How Reactive is Your…….Lysine?

I imagine that the word “reactive” caused most readers to think of this:

reactive dog

REACTIVE DOG

However, what we will actually be talking about is this:

Lysine-zwitterion-2D

LYSINE – AN ESSENTIAL AMINO ACID

Yeah, not quite so dramatic, I admit. However, the reality is that the amount of  reactive lysine present in your dog’s food is much more likely to have an impact on his health and wellness than is the somewhat lower risk of meeting Mr. Crabby Pants pictured above.

The reason? Well,  its all about the protein quality of commercial dog foods –  the good, the bad, and the reactive.

Reactive lysine: Lysine is one of the 10 essential amino acids (the building blocks of proteins) that must be provided in a dog’s diet. The term essential means that dogs cannot produce these amino acids endogenously (in the body) and so they must be supplied by the protein in the food. Of the essential amino acids, lysine is rather unique in that it has a reactive amino group (the blue H3N+ in the graphic above). This group hangs out into space waving its H+ around, which is ready and able to engage and link up with other molecules. And, just as with reactive dogs, these encounters do not always end well.

When food proteins are subjected to heat treatment and other processing conditions, some of this lysine binds to certain sugars and amino acids. When this occurs, the modified form of lysine is not available, meaning that the dog is unable to use the lysine, even after it has been digested and absorbed into the body. Some of the altered lysine may be modified further to produce compounds called “advanced Maillard compounds“. Maillard products are actually quite well-known to most people – they cause the browning of the toast that you eat for breakfast, on the onions that you caramelize, and form the grill lines on your hamburger.

Maillard-reaction-graphic-062912

JUST TO BE CLEAR

Reactive lysine in dog foods: Tasty toast aside, for dogs and commercial dog foods, measures of the amount of reactive lysine and Maillard compounds provide an indication of a food’s protein quality. This goes above and beyond digestibility (which we discussed in an earlier blog, “Scoopin’ for Science“), because the amount of reactive lysine reflects the actual nutritive value of the protein once it has been digested and absorbed into the body.

Processing damages protein: The heat treatment that is used to produce commercial dog foods has many benefits – it functions to improve a food’s overall digestibility, enhances shelf life, and assures food safety. However, heat and mechanical processing can also result in damage to the food’s protein. The good news is that the degree of this damage can be measured using laboratory procedures that analyze reactive (available) lysine (RL) and total lysine (TL). A ratio is then calculated between these two values (RL:TL). A high ratio value reflects more reactive lysine, less protein damage and higher quality protein. Conversely, a low value signifies greater loss of lysine during processing, more damage to the protein, and lower quality.

Cool, right? Well, yeah. Really cool. Because measuring reactive lysine ratios provides us (dog folks) with an indication of how processing such as canning, extrusion, rendering, and even dehydration or freeze-drying, might damage food protein and reduce the overall quality and nutritional value of a dog food.

Too bad this information is never reported by pet food companies. (To date, they are not required to report any measures of food digestibility or protein quality to their consumers).

Even though pet food manufacturers are not reporting these values, a group of scientists have been.

science-header

The Study: Researchers with the Animal Nutrition Group at Wageningen University in The Netherlands have been examining reactive lysine content and Maillard reaction products in a variety of commercial pet foods. In a recent paper, they collected 67 different brands of dog and cat foods, formulated for different life stages (1). Lysine levels were measured for each, and RL:TL ratios were calculated. The researchers also compared available lysine levels in the foods to the minimum lysine requirements reported by the current NRC Nutrient Requirements for Dog and Cats.

Results: A wide range of RL:TL ratios were reported, suggesting that protein damage in commercial foods is highly variable and may not be dependent simply on the type of processing that is used:

  • Processing type vs. ingredients: Overall, as reflected by the RL:TL ratio, canned foods had less protein damage than extruded foods, which had less damage (surprisingly) than pelleted foods.  However, the range of values within processing type was very high with the three types of foods showing a lot of overlap. This suggested that source and type of ingredients may matter as much as or even more than processing type.
  • Ingredients: Many of the ingredients that are used to produce pelleted and extruded foods are pre-treated with heat, drying and grinding. For extruded foods, this refers primarily to the production of meat meals (see “What’s the Deal with Meals” for a complete discussion of protein meals). It is speculated that this processing and how well it is (or is not) controlled is the most important determinant of changes in protein quality.
  • Meeting lysine requirements: Of the foods that were examined in this study, up to 23 percent of a product’s lysine could be damaged and made unavailable to the dog. When these losses were considered while accounting for expected protein/lysine digestibility, some of the foods were expected to be at risk to not meet the minimum lysine requirement for growing dogs.

The authors conclude: “Ingredients and pet foods should be characterized with respect to their reactive lysine content and digestibility, to avoid limitations in the lysine supply to growing dogs” I would add to this that these measures should be available in some form to consumers, as a measure of the protein quality of the food that they are considering buying.

Detractors might argue that RL:TL ratio is “too complex” for consumers to process and understand. I disagree. A simple classification chart, such as “poor, moderate, and high” quality could be derived from the range of reactive lysine values that are reported. Knowing this information, along with the type and source of ingredients, would allow owners to make meaningful quality distinctions among foods.

soapbox

DRAGGIN’ OUT THE OL’ BOX

I have argued elsewhere that pet food producers should be required to provide digestibility information about their products, when requested. This is not too much to ask, seeing that manufacturer’s claims of “Complete and Balanced” promotes the feeding of their products as the sole source of nutrition to our dogs.  And now, according to the results of research coming from Wageningen University, there are additional measures of protein quality that can differentiate among poor, adequate and superior foods.

It is time to ask for more of pet food manufacturers. Measuring digestibility and reactive lysine levels of foods and ingredients provide measures of product quality that are directly pertinent to nutritive value and to our dogs’ health. Here is your chance, as your dog’s advocate, to be a bit reactive (no – PROACTIVE) with your pet food manufacturer…… Politely request this information about the products that you are buying – let me know what you hear back!

Proactive and Reactive handwritten on whiteboard isolatedCited Study: van Rooijen C, Bosch G, van der Poel AFB, Wierenga PA, Alexander L, Hendriks WH. Reactive lysine content in commercially available pet foods. Journal of Nutritional Science 2104; 3:e35:1-6.

 

Dog Food Marketing – Science Weighs In

Marketing researchers know a lot about advertising strategies that successfully increase sales. This is no less true for pet foods than it is for any other consumer goods. Some of the more obvious approaches to attracting dog owners to a particular brand are advertisements that appeal to our emotional attachment to dogs, capitalize on our desire for expert approval, or that exploit our fascination with the lives of celebrities.

Appeal to Emotion 3    Appeal to Authority 1

                    APPEAL TO EMOTIONS                                             APPEAL TO AUTHORITY

 

Appeal to Celebrity

APPEAL TO CELEBRITY

One of my personal favorites of the “I love celebrities” category is an ingenious brand of Nestle’-Purina’s in which the celebrity to whom the product refers, supposedly a famous chef, does not, um, actually exist…….

Chef Michael

The Ad: It’s not just dog food. It’s Chef Michael’s. Crafted with great care, attention to detail and inspiration from our executive chef”

The Disclaimer: In the spirit of full disclosure (and to avoid litigation), the company provides the following response to inquiries about the whereabouts of the personage who is Chef Michael: “Chef Michael is not a real person, but a reflection of the many people inspired to make mealtime special for their dogs”.  I dunno. I think I would still like to get the guy’s autograph.

So, pick your poison – there is a dog food advertising campaign out there designed to appeal to just about every dog owner demographic. And, even though each and every one of us will insist that these schemes do not work on us (and that we select a dog food based solely upon its nutrient content, ingredient quality and suitability for our dog, thank you very much), these campaigns do indeed work very well.

Marketing’s Holy Grail: One category of advertising claims that has been shown to work particularly well, increasing human and pet food sales more than any other, are health claims. Because of the cumulative effects of a series of three laws that were passed in the 1990’s, the regulatory oversight of health claims on foods has been drastically curtailed over the last 35 years. Over time, the loss of regulatory oversight over health claims in human foods has led to labels that look like this:

Health Claims Human Foods

Dog foods quickly followed suit.  And pet foods are no different. As it stands today, pet food companies may include general health claims on their labels with no legal obligation to substantiate those claims. In other words, they neither have to prove the claim nor provide any evidence supporting the claim to any regulatory agency. Marketers must simply word their brand name or advertisement carefully enough to prevent the FDA from considering it a drug claim (which are regulated).

The difference between a general health claim (allowed and no proof needed) and a drug claim (not allowed; regulated by FDA) for pet foods turns on just a few words and phrases, as shown in the table below from Dog Food Logic.

Claims Table

TABLE EXCERPTED FROM “DOG FOOD LOGIC“, by Linda P. Case, page 175

Here are a few product examples:

Skin Coat 3                 Skin Coat 5            Skin Coat 7                        Skin Coat 8

Might these health claims be confusing to pet owners? A recent study asked exactly that question. 

The Study: A group of researchers at Tufts University’s Cummings School of Veterinary Medicine examined the nutrient profiles and ingredients list of 24 brands of dog food that all were marketed for skin and coat health (1). The objective of their study was to identify consistencies (or inconsistencies) among different commercial products making claims of promoting skin and coat health in dogs.

Results: They examined 15 dry (extruded) foods and 9 canned foods, representing 11 different brand names. Here are their results:

  • Its all in the name: All 24 products included the terms skin, coat plus a descriptor of skin/coat health in their brand name. They also included additional health-related terms on their labels and on websites. The most commonly used were sensitive, skin sensitivities, digestive sensitivity, digestive health, and limited/unique ingredients.
  • Ingredients: If you had thought there would be a handful of specific ingredients that are known to be beneficial to skin and coat, think again. The protein sources in the 24 foods were all over the map and included chicken, fish, egg, venison, beef, pork, duck, lamb, soy, peas, and turkey. A similar cornucopia was found for carbohydrate sources, with rice, potato, wheat, oats,  barley,  millet, corn, quinoa and tapioca all making an appearance.
  • Not so special fatty acids: Thirteen of the 24 foods (54 %) identified fatty acids as nutrients that are important for skin and coat health. While this may be true for certain specific omega-6 and omega-3 fatty acids (and their ratios), 10 of the 13 foods did not identify these by name but instead used vague (and meaningless) terms such as “omega fatty acids” or “omega oils”. Less than a third of the foods provided information about the amount of any specific fatty acid in the food. When this information was provided, the range in EPA and DHA (two important omega-3 fatty acids) concentrations overlapped with those found in foods not labeled for skin/coat health.
  • More nothin’ special: The essential nutrient content and caloric density (number of calories per cup) of the 24 foods varied enormously and overlapped with other brands that are sold for adult dogs but which are not specifically marketed for skin health. (In other words, not to put too fine a point on it, there was nothing that was consistently special or unique about the nutrient content of these foods. Even omega-3 fatty acid concentrations were all over the map, making the claims of “Source of Omega-3 Fatty Acids” essentially useless to consumers).

Conclusions: The researchers were rather circumspect in their conclusions, stating that the wide variety of ingredients and large range in nutritional value of products marketed for skin and coat health make product selection for owners who are interested in these foods confusing. (Personally, I go further than “confusing”).

 

soapbox

OUT COMES THE OL’ BOX….

Up on My Soapbox: I could be wrong, but I rather doubt that a concerned owner, whose dog is experiencing skin or coat problems and who sees a food that is specifically labeled “Sensitive Skin“, stops and ponders: “Well, the company does not actually state outright that this food cures sensitive skin problems. Nor do they say that they have proven that the food supports healthy skin. Therefore, I know better than to expect this food to do much of anything at all to help my dog”.

I may be going out on a limb here, but I believe this owner is much more likely to be thinking “Oh, look! A food that is designed to help Muffin’s sensitive and itchy skin! I will give it a try because poor Muffin’s skin has been terribly bad lately. I bet this food can help her!”. Ka-ching. Another day, another unregulated and misleading pet food claim, another sale. Poor Muffin.

Take Away for Dog Folks: If your dog is continually or excessively itchy or has skin problems, please make a visit to your veterinarian, not to your local pet supply store. It is important to obtain an accurate diagnosis for skin problems because the majority of these are not related to food. Rather, the most common causes of excessively itchiness in dogs are allergies to environmental allergens such as house dust mites, pollens and molds or fleas. Only after these causes have been eliminated should food be looked at as a potential underlying cause. (Note – The diagnosis of food allergy can only be made through the use of an 8 to 10 week elimination feeding trial, which is a topic for another blog at another time).

(By the way, if you find Chef Michael, get an autograph for me).

Cited Reference: Johnson LN, Heintze CR, Linder DE, Freeman LM. Evaluation of marketing claims, ingredients, and nutrient profiles of over-the-counter diets marketed for skin and coat health of dogs. Journal of the American Veterinary Medical Association 2015; 246:1334-1338.

 

 

 

Dogs are Carnivores, Right?

There is a great deal of confusion (and opinion) today regarding how to classify the domestic dog. Those who identify dogs as carnivores (meat-eating) animals tend to focus on the predatory nature of the dog’s closest cousin, the wolf. Conversely, those who are inclined to classify the dog as an omnivore (consumes both plants and meat) rely upon the dog’s scavenging nature and ability to consume and digest a wide variety of food types. So, which is it? And, perhaps more importantly why does what we call the dog, carnivore or omnivore, seem to matter so much to us? (And why do discussions about this issue seem to quickly escalate into shrillness, name-calling and spamming?)

That Escalated Quickly

First, let’s all just calm down. From a scientific viewpoint, it appears that some confusion may arise from the dual use of the term “carnivore”. This term is used as both a taxonomic classification and as a description of a species’ feeding behavior and nutrient needs. Both dogs and cats are classified within the taxonomic order of “Carnivora”, a diverse group of mammals that includes over 280 different species.

Taxonomy

Some eat meat…..some don’t: While many of the species within Carnivora hunt and consume meat, not all are predatory or nutritionally carnivorous. The species within the order Carnivora vary considerably in the degree of dependency that they have upon a meat-based diet. For example, all of the cat species, including our domestic cat, Felis catus, are obligate carnivores. In contrast, bears and raccoons consume both plant and animal foods, while the Giant Panda subsists on a vegetarian diet. Therefore, while all of the species within the order called Carnivora can eat meat, their typical feeding behaviors exist along a broader spectrum, ranging from the obligate carnivores at one end to animals that are almost completely herbivorous at the other end.

So, where does the dog fall along this spectrum?

Cats vs Dogs: Let’s consider this question by comparing our two best animal friends, the dog and the cat. The label “obligate carnivore” (sometimes called true carnivore) means that the cat is incapable of surviving on a vegetarian diet and must have at least some meat (animal tissue) in its diet. This means that a diet that is composed of all plant materials cannot meet all of the cat’s essential nutrient needs. Specific nutrients that are problematic if Fluffy is fed a vegetarian diet include Vitamin A, a type of amino acid called taurine, and an essential fatty acid called arachidonic acid. All three of these nutrients are found in a form that cats can use in meat products and but are not found in plant foods. During evolution, cats either lost or never developed the ability to produce these nutrients in the body from the precursor forms that are found in plant foods.

The Adaptable Canine: In contrast, most of the canid species, including the domestic dog, are more generalist in their eating habits and subsequently in their nutrient needs. In the wild, wolves and coyotes exist as opportunistic predators, hunting and eating the type of prey that happens to be available. In addition to the flesh of their prey, wild canids readily consume viscera (stomach, intestines) which contain partially digested plant matter. Canid species also scavenge carrion and garbage and regularly consume fruits, berries, mushrooms, and a variety of other plant materials. Similar to its wild cousins, the domestic dog is a predatory species that also consumes plant foods and scavenges, and is capable of consuming and obtaining nutrition from a wide variety of food types.

Not only does the dog naturally choose a wider variety of foods to eat than do cats; the dog is capable of deriving needed nutrients from plant foods more efficiently than do cats. Let’s look at the three nutrients that we mentioned earlier; Vitamin A, taurine and arachidonic acid:Dogs vs cats

Finally, anatomically, dogs’ gastrointestinal tracts, from their mouths to their intestines, are consistent with other predatory species (i.e. meat-eating) that consume a varied diet. They have some ability to grind food (molars), and possess a small intestine that is longer in length (relative to body size) than that of obligate carnivores, but that is shorter in length than that of herbivorous species.

Altogether, the nutrient, metabolic, and anatomical characteristics of dogs place them on the omnivorous side of the spectrum within the wide range of species who hunt prey, scavenge, and consume plant foods

Carnivore Evidence

When we look at the evidence, we see that both nutritionally and taxonomically, the dog is best classified as an omnivore, an animal that consumes and derives nutrition from both animal and plant food sources. More specifically, the dog evolved from a species that made its living primarily through hunting and consuming prey but that also consumed whatever was available through scavenging. (Anyone who lives with a Golden Retriever is well acquainted with the scavenging part).

Time to drag out the box.

soapbox

UP ON MY BOX

So, why is it that we read multiple websites, listen to certain “experts”  and talk to Joe next door (who happens to know a lot about dogs) and they insist that the dog is an (obligate) carnivore? Why are some folks so incredibly (and one might venture, obsessively) invested in this belief? Not to put too fine a point on it, many proponents of the “dog as carnivore” hold on to this conviction like a dog with a meaty bone. One may wonder, why is this distinction even important, except perhaps for academic interest?

My own opinion is that the keen interest that we see in recent years is caused by an unusual and somewhat unprecedented focus on a desire to “feed dogs naturally.” Oddly enough, prior to the development of commercially prepared dog foods in the early 1900’s, domestic dogs were fed naturally – they were fed scraps of human food…..in other words, they scavenged. So, we appear to have come full circle, with the only difference being that the fervent adherence to a mantra of “feeding dogs naturally” now focuses on the dog’s hunting and meat-eating history rather than on its equally significant existence as a proficient scavenger.

dog at table

I’D LIKE SOME OF WHAT YOU ARE HAVING, PLEASE.

Do dogs thrive on diets that include animal-based ingredients (i.e. meat, poultry, fish) – Yes, definitely (and especially if those ingredients are of high quality). Do dogs enjoy (and probably prefer) meat in their diets. Probably. Do dogs have a nutritional requirement for animal-based ingredients in their diets? No, they do not.

EXCERPTED FROM: Dog Food Logic: Making Smart Decisions for Your Dog in an Age of Too Many Choices, by Linda P. Case (click below for purchasing in formation).

dog-food-logic-cover-final

Got Gullet?

Innovative dog chews and treats are all the rage these days. Despite the claims of their sellers, most of these products are new twists on an old theme – taking the parts of food animals that we typically discard as inedible waste and turning them into expensive and often highly sought after dog treats. A few examples are bully sticks, pig ears, pig/cow hooves, cod skins, and the topic of this essay, beef gullets (esophagus) and tracheae. In addition to coming in a dried form as a chew, the entire neck regions of beef, lamb, chicken, turkey and other food animals are also included in some commercial and homemade raw diets.

The Question Is: Are gullets and tracheae (necks) safe for dogs to consume?

Beef Gullet Twist  Beef Gullet Chew  Beef Gullet

The Answer: Not if the thyroid gland came along for the ride.

Thyroid Gland 2

Quick Anatomy Lesson: The thyroid gland is a small organ that wraps around the upper portion of an animal’s trachea (wind pipe). When a cow is dissected for the production of human-grade meat, the trachea and esophagus are removed together as by-products. Although a law passed in 1986 prohibits their inclusion in human foods, these animal parts can be used in pet foods, which is exactly where they end up (along with other animal by-products that are deemed not for human consumption).

Thyroid Tissue in Your Dog’s Food: Thyroid tissue contains the hormone thyroxine, which will not be destroyed by the dog’s gastric acid or digestive enzymes. It is absorbed into the body and remains active. If a dog consumes enough thyroxine from the diet, an elevation in circulating thyroid hormone occurs and the dog develops hyperthyroidism (or more technically correct, thyroidtoxicosis). Some dogs develop elevated serum thyroxine but do not show clinical signs. Others develop signs that include weight loss, hyperactivity, excessive panting, and polydipsia/polyuria (increased drinking/urinating).

So, is this a problem that owners should be concerned with? Possibly; especially if you are feeding a raw diet.  Here is the evidence:

science-header

  • Twelve dogs fed raw diets: In 2012, German veterinarians at  Justus Liebig University reported elevated plasma thyroxine levels in dogs that were being fed either a raw diet or large amounts of fresh or dried beef gullet (1). Clinical signs of hyperthyroidism were reported in half of the dogs (6/12). Following diagnosis, seven owners immediately switched to a commercial dry food and stopped feeding gullet. Veterinary rechecks 2 weeks and 2 months later revealed that plasma thyroxine concentrations had returned to normal in all dogs and clinical signs had resolved. One owner did not change her dog’s diet. Repeated thyroid hormone tests showed elevated levels one and four months following diagnosis and the dog was experiencing chronic weight loss. At that point, the owner switched the dog to another food, clinical signs resolved and plasma thyroxine levels returned to normal.
  • Two more cases: Two cases were reported in 2014. In the first, an 11-month-old male Rottweiler was examined for signs of weight loss, excessive panting and increased blood thyroxine levels (2).  A complete diet history revealed that the dog was being fed a commercial raw diet. After switching the dog to a commercial dry food, signs resolved and blood thyroxine levels returned to normal. In a second case study, a two-year-old female Miniature Pinscher was examined for a failure to come into estrus (3). The dog was fed a homemade raw diet that included beef cuts from the head and neck region purchased from a local butcher shop. The dog had highly elevated serum thyroxine levels.  Changing the dog’s diet led to normalization of serum thyroxine and normal estrus cycles.
  • Raw foods and chews: Most recently, a study published in the Journal of the American Veterinary Medical Association reported findings of thyrotoxicosis in 14 dogs fed either a commercial raw diet or a variety of different chews or treats (4). All of the treats were some type of sliced or rolled jerky chew. Clinical signs resolved and thyroid hormone levels were normalized within four weeks of discontinuing the suspect products. The authors were able to obtain seven samples of the brands of food or treats that owners were feeding. When tested, all had elevated thyroxine levels when compared with control foods. The authors end with this statement: “The presence of high T4 concentrations in a variety of pet foods or treats sold under different labels suggests that the problem of thyroid tissue contamination of such items may be widespread and not confined to only a few products or manufacturers.”  (The authors also sent samples and identifying information about the products to the FDA for further investigation).

Take Away for Dog Folks: Okay, before raw feeders start flooding my blog with hate mail and sending in the trolls, let me state up front that these research results are by no means presented as a personal vendetta against feeding raw. 

No Trolls

NO TROLLS PLEASE

Those of you who have read Dog Food Logic know that my position is that there are many approaches to feeding dogs healthfully, and a well-balanced, properly selected (and sourced) raw diet can be one of those approaches.

However, the evidence strongly suggests that the recent increase in diet-induced hyperthyroidism is likely a result of the increased popularity of both raw diets and of feeding unusual types of chews such as gullets and tracheae to dogs. At the very least, this set of case studies provides sufficient evidence that diet-induced hyperthyroidism is a health risk that warrants further study and investigation of the identified companies and brands.

soapbox

UP ON MY SOAPBOX

Draggin’ out the ol’ box: Fear not. I do have a personal opinion on this matter (though I would be hesitant to go so far [yet] as to call it a vendetta). This has to do with data reported in the 2015 study, which were collected in the United States. In that study, all 14 of the dogs were being fed commercially prepared foods at the time of diagnosis. These were foods that the owners purchased from a company, trusting that the products would not only provide good nutrition to their dogs, but that they were SAFE. This should not be such a high bar to clear, yet it repeatedly seems to be for the pet food industry.

Here’s the thing: The knowledge that the presence of animal thyroid tissue in foods can cause hyperthyroidism is not new information. Outbreaks of diet-induced hyperthyroidism in people are well-documented and are the reason that “gullet trimming” as a source of ground beef was outlawed in the 1980’s. Yet, these tissues are still allowed in the foods that we feed to our companion animals. Why is this?

I maintain that pet owners should be able to easily discover exactly what is in the pet foods they feed to their dogs, including the source and quality of the product’s protein ingredients.  Yet this information is rarely provided and requests are often ignored, denied or responded to with evasive platitudes and assurances. Here’s a suggestion – Ask your pet food manufacturer if the food that you feed contains animal necks and if they guarantee that it does not contain thyroid tissue. Let me know what you hear back.

Request Denied

In a perfect world (and when I am queen), we will ban the inclusion of unsafe body parts in the foods that we feed to our canine family members. I know it is an outrageous suggestion, but a person can dream, cant’ she?

Got Gullet? Let’s hope not.

Cited References:

  1. Kohler B, Stengel C, Neiger R. Dietary hyperthyroidism in dogs. Journal of Small Animal Practice 2012; 523:182-184.
  2. Cornelissen S, De Roover K, Paepe D, Hesta M, Van der Meulen E, Daminet S. Dietary hyperthyroidism in a Rottweiler. Vlaams Diergeneeskundig Tijdschrift 2014; 83:306-311.
  3. Sontas BH, Schwendenwein I, Schafer-Somi S. Primary anestrus due to dietary hyperthyroidism in a Miniature Pinscher bitch. Canadian Veterinary Journal 2014; 55:781-785.
  4. Broome MR, Peterson ME, Kemppainen RJ, Parker VJ, Richter KP. Exogenous thyrotoxicosis in dogs attributable to consumption of all-meat commercial dog food or treats containing excessive thyroid hormone: 14 cases (2008-2013). Journal of the American Animal Hospital Association 2015; 246:105-111.

Excerpted from: “Only Have Eyes for Your: Exploring Canine Research with the Science Dog” (2016).

coversnip

 

 

What’s the Deal with Meals?

 

 

nestle-purina logo            Versus 2              Blue Buffalo Logo

The Pet Food Wars: In May 2014, Nestlé-Purina, the largest producer of pet foods sold in the U.S., filed a lawsuit against Blue Buffalo, a competitor. Among other things, the lawsuit alleged that Blue Buffalo’s marketing claims—that their foods contained no by-product meals—were false and disparaging to other companies’ products. According to the report of a testing laboratory hired by Nestlé-Purina, at least a few varieties of Blue Buffalo dry extruded foods (kibble) did indeed contain poultry by-product meal, comprising as much as 25 percent of the meal in some of its products. As is the way of the modern pet food industry, within days, Blue Buffalo responded with a countersuit of its own, accusing Nestlé-Purina of defamation, unfair competition and false advertising.

Central to this public (dog) food fight was the belief, strongly promoted by Blue Buffalo, that chicken or poultry meals are of superior nutritional value to by-product meals, and that high-quality dog foods contain the former and reject the latter. (It is of interest to note that Nestlé-Purina sidestepped the nutrient quality issue altogether in their lawsuit. Rather, they contended that Blue Buffalo had falsely promoted itself as being completely transparent to its customers.)

keep-calm-and-deny-deny-deny-4

Deny, Deny, Deny: Initially, Blue Buffalo responded to the allegations with denial. Both companies launched public-relations campaigns that included strongly worded letters to consumers. However, in October, Blue Buffalo had to eat crow (meal?) when they announced that one of their suppliers, Texas-based Wilbur-Ellis, had mislabeled an ingredient, which resulted in the presence of poultry by-product meal in some of their foods. In the words of Blue Buffalo’s founder, Bill Bishop: “So, while their customers were ordering and paying for 100 percent chicken meal, at times they were receiving shipments that contained poultry by-product meal. As a result, we have stopped doing business with this plant.

What is the truth? Are by-product meals lower in quality when compared with meals? Should discerning dog owners avoid chicken or poultry by-product meal and choose only foods that contain chicken or poultry meal? And is this a reliable way to distinguish between high-quality dog foods and foods of lesser quality?

Perhaps the best place to start is with an understanding of what a “meal” actually s.

Meals – The Protein Ingredient: Every ingredient that goes into a dog food contains a unique set of essential nutrients that it contributes to the finished food. In commercially prepared dry (extruded) dog foods, various types of meals are used to provide protein. These are classified in several ways.

  1. Plant vs. Animal Source: Examples of commonly used plant-based protein meals are corn gluten meal, soybean meal and pea protein (or meal). In general, plant-based protein sources are an inexpensive source of protein and are found in foods marketed to pet owners interested in economy. The quality of these meals is moderate to low in terms of amino acid balance and digestibility, although several protein sources are used to ensure that all essential amino acid needs are met. Animal-source protein meals, on the other hand, vary tremendously in both source—animal species—and in quality measures such as digestibility, amino acid content and amino acid availability.
  2. Species vs Generic Group: Animal source protein meals may be provided as species-specific meals or as generic animal groups. Examples of species-specific meals are chicken, bison, beef, salmon, venison, turkey and lamb meals. Alternatively, these meals may be classified more largely as poultry (contains varying amounts of chicken, turkey or duck), fish (contains multiple fish species), or meat (contains varying amounts of pork, beef or sheep). When you see a named species as the major protein meal ingredient, it generally indicates that the food is of higher quality (or at least a better-regulated product). Ingredient supply companies are required to keep these ingredient streams separate and designated, which means that sources are not mixed and translates to a more uniform product and greater regulatory oversight. Conversely, the generic term used to describe a group of food animals means that the meal may contain a mixture of species with no guarantee of any particular animal species or proportions in a given product. At the production level, this also means that several ingredient streams are combined, with varying sources of origin, regulatory oversight and quality attributes.
  3. Meals vs. By-Product Meals: The term “by-product” is the designator receiving the most attention. It is important to know that on pet food labels, this term is only applied to chicken and poultry meal. And, the distinction is largely bureaucratic; the Association of American Feed Control Officials (AAFCO) sets the definitions for ingredient terms and they have not designated a by-product meal term for any other animal protein meal. The closest they’ve come is “meat” meals versus “meat and bone” meals; the latter contains bone, which can reduce its quality as a protein source. (More about the purported differences between chicken/poultry meal and by-product meal later).

Meals are Produced via Rendering: Rendering is a cooking process that converts slaughterhouse products that have been deemed unfit for human consumption into a form that is regulated as acceptable for use in pet foods. Generally, animal parts used for rendering are those not typically consumed in our Western diet: organ meats such as spleen, kidneys, liver; stomach and intestines; varying amounts of bone; and, in the case of poultry, necks, feet and heads. In addition to slaughterhouse waste, “spent” layer hens from the egg industry and food animals found to be too diseased or injured to pass inspection for use as human foods may also end up at the rendering plant. Classified during the slaughter process as “inedible,” these parts are redirected into an alternate supply stream and are handled, transported and processed differently than those intended for human consumption.

The Process: During the rendering process, the combined components are ground, mixed and heated to a high temperature (220° to 270° F), which cooks and sterilizes the mixture, effectively killing the microbes that are present. Sterilization is absolutely necessary because refrigeration is not required for the handling or transport of inedible foods. The resulting slurry is centrifuged at high-speed to remove lipids (fat). The removed fat is further processed and eventually is sold separately as chicken, poultry, or animal fat. The mixture that remains is dried and ground to a uniform particle size that ultimately has the appearance and texture of dry corn meal. Animal protein meals are very low in moisture and contain between 55 and 65 percent protein, making them a rich source of protein when included in a pet food.

Chicken Meal

THE END RESULT – CHICKEN MEAL

Why use Protein Meals? From a commercial perspective, meals are well suited for use in dry foods because they can be stored and transported easily, and have the low moisture content necessary for extrusion processing. By comparison, high-moisture protein ingredients, such as “fresh” chicken (or other meat), contribute only small amounts of protein by weight to the end product because the water is cooked off during the extrusion process. These ingredients may be listed first on a food’s ingredient list simply because they contain more than 65 percent water, and ingredients must be listed in predominance by weight at the time of processing. In reality, it is the dried meals, usually found within the first three to five ingredients on the list, that provide the bulk of dietary protein in dry dog foods.

It Aint’ your Grandma’s Roast Chicken: According to AAFCO, the term “meal” refers to the “dry, rendered product from a combination of clean flesh and skin with or without accompanying bone, derived from the parts of whole carcasses of [chicken/poultry], exclusive of feathers, heads, feet and entrails.” (1)  Although this definition seems to suggest that meals are produced from the same parts of the chicken that make it to the supermarket for human consumption, this is simply not true. As mentioned previously, animal protein meals are produced from slaughterhouse waste and other food animals that are deemed “not for human consumption” (i.e., inedible).

In the case of chicken, these waste products are predominantly “chicken frames,” the remainder of the chicken’s body after the parts destined for human consumption have been removed. More than 70 percent of a broiler chicken ends up in the supermarket, leaving about 30 percent in the frame, which is made up of a bit of muscle meat plus a lot of connective tissue and bone.

Chicken Frames

CHICKEN FRAMES

None of the animal protein meals that are used in the production of dry dog foods are produced from edible (human grade) meats. This is because rendering plants are in the business of taking inedible animal parts and converting them into a form that can be fed to non-human animals. Chicken meal comes from chicken frames that are designated as not for human consumption, not from supermarket chicken.

        Chicken Meal          Unequal Sign       Fresh Chicken             

The Deal (with By-Product Meal): By-product meals are composed of exactly the same chicken components found in meals, but by-product meals may also contain varying quantities of heads, feet and viscera (guts). Therefore, the difference between a chicken (or poultry) meal and its respective by-product meal is the inclusion of heads and necks, feet, and guts (viscera) in the latter and the exclusion of those body parts from the former. On the face of it, this appears to be an obvious quality distinction. After all, any product that has heads, feet and guts in it not only sounds yucky, but certainly must also be of poor quality, right?

Well … it depends.

Given this definition, the general (and understandable) perception is that meals will be of higher quality than by-product meals. This is clearly the conclusion that Blue Buffalo and other pet food companies that make “No By-Products!” claims on their labels are banking on. However, consistent and substantial quality differences between the two ingredient types are not reported. The fact is that the inclusion of additional body parts (heads, feet and guts) in by-product meals can reduce, maintain or improve the quality of a meal (2).

Beaks, Feets and Guts, Oh My! These three additional parts, although certainly not very appetizing to most people, have varying nutritional value as food ingredients. First, the protein quality of viscera (internal organs and intestinal contents) is similar to that of chicken flesh components included in very high-quality chicken meals (and to what humans consume in a chicken dinner). In other words, including organ meats and intestinal contents in a by-product meal does not negatively affect the meal’s protein quality and may even improve it in a poor or average quality meal. Second, the inclusion of chicken heads in the mix results in a slight reduction in nutritional quality. This is because chicken brains are highly digestible while chicken skulls, being comprised of bone, are less so. So it appears to be a zero sum game when it comes to the added chicken heads. Last – chicken feet. As a food ingredient that is intended to provide dietary protein, feet are simply bad and have measured quality values similar to feeding connective tissue or bone residue.

Feet Less than symbol Heads  Less than symbol Chicken Guts

       FEET (BAD)                                        HEADS (LESS BAD)                           GUTS (BETTER)

Collectively speaking, including additional body parts in a by-product meal may affect the resultant product’s protein quality either positively or negatively when compared with its corresponding meal. The influence depends largely upon the actual proportion of the three different body parts that are included in the end product: if there are lots of guts, quality improves. Heads: could go either way. Feet: bad news.

And, by the way, specifics on the type and quantity of these additions is information that consumers are never privy to.

So, Why All the Hype? Studies of the digestibility and protein quality of meals and by-product meals have found that as a group, meals are slightly more digestible and contain slightly more available essential amino acids than their associated by-product meals (3,4). However, there is also a lot of overlap between the two ingredient groups, meaning that a given meal may be better, equal to or even lower in quality than a given by-product meal.

Overall, the differences that have been found are neither dramatic nor worthy of the hysteria that seems to accompany the word “by-product” among dog owners and some pet food companies. Therefore, the marketing hyperbole and excessive “patting oneself on the back” by companies that include meals but not by-product meals should be viewed by all dog owners with a hefty dose of skepticism. True, there is some difference, but probably not enough of a quality difference to warrant the inflammatory language and excessive claims that are being made by companies jumping on the by-product-free bandwagon.

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Draggin’ Out the Ol’ Box Again: I would suggest that this exaggeration of difference has occurred (and been actively promoted) because there are so few available ways for dog owners to accurately assess the quality of ingredients, especially protein ingredients, in commercial pet foods. As a result, this single AAFCO-defined difference (meals vs. by-product meals) has caught on like a house on fire, with marketing campaigns flinging additional gasoline to fuel the flames and causing this distinction-without-a-difference to garner more importance than it comes even close to warranting.

It is an unfortunate paradox that one of the most important nutrients for dogs (protein) is supplied by a type of ingredient (protein meals) that consumers have almost no way of evaluating. This is especially concerning given that animal-source meals can vary tremendously in the components that make them up and ultimately in their quality (i.e. in nutrient content and digestibility). The three designators discussed previously —plant- vs. animal-source, species vs. generic and meal vs. by-product meal — are the only protein-ingredient quality designators available to consumers. This might not be an issue if they were in truth the most important quality differences among animal protein meals. However, they are not. Animal protein meals differ in ways that are invisible to consumers and can significantly influence the quality of the foods in which they are used:

  • Bone and connective tissue: Animal-source protein meals contain varying amounts of bone and connective tissues (this pertains to both meals and by-product meals), which affects the product’s protein quality and mineral balance. Bone matrix and connective tissues contain the protein collagen, which is poorly digested and utilized when included as a dietary protein source, and bone contributes excess amounts of calcium and several other minerals. Meals that are high in collagen and minerals from bone and connective tissues are of lower quality than those that contain a larger proportion of muscle meat.
  • Transport and contamination: Because inedible food products are not refrigerated or subject to the same handling regulations as foods destined for human consumption, both the handling and transportation of raw materials can affect the quality of the end product. If rendering is conducted at the slaughterhouse of origin, the meal is usually produced within a day or two following slaughter. However, when raw materials are transported to a rendering plant in another location, the time spent during transport under unrefrigerated conditions can lead to increased microbial contamination and oxidative damage.
  • Processing: Differences among rendering plants also exist and are important for the end product. High temperatures or excessively long cooking can damage a meal’s protein, making certain essential amino acids less digestible and available.
  • Supplier integrity: Finally, as seen with the Blue Buffalo case, pet food companies are at least somewhat dependent upon the integrity and honesty of their ingredient suppliers. A division within the animal feed industry designates some meals as pet-food grade and others as feed grade, with the former containing a lower percentage of ash (minerals) (5). In addition, some pet food companies select only meals that meet a particular standard, while others impose additional refining methods on their protein meals to increase digestibility and improve protein quality.
  • Tests that we do not hear about: Various analytical tests are used to measure a meal’s digestibility and amino acid availability, and many pet food companies also routinely measure the digestibility of their foods using feeding trials. However, this information is not easily available to consumers, and pet food companies are under no obligation to accept or reject meals of different quality levels or to share such information with consumers.

To date, there is no way for pet owners to differentiate among dry (extruded) dog foods that use high-quality animal protein meals and those that use poor-quality meals, other than the cost of the food and the three designators discussed previously. You can contact the company and specifically ask for information about the food’s protein digestibility and quality, of course. However, you may be disappointed. While researching my book Dog Food Logic, I contacted the manufacturers of more than 30 different pet-food brands and requested protein and diet digestibility information for each of the products. I received no reply at all from the majority of companies and useful information for just two of the brands.

 Are There Any Other Options? In today’s innovative market place, there are indeed a few. Two other animal-source protein ingredients (in addition to fresh meats prepared at home) are those that are either freeze-dried or dehydrated. Freeze-dried ingredients are typically used in raw food diets, but can also be cooked prior to packaging. Dehydration usually uses heat treatment to kill microbial growth and so moderately cooks the meat. These sources are likely to be of higher quality and digestibility because they have not undergone the high heat processing that meals are subjected to.

Dehydrated chicken                           Freeze dried chicken                 DEHYDRATED CHICKEN                                        FREEZE-DRIED CHICKEN 

If they are human-grade meats, all the better, as this means that the ingredients and the end-products were handled and produced using the same regulatory oversight as required with human foods. However, with a few exceptions, neither freeze-dried nor dehydrated meat sources are routinely used as the primary protein source in dry, extruded foods. Nor have I found a source of dried protein meals produced using human grade (i.e., edible) meat sources and human food processing methods. To do so (and to promote them as such) would add a dimension of choice and distinction regarding the quality of dry dog food that does not exist today. Dry extruded dog food continues to be the most popular type of dog food sold in the U.S., and I believe such products would be welcomed by owners willing to pay a bit more for a better regulated and higher quality food.

Take Away for Dog Folks: While rendered animal meals can be of high quality and can provide an excellent protein source in dry dog foods, if the animal-source meal has been poorly sourced, handled, processed, or regulated, its protein can be damaged, making it a poor source of essential amino acids for dogs and reducing the digestibility and quality of the entire diet. Unfortunately, there is no way for consumers to tell from a food’s label if the meal used is of high, moderate or low quality. Because meals make up the bulk of protein in dry dog foods, information about their quality, and by extension, how nourishing they are, is the most important consideration that we should be concerned with when we look at an ingredient list.

The problem is, despite what companies beating the “No By-Products” drum would like us to believe, we have no way of knowing which animal protein meals are better than others.

Cited References

  1.  Association of American Feed Control Officials. 2010. Official Feed Definitions; pp. 326–322.
  2. Aldrich, Daristotle. 1988. Petfood and the economic impact. Proceedings of the California Animal Nutrition Conference, Fresno, CA; pp. 1140–1148.
  3. Cramer, Greenwood, Moritz. 2007. Protein quality of various raw and rendered by-products commonly incorporated into companion animal diets. Journal of Animal Science 85:3285–3293.
  4. Locatelli, Howhler. 2003. Poultry byproduct meal: Consider protein quality and variability. Feed Management 54:6–10.
  5. Dozier, Dale, Dove. 2003. Nutrient composition of feed-grade and pet-food-grade poultry by-product meal. Journal of Applied Poultry Research 12:526–530.

Excerpted from: “Only Have Eyes for Your: Exploring Canine Research with the Science Dog” (2016).

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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 product 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).

Excerpted from: “Only Have Eyes for Your: Exploring Canine Research with the Science Dog” (2016).

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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.

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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.

Excerpted from: “Only Have Eyes for Your: Exploring Canine Research with the Science Dog” (2016).

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