Keep those Doggies Rollin’……Rawhide, Rawhide!

I have always hoped that someday I would find a connection between the Blues Brothers and dog nutrition. That day has come.

Rawhide, Rawhide: A dog person cannot walk into a pet supply store (or their own grocery store, for that matter) without noticing the explosion in the number of dog chews, dental devices and edible bones that are available for sale today. Some of these are biscuit or extruded concoctions containing a mixture of ingredients, while others originate from cow skin (rawhide chews) or are the left-over body parts of a hapless food animal (pig/lamb ears, hooves, and bully sticks).

If you do not know what a bully stick is, ask your mother. Better yet, ask your father.

rawhide knots    Bully Sticks   Pig ears  Hooves

Even as the selection of these items has expanded, nutritional information about them is still glaringly absent. Since all of these products are intended to be chewed slowly so that pieces or the entire produce will be gradually consumed by the dog, we should at least be informed as to whether these items are actually digested by dogs, should we not?

Are they digestible? Dry matter digestibility refers to the proportion of a food that a dog’s gastrointestinal tract is capable of breaking down (digesting) and absorbing into the body. When we talk about the digestibility of a dog food, we are primarily concerned with its nutrient value and ability to nourish the dog. However, when we are considering the digestibility of rawhide treats, chews and dental products, the concerns are different but equally important. Any portion of a chew that is broken off and swallowed will travel through the length of a dog’s gastrointestinal tract, just like any other food. And, if the dog is able to bite off large chunks or swallow an entire chew at once, that piece has the potential to cause digestive upset, impede normal gut motility, or in the worse case scenario, cause obstruction if it is not dissolved and digested as it moves along.

Recently, a team of researchers at the University of Illinois decided to examine exactly this question by comparing the digestibility of different types of dog chews.

The studies: Two studies were conducted, both using an in vitro (test tube) technique that has been validated as a measure of the digestive conditions that occur in a dog’s stomach (gastric digestion) and small intestine (intestinal digestion). The first study compared in vitro dry matter digestibilities of sample products from six broad categories of dog treats (1). All of the products that were tested were produced by Hartz Mountain Corporation and the study was funded by the company. The second study compared just two types of treats, pork skin versus beef rawhide chews (2). The researchers also measured digestibility of the pork skin chew using a feeding trial with dogs. (For an explanation of digestibility trials with dogs, see Scoopin’ for Science). The reason for not doing a feeding study with the beef rawhide chew was not explained in the paper.

Results: Together, the two studies reported several interesting differences between the digestibility of dog chews:

  1. Chews made from pig’s ears, which are composed primarily of cartilage and the protein collagen had very low gastric (stomach) digestibilities (14 %). Although these were almost completely digested in the intestinal environment (90 %), the lack of change in gastric acid means that a pig’s ear treat, if swallowed, would potentially leave the stomach intact and enter the small intestine will little change in size and consistency.
  2. Similarly, with the exception of one product, rawhide chews made from cow skin were very poorly digested in the stomach. Intestinal digestion was almost complete for one product, but others continued to have low digestibility, even in the intestinal environment. The researchers noted that feeding rawhide chews to a dog who tended to consume large pieces could increase a dog’s risk for intestinal blockage.
  3. When a pork skin chew was compared directly to a beef rawhide chew, the pork skin product’s digestibility was significantly greater than that of beef rawhide chew. After six hours, which is approximately the time it takes for a meal to begin to leave a dog’s stomach and enter the small intestine, the pork chew was more than 50 percent digested, while the rawhide was only 7.6 percent digested. This low rate of gastric break down continued even when tested up to 24 hours. After simulation of digestion in the small intestine (the major site of digestive processes in dogs), the pork skin rawhide was almost 100 % digested, while the beef rawhide reached only 50 to 70 % digestion under the same conditions. Rawhide was digested up to 85 % only when exposed to the intestinal conditions for 24 hours.
  4. When dogs were fed one pork skin chew per day along with their normal diet, the overall digestibility of the diet increased. This corroborates the in vitro results and supports the conclusion that the pork skin chews were highly digestible.

Take Away for Dog Folks:

One of the most interesting results of these studies was the finding of such a large difference between the digestibility of pork skin versus beef rawhide chews. Because some dogs consume these types of chews rapidly and swallow large chunks, the fact that pork chews but not beef rawhides are highly degraded in the stomach and are highly digestible overall, is of significance to dog owners. These data suggest that if an owner is going to feed some type of rawhide chew (and mind you, I am not advocating for feeding these types of treats), but if one was choosing and had a dog who might consume the treat rapidly, feeding a pork skin chew appears to be a safer bet than a beef rawhide chew.

Second, it is important to note that all types of rawhide-type chews are composed of collagen, a  structural protein that makes up most of the connective tissues in the body. This is true for ears, pig skin, rawhide, and yes, even bully sticks. As these data show, collagen can be highly digestible (or not). The difference most likely depends on the source of the product and the type of processing that is used, both of which vary a great deal among products.

Feeding  dog a chew that is composed of collagen, even when it is highly digestible collagen, does not a nutritious treat make. Although collagen is a very important and essential protein in the body, it is not a highly nutritious food protein because it is composed almost completely of non-essential amino acids and is deficient in four of the essential amino acids. What this means from a practical perspective is that even though certain types of rawhide chews are found to be highly digestible and safe (from a digestibility perspective), this does not mean that they are providing high quality nutrition to the dog. In fact, they do not. While this research is important for pushing the peanut forward regarding the safety of these products in terms of digestibility, effects on gut motility, and risk of blockage, we still need more information (and selection) of chews for dogs that are both digestible and nutritious.

Cited Studies:

  1. de Godoy MRC, Vermillion R, Bauer LL, Yamka R, Frantz N, Jia T, Fahey GC Jr, Swanson KS. In vitro disappearance characteristics of selected categories of commercially available dog treats. Journal of Nutritional Science 2014; 3:e47;1-4.
  2. Hooda S, Ferreira LG, Latour MA, Bauer LL, Gahey GC Jr, Swanson KS. In vitro digestibility of expanded pork skin and rawhide chews, and digestion and metabolic characteristics of expanded pork skin chews in healthy adult dogs. Journal of Animal Science 2012; 90:4355-4361.

(Note: These studies and this blog essay do not address the ongoing and well-publicized problems with chicken jerky treats and illness in dogs. That is a topic for another time, another post).


Air, It’s What’s for Dinner

Every once in a while, I read a paper that makes me scratch my head. Last week was just such a moment. The paper really needs no introduction. The title says it all: “Increasing volume of food by incorporating air reduces energy intake” [in dogs].


Let’s talk about obesity (again): If you read “Do you think I look fat in this collar?” you will remember that obesity is the most prevalent nutritional disorder in pet dogs today. Moreover, there is evidence that a substantial number of owners do not recognize overweight conditions in their dogs and even when they do, are unwilling or unable to comply with weight loss recommendations.

Stealing food


In their search to identify new approaches to weight control (preferably approaches that can be marketed into a new brand of dog food), some pet food companies have looked at the effects of diluting food calories. An example is increasing dietary fiber. This reduces the number of calories provided in a cup of food. Consuming foods that are high in non-fermentable fibers may also enhance feelings of satiety (fullness) in dogs, although the evidence for this effect is not conclusive. However, feeding high levels of dietary fiber causes increased defecation frequency and stool quantity, often producing voluminous poops that are loose and smelly, effects that most owners are not looking for in a dog food.

Recently, in their quest to find a canine version of the weight loss Holy Grail, researchers latched on to a nutrient that most of us would probably not even consider when thinking about keeping Muffin trim. (We would not consider it because it is actually not a nutrient).

Air Bites


The Study: A group of researchers at the Royal Canin Research Center, at the National College of Veterinary Medicine in France and at the University of Liverpool in the UK collaborated to study the effects of feeding a dry dog food formulated to contain more air (1). They wanted to determine if there was a satiety-producing effect of adding air to extruded kibbles, thereby increasing the volume that is fed whilst delivering the same number of calories. This is essentially a cheaper version of the “let’s add fiber to dog food to dilute its calories” approach.

To understand this concept, consider the density (weight/volume) of a cup of corn meal compared with the density of a cup of air-popped popcorn. Same food; more air in the latter than the former. As a result, the cup of popped corn will contain fewer calories and nutrients than the cup of ground corn meal. When we are talking about extruded dog food, this idea is quite easy to put into practice because varying  extrusion conditions during processing can lead to different degrees of expansion in the end product. Highly expanded kibbles contain more air pockets, will feel lighter (because they are), and will provide fewer calories per cup than a food that has the same nutrient formulation but is less expanded. Compare the two examples below:

High Density Dry Food                Low Density Dry Food

The food on the left is a very dense product and provides about 460 kcal/cup when fed to a dog. The food on the right is less dense (you can see the little air pockets in the kibbles), and provides about 320 kcal/cup when fed. (Note: Multiple factors, not only air, affect a food’s energy density. These include the food’s digestibility and fat content, among other attributes).

The Air-enhanced Food: The researchers created a test diet that was extruded to include a higher proportion of air than that which is typical. Simply expanding the kibbles to a greater degree and increasing its trapped air pockets resulted in a caloric density that was about half that of the control food. The control diet was a food that contained the same ingredients and nutrient profile, but less air. The researchers conducted three feeding trials:

  • Experiment 1 measured the length of time that it took dogs to consume a meal that contained  increasing proportions of the test diet while still providing the same number of calories. Therefore,  because the test food contained less than half of the calories per cup than the control food, the amount of food that was fed more than doubled when the test diet was fed exclusively. Results: Not surprisingly, it took dogs longer to eat the larger meals of air-enhanced food than it took them to eat the smaller volume of food that they were given of the control diet. (In other words, it took the dogs longer to eat, um……more food). Although this sounds obvious, there is some evidence (in human subjects) that slowing down the rate of eating while consuming the same number of calories enhances satiety by increasing the release and effects of satiety-inducing and appetite-suppressing hormones.
  • Experiment 2 fed the test food and the control food to a group of 10 adult Beagles and used a standard procedure used to measure satiety. This methodology involves offering dogs more food than they are expected to eat in sequential meals spaced one hour apart (kinda like “first breakfast and second breakfast” for Hobbit fans).  Results: Adding air to food slightly enhanced feelings of satiety in dogs. This means that the dogs consumed a bit less food each day (and fewer calories) of the air-enhanced food when allowed to eat all that they desired than they did of the control food. This effect is similar to the expectation that consuming a high fiber food will lead to making one feel a bit more full and subsequently to consuming less food overall.
  • Experiment 3 used the same protocol as Experiment 2 and compared the satiety-inducing effects of the test diet with a commercially available adult maintenance dog food. The commercial food provided more than 3 times the calories per cup as the test, air-enhanced food. Results: The results were similar to those of Experiment 2. Adding air (lots of it, by comparison) to a food moderately enhanced feelings of satiety in the dogs. I envision a group of over-stuffed Beagles, burping politely (and repeatedly….it is air after all), and saying “Really. No. I couldn’t eat another bite”.


The researchers concluded: “….results from the present study indicate that incorporating air into food provides a strategy to reduce energy [caloric] intake in dogs and, consequently could be a useful strategy for weight management in pets.”  They also note that this study did not show whether or not dogs would reduce their intake of air-enhanced food to levels that would  lead to weight loss nor did it measure effects for more than a few days. They assure us that such research is yet to come.


Draggin’ Out the Ol’ Box: Even if it can be shown that increasing the amount of air in a dog’s food enhances satiety, do we really need such a food? If one’s goals are to reduce a dog’s caloric intake and slow rate of eating, there are already effective approaches that owners can take. We can first select a high quality food (or home prepared diet) that is well-matched to our dog’s lifestyle and activity level. If a dog gains too much weight, we can reduce the amount that is fed or switch to a food that is still of high quality but is lower in fat (i.e. less energy dense without diluting calories). Increasing exercise through daily walks, engaging in a new dog training activity or sport, or teaching retrieve or “find it” games will all burn more calories and help increase a dog’s fitness level.

What about satiety? Is it true that feeding a larger volume of food or slowing the rate of eating will help our dogs to feel more satisfied? Perhaps. There is certainly some evidence to support this theory.  However, while the hormonal changes associated with a slower rate of eating may enhance feelings of satiety, do we really need to inject air into our dog’s food to accomplish this? Many owners spread out their dog’s daily meal time by using a food delivery toy that their dog enjoys or feed using a “slow” bowl that is constructed to make the dog work a bit harder for his food. Feeding multiple small meals a day or floating dry food in warm water prior to feeding can be helpful to slow rate of eating as well.

Surely, we should not be expected to view injecting air into food as the new miracle weight loss approach for dogs. Are we really destined to see a new brand of dog food on the shelves selling under the marketing slogan of “Let Them Eat Air“? 

Skeptical Dog

Cited Study: Serisier S,Pizzagalli A, Leclerc L, Feugier A, Nguyen P, Biourge V, German AJ. Increasing volume of food by incorporating air reduces energy intake. Journal of Nutritional Science 2104; 3;e59:1-5.


Scoopin’ for Science

I was at the gym recently, swimming laps. After my work-out, I was sitting by the side of the pool and a fellow swimmer and friend stopped to chat about dogs. He has never owned a dog, but his daughter has been pressuring him and he thinks she is finally old enough to take on the responsibility of caring for a dog (good dad!). So, I was anticipating a discussion about breeds, where to look, training, feeding, etc. That is not where this was going at all. Instead, he wanted to talk about poop:

Me: “So, does she have a breed or breed-type that she is considering?”

Him: “No…..not yet. What I really want to ask you about is……the poop thing.”

Me: “Um…..what?”

Him: “You know. I see all of the people in our neighborhood taking their dogs for a  walk in the morning and they all carry these bags with them and then, ugh…..they all PICK UP THE POOP WITH THEIR HANDS!!!!”

Me: “Well, not exactly; there is a plastic baggie involved. But regardless, what is your point?”

Him: “I just find that so gross and disgusting. I don’t think I could do it.”

Me: “Wh…What???”

Him: “Ick. Yuck.” (Accompanied by a squeamish expression that I have never seen on the face of a grown man).

Me; “Okay, let me get this straight. You are a triathlete. You regularly beat the crap out of your body by swimming, running and cycling ridiculously long distances. You have backpacked and camped all over the country, with no “facilities’ and sometimes not bathing for days……and you squirm at picking up dog poop in a plastic baggie?”

Him: “Yeah, that about covers it.”

Me (laughing): “You gotta get over that dude. Take a class or something. All dog folks pick up poop. It’s no big deal.”

Him: “Hmmm…..” (not buying it).

Baggie poop

It really is no big deal. Many dog owners are not only comfortable with poop scooping, we also regularly examine the quality of our dog’s leavings as a general barometer of their health and the quality of the food that we are feeding.

So, when I learned of a recent study that asked a group of dog owners to do some “poop scoopin’ for science” I was only surprised that there have not been more studies of this nature published in the past.

The Issue: Those of you who have read Dog Food Logic know that I personally advocate for increased transparency in the pet food industry and for the need to provide dog owners with information that is actually useful to us when selecting foods. Without question, one of the most important measures of  a food’s quality is its digestibility – the proportion of the food that a dog’s gastrointestinal tract is able to actually break down (digest) and absorb into the body for use.  Digestibility correlates well with both ingredient quality and proper food processing techniques, so this information would be very helpful for dog owners to have. However, the vast majority of companies do not provide it. The only (very rough) estimate of food digestibility that we have is that gleaned by regularly examining the quality and quantity of our dog’s feces. A behavior that, in addition to providing very little real information, lends itself to weird looks from neighbors such as my swimming friend. A crappy state of affairs, indeed.

Industry’s Position: When challenged, representatives of the pet food industry generally deflect criticism by maintaining that current AAFCO regulations do not require reporting of food digestibility. (The old “we don’t gotta so we ain’t gonna” defense). Further, not all pet food companies regularly measure digestibility because doing so requires them to conduct feeding trials with dogs which in turn requires access to research kennels and laboratories. Such studies are expensive and may be cost prohibitive for some of the smaller companies that do not maintain their own kennels or in-house analytical laboratories.

Fair enough. However, what about using dogs who live in homes? Why not enlist everyday Citizen Scientists who are dedicated to their dogs, feed commercial dog food, are concerned about quality, and who do not squirm at picking up dog poop? Not only would this lead to increased numbers of dogs enrolled in these trials (thus supporting improved accuracy of digestibility estimates), it would also allow needed comparisons among breeds, ages, life styles and activity levels of dogs, and could get information about food quality out to the consumers who need it. Another definite advantage of in-home studies is that they lead to reduced need for kenneled research dogs, a clear animal welfare benefit.

Happily for us, a group of researchers from two universities in The Netherlands were thinking the same thing (1).

The Study: The objective of their study was to develop a simple method of measuring dog food digestibility that could be used with privately owned dogs living in homes. They recruited a group of 40 adult, healthy dogs and asked their owners to feed a test food (and nothing else) for a period of 7 days. Amounts to feed each dog were pre-measured and the volume the dog consumed each day was recorded. In this study, the test diet was a commercial dry (extruded) food formulated for adult dogs. After seven days of feeding, the owners were asked to collect all of their dog’s feces for a period of 24-hours. The feces were frozen and submitted to the researchers for analysis.

Here is a flow-chart showing how a digestibility trial works. It is conducted in the same manner with kenneled dogs, although feeding and feces collection periods can vary:

Digest Trials

Results: The owners recorded the amount of food that their dog consumed each day and collected all of their dog’s feces over the final 24-hours of the study. The researchers then analyzed the nutrient content in the food that was consumed and in the feces that were excreted. From these data, they calculated the proportion of the food that each dog digested, called a “digestibility coefficient” and average values for the entire sample of dogs. In this experiment, the food’s dry matter digestibility was 77.4 % and its protein digestibility was 77.7 %, values that reflect a food of “low to moderate” quality. The variability between dogs (as reflected by the standard errors), was found to be low. This suggests that the dogs in the trial showed consistency in their ability to digest the food and supports the in-home trial as a valid procedure. In addition, the study reported compliance in 39 out of 40 homes, demonstrating some pretty dedicated poop scooping.


Up on the ol’ Box: Another recent study evaluated a set of eight commercial dog foods using both nutrient analysis and a set of feeding trials like the one above, but with kenneled dogs (2). They found a very wide range in the overall (dry matter) digestibilities and protein digestibilities among the eight products and noted that these differences would not be reflected by information that was provided on the pet food labels. The authors went even further, stating: “…we have to note that there is no comprehensive list of information available to the consumer to evaluate the quality of commercial diets. A combination of laboratory analyses and estimation of digestibility coefficients is the only way to perform an accurate and complete evaluation of the quality of a commercial diet”  And yet, not all pet food companies supply complete nutrient levels for their foods and no pet food companies regularly provides digestibility coefficients to dog owners.

The results of this pilot study tell us that in-home studies with owned dogs can provide needed information about dog food quality and can allow the study of factors that may influence how well dogs utilize different foods, such as age, breed, size, health status and activity levels. Compliance was very good; these owners were willing to do their part, scooping poop for science. Now all that we need is for pet food companies to step up and begin to conduct in-home studies and make the information that they provide available to the dog folks who care.

Cited Studies:

  1. Hagen-Plantinga EA, Bosch G, Hendriks WH. Practical approach to determine apparent digestibility of canine diets. Journal of Nutritional Science 2014;3;e31:1-4.
  2.  Daumas C, Paragon BM, Thorin C, Martin L, Dumon H, Ninet S, Nguyen P. Evaluation of eight commercial dog diets. Journal of Nutritional Science 2014;3;e63:1-5.





“Dog Food Logic” Wins Maxwell Award!

My publisher, Dogwise, informed me last week that my book “Dog Food Logic: Making Smart Decisions for your Dog in an Age of Too Many Choices” has won the Dog Writer’s Association of America’s Maxwell Award for Best Health Care Book of 2014! For more information about “Dog Food Logic” and about my newest book “Beware the Straw Man” click the links below.

dog-food-logic-cover-final               Beware Straw Man Cover

“Do you think I look fat in this collar?”

Said no dog. Ever.

This is how dogs more likely consider the possibility of being overweight:

Fat Sounds Awesome

Most owners are aware that it is our responsibility to keep our dogs at a healthy body weight and in good condition. We all know this, right?

Perhaps not. A few statistics:

  • Obesity continues to be the number one nutritional problem in pet dogs in the United States.
  • According to the Association of Pet Obesity Prevention (APOP), veterinarians classified 53 percent of their canine patients as either overweight or obese.
  • In the same survey, only 22 percent of the owners identified their dog as being overweight.
  • APOP founder Dr. Ernie Ward refers to this cognitive disconnect as the “fat pet gap”. He suggests that American dog owners’ perceptions of what is normal in their dogs has been gradually distorted, leading to the perception that an overweight body type is normal.
Two Fat Labs


Why the Disconnect? A common theory used to explain the mismatch between what owners perceive and what their dog actually looks like is that owners simply have not been taught how to recognize a fat dog and lack the knowledge to differentiate between a dog who is at ideal weight versus one who is slightly (or more) overweight. In an attempt to counteract this problem, pet food companies created Body Condition Scores. These are standardized five to 9-point visual scales designed to help owners and veterinarians correctly assess a dog’s body condition. Here are two examples:

5 point BCS         Purina BCS

Problem solved? These scales have been around for more than 15 years. Yet, our dogs are still fat. Perhaps the scales are not being used? Are they difficult to understand? Recently a group of researchers asked the question: “If we give dog owners a BCS tool, show them how to use it, and then ask them to evaluate their own dog using the tool, will their assessments improve?”  Their hypothesis was optimistic. They believed this would do the trick.

The Study: This was a pre-test/post-test study design and included a group of 110 owners and their dogs (1). In the pre-test portion of the study, the owner was asked to assess their dog’s body condition. No guidance was provided and the owner was required to select the word that best described their dog from a set of five terms; very thin, thin, ideal weight, overweight, or markedly obese. Following this assessment, the owner was provided with a five-point BCS chart that used the same five descriptors along with visual silhouettes and descriptions. They were given instructions of how to use the chart and were then asked to assess their dog a second time. The investigating veterinarian also assessed the dog using the BCS chart and physical examination.

Results: Several interesting (and surprising) results were reported:

  1. Prior to using the BCS chart, 2/3 of the owners (66 %) incorrectly assessed their dog’s body condition. The majority underestimated body condition, believing their overweight dog to be at or near his or her ideal weight. These results are consistent with those reported by other researchers and with the APOP survey.
  2. Following training with the BCS tool, these misperceptions persisted, showing virtually no change; 65 % were incorrect and only 15 % of owners changed their original score (some up/some down, and some from correct to incorrect!). The majority of owners continued to see their plump dog as being at his or her optimal weight.
  3. Here is where things get really weird.
    • When queried, the majority of owners (77 %) stated that they believed that using the BCS chart had significantly improved their ability to estimate their dog’s body condition (huh?). This statement was made despite the fact that only 17 owners changed their scores after they learned to use the chart.
    • And, those who believed the chart had helped them fared no better in post-test success than the those who believed that the chart did not help them.

Get Fuzzy Fat Sachel

Take Away for Dog Folks: This study confirms what several other researchers have reported and what the APOP statistics tell us; dog owners tend to underestimate their dog’s weight and body condition, seeing a dog who is overweight as ideal. It also goes an important step further. Even when owners are shown how to identify an overweight dog, they are literally blind to seeing the evidence in their own dog. We still get it wrong. Why is this happening? There are a few possible reasons:

  • Fido is not fat; he just has big bones: Resistance to seeing one’s own dog as overweight may be a form of denial, similar to the well-documented misperception  that many parents have regarding their child’s weight. Because being overweight is viewed negatively by others, is associated with well-known health risks, and may be perceived as reflecting badly upon a dog owner’s ability to care properly for their dog, denial may be quite an attractive alternative to the truth. 
  • Confirmation bias: In this pre-test/post-test situation, people may have resisted changing their scores following training simply because, well, people hate to be proven wrong. If an owner had preconceived beliefs about his dog’s weight and initially assigned a moderate score, he might subsequently (and unconsciously) use the BCS chart to confirm that belief, however misguided it was.
  • Food is love: There are data from other studies showing that a substantial number of owners admit that they are unwilling to deny food to their dog even when they know the dog is overweight because they see feeding as an important outlet for love and nurturing (2). Similarly, owners tend to resist changing their feeding habits with their dogs even when aware of the adverse health effects of being overweight (3).


Soap Box Time: The results of this study are not encouraging and suggest that we have a long way to go regarding our ability to prevent and reduce overweight conditions in dogs. If you are a trainer, doggy day care owner, groomer, veterinarian, veterinary technician, or other pet professional who works daily with dog owners and their dogs, perhaps it is time for a little “tough love”. Post a BCS chart in your facility, have a weight scale handy, and don’t be afraid to use them. Call the fat dogs fat…….nicely of course and with great respect for their owners (the dogs won’t care; they will be proud). Help owners to face reality.  Provide guidelines to help dogs to trim down, encourage exercise for both the dog’s body and mind, and help people to understand that keeping a dog trim is one of the best ways that we can support their health and demonstrate our love.

Cited Studies:

  1. Eastland-Jones RC, German AJ, Holden SL, Biourge V, Pickavance LC. Owner misperception of canine body condition persists despite use of a body condition score chart. Journal of Nutritional Science 2014; 3:e45;1-5.
  2. Kienzle E, Bergler R, Mandernach A. A comparison of the feeding behavior and the human-animal relationship in owners of normal and obese dogs. Journal of Nutrition 1998; 128:2779S-2782S.
  3. Bland IM, Guthrie-Jones A, Taylor RD. Dog obesity: Owner attitudes and behavior. Preventive Veterinary Medicine 2009; 92:333-340.

What’s in YOUR Food?

What I mean of course, is “What’s in your dog’s food?”

When asked this question, most owners read the list of ingredients found on their food’s label. By law, pet food ingredients must be reported in descending order of preponderance by weight at the time of processing. This means that ingredients that are found first in the list are present in greatest abundance in the food.

There are a number of limitations regarding the type of information that a pet food ingredient list provides to consumers; most of these are detailed in my book Dog Food Logic. However, until recently, it was generally presumed that misrepresenting food ingredients, for example listing an ingredient that is not actually present in the food or failing to identify others, was not one of those limitations. Unfortunately, such a presumption may be ill-founded.

Several research studies published in the scientific literature over the past four years have shown that at least some brands of commercial dog foods have ingredient lists that do not always conform to what is actually in the food.

Study 1:  Four brands of dry dog food that are marketed as novel protein source diets containing venison were tested for the presence of other protein sources (1). Of the four products, two listed chicken and one listed rice protein in addition to venison on their label ingredient panel. Results: Of the four foods, three tested positive for the presence of soy protein and one tested positive for the presence of beef protein. In all of these cases, neither beef nor soy products were reported in the product’s ingredient list. (It is interesting and somewhat ironic to note that one of the foods that tested positive for soy protein carried a front label claim stating “No Soy!”). 

Study 2: The same team of researchers tested four retail dry dog foods that carried a “No Soy” label claim and seven therapeutic dry foods marketed to veterinarians for use in diagnosing soy allergies in dogs (2). Results: Soy protein was detected in three of the four retail brands.  Of the seven veterinary-prescribed foods, four were found to contain low levels of soy protein.

Study 3: Eleven limited ingredient diets (LIDs) and one veterinary-prescribed hydrolyzed protein food were tested for the presence of animal origin ingredients not reported on their ingredient label (3). This study used DNA analysis and microscopic analysis of food particles that allowed the distinction between mammal, fish, and bird tissues. Results: Of the 12 products, the species of animal identified by microscopic and DNA analysis matched the food label’s ingredient list in only two. In the remaining 10 products, bone tissue fragments from one or more unreported animal source proteins were present.

Study 4: Most recently, a comprehensive study published in the journal Food Control examined the content of 52 brands of commercial dog and cat food using DNA analysis. Results: Of the 52 products, 31 (60 %) had no labeling violations, meaning that the protein ingredients that were reported in the ingredient list completely matched the sources that were identified via DNA analysis. However, 21 brands (40 %) contained protein sources that were not listed on the ingredient list or in one case, a protein source that could not be identified. In three of these products, the protein source listed on the ingredient panel was entirely absent from the food. Chicken was the most commonly undeclared protein source in the mislabeled foods. This is not surprising because chicken is generally the least expensive source of animal protein in pet foods. Mislabeling was also more frequently observed in canned (wet) pet foods than in dry pet foods. The presence of goat meat (yes, you read that correctly) was found in 9 products. Seven of these identified another animal species source such as chicken or beef on their label and did not include the more generic “meat” term nor (obviously) “goat meat” as an ingredient.

Mystery Meat 2

Is there any goat in that?

Take Away for Dog Folks: The authors of the first three papers wrote that their objectives were to examine LIDs for the presence of undeclared protein ingredients. Their concern was the increased use of these foods by owners and some veterinarians to diagnose food-related allergies in dogs. If you are not familiar with it, the standard diagnostic approach when food allergy is suspected is to feed a food that contains a single and novel (or hydrolyzed) protein source to the dog for 8 to 10 weeks. This is called an elimination diet and its purpose is to prevent exposure to all potential food allergens. If a dog’s signs diminish, the elimination diet trial is considered positive for adverse food reaction (food allergy) and an attempt is made to identify protein sources that the dog can tolerate. The scientists’ concern was that owners were unwittingly using the LIDs as an alternative to the more expensive and supposedly better controlled veterinary-prescribed foods. The expectation was that the therapeutic foods would contain only what their labels claimed, while the retail LIDs would be contaminated with other ingredients. What they found however, was that both retail foods and veterinary-prescribed foods have the potential to be mislabeled. (Oops).

Regardless of results not always showing what one expects, there are several important issues that these studies expose:

  1. Intentional or accidental? The analytical tests used in these studies are able to detect very small quantities of undeclared protein sources. Therefore, a positive result does not necessarily mean that the source was contributing a large proportion of the food’s protein. It only means that an undeclared protein source was present. This might occur accidentally as a result of ingredient cross-contamination during transportation, via airborne particle transfer in the manufacturing plant, or through the use of equipment that was not thoroughly cleaned between production runs. Regardless of intent, these causes are still problems and should be addressed in good manufacturing practice and quality control procedures. Alternatively, the identification of chicken as the most frequently undeclared animal protein source certainly suggests the potential for intentional substitution and mislabeling, seeing that chicken is less expensive than the ingredients that it augmented or replaced. Because these studies did not investigate the quantities of undeclared ingredients or whether or not their presence was intentional, these are questions that still need to be answered. 
  2. Diagnosing/managing allergic dogs: For those who live with dogs suspected of having a food allergy, these results are bad news regardless of knowing quantities or intent. Although the concentration of a food allergen that is needed to trigger an allergic response in dogs is not known, it is expected to be similar to that in people – very low. These studies suggest that feeding a veterinary-prescribed elimination diet may not be a guarantee that the dog is not exposed to a suspected allergen such as soy. In addition, feeding a dog a retail brand LID may not be an effective approach even when food allergens have been identified. For these reasons, some veterinarians and nutritionists recommend feeding a homemade elimination diet for the diagnosis of food allergies in dogs. Once the allergenic protein is identified, extreme care will be needed during food selection.
  3. Trust: Last, but certainly not least, are the issues of food mislabeling, manufacturing integrity and consumer trust. The cases reported in the most recent study, in which listed ingredients were completely absent from some foods and were substituted with other protein ingredients, are in clear violation of AAFCO labeling regulations. The researchers of that study had purchased the sample foods from retail vendors, which indicates that these violations are occurring without detection. What is not known is whether ingredient substitutions, additions, and mislabeling are intentional or accidental or where within the production chain these adulterations are taking place. What does seem clear however, is that consumers cannot always trust the ingredient list to represent only and all ingredients that are present in the food.

What is a dog person to do?? Remember that a substantial proportion of products that were tested in these studies contained all and only those protein ingredients that their labels reported. They were not mislabeled. If you feed commercial dog food, seek out reputable manufacturers. These are the producers who provide ingredient source information, manufacturing details, safety records, and detailed product information to their consumers. Moreover, ask questions, request information, demand transparency and be a critical thinker (and consumer) for your dog so that you have a better chance of knowing what is in YOUR (dog’s) food.

Cited Studies:

  1. Raditic DM, Remillard RL, Tater KC. ELISA testing for common food antigens in four dry dog foods used in dietary elimination trials. Journal of Animal Physiology and Animal Nutrition 2010; 95:90-97.
  2. Willis-Mahn C, Remillard R, Tater K. ELISA testing for soy antigens in dry dog foods used in dietary elimination trials. Journal of the American Animal Hospital Association 2014; 50:383-389.
  3. Ricci R, Granato A, Vascellari M, Boscarato M, Palagiano C, Andrighetto I, Diez M, Mutinelli F. Identificatin of undeclared sources of animal origin in canine dry foods used in dietary elimination trials. Journal of Animal Physiology and Animal Nutrition 2013; 97:32-38.
  4. Okuma TA, Hellberg RS. Identification of meat species in pet foods using a real-time polymerase chain reaction (PCR) assay. Food Control2015; 50:9-17.

The Nature of Natural

Over the last few years, the sale of dog foods that carry a claim of natural, either embedded into their brand name or proclaimed on their front label, has exploded. According to the marketing research firm Packaged Facts, natural foods are currently the fastest growing segment of the U.S. pet food market. The sale of foods that are marketed in this way doubled between 2008 and 2012 and accounted for almost 80 percent of all new products introduced between January and August of 2014. Natural pet food sales dollars during the same period exceeded 3 billion dollars, making up two-thirds of total pet food sales.

So, what is all of the fuss about? Does a claim of “natural” mean anything for your dog or is it just one more marketing gimmick?

Natural Balance                     Natural dog food label

What natural is: The Association of American Feed Control Officials (AAFCO), the organization that sets pet food ingredient and labeling definitions, states that a pet food manufacturer can include the word natural in a product’s brand name or as a label claim if the food has been preserved using only non-synthetic (i.e. naturally-derived) preservatives. This means that the food cannot include artificially produced compounds such as  butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), or ethoxyquin. Instead, naturally-derived preservatives such as tocopherols (vitamin E), ascorbic acid (vitamin C), citric acid, and rosemary extract are used. In today’s pet food market, this is not a high bar to clear. Starting in the 1980’s, consumer pressure to eliminate the use of ethoxyquin in pet foods was followed by a general trend away from artificial preservatives. Today almost all pet food manufacturers produce at least one product line of foods that are preserved without synthetic compounds and legally carry the “All Natural” claim.

All Natural

In practice: AAFCO’s definition of “natural” is so broad that it includes nearly every single type of pet food ingredient that is currently included in commercial pet foods, with the exception of chemically synthesized vitamins and minerals. And even with these, there is a loop-hole. A manufacturer that includes these items can still use the natural moniker provided the statement “with added vitamins and minerals” is tacked onto the natural label claim.

What natural is not A pet food label claim of natural does not signify anything about a food’s quality, the source or type of ingredients that it includes, the company’s manufacturing practices, or the food’s safety record. Neither does the appearance of the word natural signify that a food is organic, that it contains no GMO ingredients, is made from human-grade or high quality ingredients, or does not contain by-products. The bottom line is that other than assuring the owner that the food does not contain synthetic preservatives, a label claim of “natural” is meaningless and provides no information that helps to differentiate among foods in terms of their ingredients, quality, digestibility, manufacturing practices or food safety.

Natural vs. organic: There is however an important distinction between the terms natural and organic. According to the USDA’s National Organic Standards Board, a food can be labeled organic if the plant ingredients that are included were grown without pesticides, artificial or sewage sludge fertilizers, or irradiation and exclude genetically modified organisms (GMOs). Animal-source ingredients must come from animals that were raised exclusively on organic feed, were not treated with hormones or antibiotics, and were housed/fed according to an agreed upon welfare standard. However, these requirements were developed for human foods and the National Organic Program (NOP) lacks the legal authority to regulate organic label claims on pet food. Pet food companies can voluntarily choose to meet the NOP standards, apply for NOP certification, and if accepted can use the USDA Organic seal. However, because certification is optional, a pet food company’s use of certified organic ingredients does not mean that the product itself is certified organic via USDA standards. AFFCO has not yet developed a regulation for organic pet foods  and recommends that pet food companies attempt to follow the USDA organic food regulations in their labeling practices. However, companies are not required to do so. If a company chooses to follow the guidelines of the National Organic Program (NOP), you should be able to tell by reading their claim and the ingredients list. If the label states “100 Percent Organic“, every single ingredient must be organic. Foods labeled simply “Organic” must include at least 95 percent organically produced ingredients. Below this level is the label claim “Made with Organic Ingredients”, for which at least 70 percent of the product’s ingredients are organic.

Cat's Poo

Why natural? Oddly enough, despite the fact that the term organic is more narrowly defined and better regulated than the term natural, it is the natural foods segment and not organic pet foods that are taking off in sales. A recent marketing research study examined these differences (1).

The Study: Marketing researchers at New Mexico State University surveyed a group of 661 U.S. dog owners regarding their pet food choices. The researchers used a research methodology called “discrete choice analysis” in which they presented participants with a panel of dog foods that varied in key attributes such as price, ingredient type, label claims, and package size and asked them to identify the food that they would choose for their dog. The objectives of the study were to test the effects of label claims such as “Veterinarian Recommended“, “Natural” and “Organic“, as well as package size, life stage formulation, and price upon dog owner preferences. Because a primary goal was to study perceptions of  natural pet foods, the participants were provided with the AAFCO’s definition of the term natural and the USDA’s definition of the term organic prior to starting the survey.

Results: Of the five primary dog food attributes that were studied, the price of the food was found to be the most important determinant of choice. U.S. dog owners were consistently interested in finding the least expensive food. Following product cost, owners focused most intently upon whether or not the food’s ingredients were promoted as being natural or organic. When these two ingredient types were compared, dog owners were willing to pay the highest (premium) price for a dog food containing a claim of natural ingredients, more so even than for a food stating that it contained organic ingredients. Other attributes such as being recommended by a veterinarian, life stage formulation, and package size were less important. Following price point, the most important driver for choosing a dog food was seeing the word “Natural” somewhere on the label or in the brand name.

Take Away for Dog Folks:  Perhaps the most important fact that dog owners should be aware of is that virtually anything goes when it comes to the “It’s Natural” claim on pet food labels. (This is also true of human foods, by the way). The only significant requirement is that a dog food labels as “All Natural” has is that it cannot contain artificial preservatives. That’s All.

Thats all folks

However, even knowing the ridiculously broad definition of the term natural, people continued to attribute great value to the term and showed that they were willing to pay a premium price to see it on their dog’s food label. In fact, this study showed that owners were willing to pay more for natural ingredients than for organic ingredients despite learning just minutes earlier about the clear differences between the two terms and the stricter guidelines for and regulation of organic foods. Make no doubt about it; this distinction is a win-win for pet food manufacturers because the cost difference between making an “All Natural” pet food claim (that means nothing) and an “Organic” claim that (though optional) is associated with set guidelines for ingredient production and sourcing, is substantial. Expect to see even more of the word natural on pet food shelves in the future.

And train yourself to ignore that word.

Pet food claims for providing superior nutrition, for promoting health, or for being safer do not follow from a claim of naturalness without evidence of such benefit. And, this is especially true when the word means nothing at all in the first place.

Natural Cheetos

Cheetos – Good for you because they contain all natural ingredients

Cited Study:

1. Simonsen JE, Fasenko GM, Lillywhite JM. The value-added dog food market: Do dog owners prefer natural or organic dog foods? Journal of Agricultural Science 2014; 6:86-97.