the ingredients they seek are preventing disease or the ingredients they are avoiding cause disease. Just as label claims may be misleading—though they have AAFCO and the FDA’s Center for Veterinary Medicine to reprimand them if they get out of line—so too can the claims of dog owners, many of whom are quite vocal and have blogs, and don’t have to worry about satisfying a regulatory agency.
Digestibility Claims (Allowed, but Rarely Provided)
Since this is clearly a lot to ask of a single processed food, I think we are justified as dog owners to demand that the food’s ingredients are sufficiently available (i.e., are digested and absorbed) to nourish the dog. As a food property, digestibility is more important for dogs than for humans because humans generally consume a wide variety of foods, all of which vary in degree of digestibility and nutrient availability. This mix of foods and the nutrients that they provide can be expected, in most cases, to nourish us and provide the essential nutrients that our bodies need. Conversely, most dog owners feed their dogs a single food over a period of months or years. In this situation, measures of that food’s ingredient quality and digestibility become vitally important. And pet food companies correctly teach us that one of the best measures of ingredient and diet quality is a food’s digestibility.
The reason for this is that a food’s overall digestibility (called “dry matter digestibility”) is increased by the inclusion of high-quality ingredients and decreased when poor-quality ingredients are used. In addition to dry matter digestibility, which gives you a sense of the entire food’s quality, we can also measure the digestibility of the protein in the diet, since this too varies dramatically among different protein sources, with high-quality proteins being much more digestible than low-quality proteins.
In addition to the quality of ingredients, other factors that influence a food’s digestibility include processing care and handling, cooking temperatures, and storage procedures. When a finished product’s digestibility is measured, all of these factors will influence the results. Obviously, this is a very important measure, and one that could provide valuable information to pet owners, if they were privy to it.
This is where things get weird. The vast majority of pet food companies do not report digestibility values either on their food labels or in supporting materials. Some pet food industry folks will argue that these values are not reported because AAFCO has not yet established a standard protocol for digestibility studies to produce these values. This is a convenient but untenable excuse, seeing that apparent digestibility is measured using standard protocols both in academic and industry studies and is regularly reported in published research papers. Moreover, many companies (not all, unfortunately) regularly conduct digestibility trials to compare the quality of their products to that of their competitors, although these data rarely make it into the public realm. There is simply no defensible reason that this information is not made readily available to dog owners, especially given the propensity of pet food manufacturers to make claims such as “highly digestible,” “easily digested,” and “high-quality ingredients” on their labels and websites.
Here is the science: a food’s digestibility—technically, “apparent dry matter digestibility”—is most effectively measured by a feeding trial. The selected food is fed to a group of dogs for a standard period of time during which intake (amount consumed) and excretion (the amount in the fecal matter) are carefully measured. Dry matter (the entire food) and nutrient (protein, fat and so forth) digestibility are determined by subtracting the amount excreted from the amount consumed and calculating this difference as a percent.
It is not a terribly complicated or involved test, although it does require access to dogs who are being fed the food (and only that food) and full collection of feces for a few days (no big deal to people who are used to picking up poop with their hands covered only by a thin plastic baggie). But here is the kicker: although many dog food manufacturers regularly conduct digestibility tests on their foods, they do not make this information available to the dog owners who purchase their foods. Yet, at the same time, they tell consumers that products vary significantly in digestibility and ingredient quality, and that digestibility is a good measure of a food’s quality (and that their food has high or superior digestibility and contains quality ingredients).
Although it is natural to assume that all of a food should be digested, thus the very best food would have a dry matter digestibility of 100 percent, this is not only impossible but also undesirable and unhealthy. Fecal bulk is provided by undigested food, in particular many of the food’s fiber-containing ingredients. Components of food that are not processed by an animal’s digestive enzymes make it to the large intestine, where intestinal microbes further digest them to varying degrees. This process and the microbial populations that are supported by it are essential for a healthy gastrointestinal tract in all animals, including humans. As a general rule of thumb, commercial dry dog foods with reported dry matter digestibility values of 75 or less are of very poor quality, those with values of 75 to 82 percent are of moderate quality and foods with a dry matter digestibility of greater than 82 percent are high quality.
In general, raw diets that contain little starch will have digestibility coefficients (percentages) that are slightly higher than those of a dry food made with comparable ingredients. However, if the raw food contains uncooked plant starches (potato, tapioca, corn), digestibility values will decrease because of the inability of dogs to digest uncooked starch. Of course, dog owners can only make purchasing decisions based upon a product’s digestibility if they are provided this information in the first place (which they are not).
In fact, as I recently discovered, this information is denied even when a consumer requests it directly from the company. This also is a bit odd, seeing that companies promote their foods as high quality (and often as highly digestible). I contacted companies that produced more than 30 different brands of dog food and politely requested that they send me protein and dry matter digestibility values for their adult maintenance dog food. Of the 32 requests I sent, I received no response at all in 27 cases, even though many of these stated on their “request for information” pages that a response would be sent within 48 hours. Of the five responses that I received, two brands said that they do not measure the digestibility of their foods but that their foods are made from highly digestible ingredients and so are very digestible (huh?). In other words, “we do not measure it, but trust us when we tell you that our foods are really, really digestible.” Amazingly, one company even provided a value for the food digestibility that they do not measure, telling me that their foods are 85 to 88 percent digestible. (Note: Do not believe data that have not been measured.) A third company assured me only that “our foods are extremely digestible.” Only two companies of the 32 requests that I sent provided actual data, both of which fell within the range of being highly digestible. Too bad more companies are not choosing to walk their digestibility talk, even though they are more than happy to talk the digestibility talk in their claims. Bottom line: if high digestibility or quality ingredients are claimed, ask for digestibility data from the company. They should provide this information if they are making quality claims to consumers.
Ingredient Source and Manufacturer
This means that the dog food must be both sourced and produced within the United States. If more than a “negligible” amount of the ingredients are imported, then the company cannot legally make this claim. Unfortunately, neither the FTC nor AAFCO specifies exactly what percentage of a food is more than “negligible,” which leaves this regulation open for at least some interpretation. Still, if you read a “Made in the USA” claim on a pet food package, you can also assume that most, if not all, of the ingredients in that food were sourced within the U.S.
The Take-Away on Label Claims
Adapted from Dog Food Logic: Making Smart Decisions for Your Dog in an Age of Too Many Choices, by Linda P. Case; published by Dogwise Publishing. Used with permission.
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