Digestibility Matters

In  “Dog Food Logic” and “Only Have Eyes for You“, I have emphasized (okay, some might say “harped upon”) the need for pet food companies to provide digestibility information to consumers. It is not a difficult value to determine and most pet food companies already conduct feeding trials that measure this (yet keep the results to themselves). As one of the most basic measures of food quality, digestibility provides essential information that can help dog owners to select the best food for their dog.

What is digestibility (and why does it matter)? To refresh, digestibility reflects a food’s ability to deliver essential nutrients to the dog who is eating it. This ultimately affects not only defecation quantity and quality (how much your dog poops and how the poop looks and smells), and a dog’s propensity for flatulence (no explanation needed), but more importantly, a dog’s longterm health and wellness. This graphic, presented in the essay, “Scoopin’ for Science“, summarizes how digestibility is measured using feeding trials with dogs.

Digest Trials

In case you have not noticed, it is that last step, “Provide Results to Consumers” that is glaringly absent from the dog food scene. But, I harp (again).

Onward. There is good news to tell.

Good vs. Poor Digestibility: The term digestibility coefficient refers to the percent of a food that the dog absorbs into his or her body during the process of digestion. As a rule of thumb, dry dog foods with digestibility values of 75 % or less will be of very poor quality, those with values between 75 and 82 % are classified as moderate in quality, and foods with digestibility values that are higher than 82 % are of high quality. If you see products with 88 % or more reported digestibility, you have a rock star.  (For a more detailed explanation of dog food digestibility, see “Dog Food Logic“).

The paradox lies in the fact that while many pet food companies routinely measure the digestibility of their products, they are not required to report this information to the people who buy their foods. Most do not provide this information even when it is directly requested. Digestibility matters (a lot), but we cannot judge foods with information that we do not have.

The good news is that two research studies measuring the digestibility of dog foods formulated with different types of protein sources were recently published by a group of animal nutritionists from the Norwegian University of Life Sciences and the University of Copenhagen in Denmark (1,2). The first compared the digestibility of dog foods that used three common animal protein meals and the second compared the use of fresh chicken meat (aka “chicken first”) with poultry meal as protein sources in a dry food. Because all of the protein ingredients that the researchers examined are frequently found in commercial foods, their results may be helpful to you in your search for a quality food.

Like me, you may be surprised by what they found:

Lamb, fish, or poultry meal? In the first study, the investigators compared the protein and overall digestibility of three dry (extruded) dog foods that were formulated containing equivalent amounts of either lamb meal, fish meal or poultry meal (1). Because one of the objectives of their work was to determine if mink provide a suitable model for assessing pet food quality, they tested the foods in growing mink, adult mink and adult dogs.

Results: As a protein source, lamb meal showed significantly lower values for multiple measures of protein quality and essential amino acid content when compared with both poultry meal and fish meal. Even though all three diets were formulated to provide complete and balanced nutrition, the lamb meal diet was found to be deficient in the essential amino acid methionine, when digestibility was taken into account. Although differences between poultry and fish meals were not as dramatic, poultry meal was of lower quality than fish meal. As a protein source in dog food, fish meal had the highest values on almost all quality measures, including digestibility and essential amino acid content. When tested in adult dogs, the protein digestibility values of the three foods were 71.5, 80.2, and 87.0 for lamb meal, poultry meal and fish meal, respectively. Overall, this study suggests that, at least for the sources used in this work, the order of protein quality was lamb meal (poor), poultry meal (moderate), and fish meal (high). Additionally, although the reported level of lamb meal in the diet exceeded the minimum methionine requirement for adult dogs, the actual amount of methionine that was available to the dogs (i.e. was digested) was less than their minimum requirement for this nutrient.

lamb-meal-vs-poultry-vs-fish

LAMB MEAL IS SIGNIFICANTLY LOWER IN DIGESTIBILITY THAN POULTRY MEAL AND FISH MEAL WHEN INCLUDED IN AN EXTRUDED DRY DOG FOOD

Is fresh chicken better? The team’s second study is groundbreaking. It is the first to examine whether or not there is a demonstrated benefit to including “fresh” (frozen, actually) chicken in an extruded, dry dog food. This is important because the promotion of “fresh first” on pet food labels is frequently used as a claim for higher protein quality in the product. The researchers tested the digestibility and amino acid content of fresh, raw chicken (technically referred to as “raw mechanically separated chicken meat”) before processing (cooking) and then again after it was included in a dry dog food to replace about 25 percent of the product’s poultry meal. Because raw meat has been shown to be more digestible than dry rendered protein meals, it was hypothesized that including raw chicken in the dry food would indeed improve the foods digestibility by several percentage points. (Note: Because mink had been previously shown to be a suitable model for dogs, adult mink were used to test the diets).

Results:  As expected, when tested before processing the digestibility of raw chicken meat was significantly higher than that of rendered poultry meal (88.2 % vs. 80.9 %, respectively). However, when the raw chicken meat replaced 25 percent of the poultry meal in an extruded dry food, the digestibility of the food was not significantly improved  (81.3 vs. 80.3, respectively).  In addition, the digestibility of several essential amino acids was actually higher in the food containing only poultry meal than in the food that included the raw chicken meat.

chicken-not-better-than-poultry-meal

WHEN INCLUDED IN A DOG FOOD, FRESH (RAW) CHICKEN MEAT DOES NOT IMPROVE THE FOOD’S PROTEIN DIGESTIBILITY OR AMINO ACID AVAILABILITY COMPARED WITH POULTRY MEAL

Take Away for Dog Folks

Wow. The results of these two studies contradict several previously accepted (if never actually proven) dog food edicts. These are:

  1. Lamb meal is a high quality protein source for pet foods. Um, apparently not. The first study found that lamb meal was poorly digested (70.5 %) and provided inadequate levels of an essential amino acid, methionine after digestibility was taken into account.
  2. Named species meals are always superior to generic meals. This refers to the general rule of thumb that dog folks should always choose a food that uses chicken, turkey, salmon or lamb meals over the less specific meat, poultry or fish meals. At least regarding the animal-based protein sources used in these studies, choosing lamb over the generic poultry or fish may not get you the quality you are hoping for.
  3. Chicken first on the pet food label means higher quality (more digestible) protein: Nope again. While the digestibility of fresh chicken meat was higher than that of poultry meal when tested prior to processing, incorporating fresh chicken (as 25 percent of the protein source!) into an extruded food did not improve digestibility or lead to a higher quality product. The researchers speculated that this may have occurred because raw meat ingredients could be more susceptible to damage caused by the heating and drying processes of extrusion than are rendered protein meals. Regardless of the cause, it appears that “Chicken First’ may not be the marketing holy grail that pet food companies are promoting it to be.
soapbox

UP ON MY SOAP BOX

This is great information for dog folks to have. Many thanks to this team of researchers, among others (all notably at universities, not from pet food companies) who have been publishing scientific evidence regarding the protein quality, amino acid content, digestibility and safety of various dog food ingredients and products. We are grateful to you all and hope to see more of these types of studies. Although these do not (yet) go so far as to provide us answers to the most important question: “What is the digestibility of the  brand of food that I am feeding to my dog?” they provide needed and essential information.

I have said this many times before and will say it again:

If pet food manufacturers insist on telling us that their brands of food are expected to provide “complete and balanced nutrition” throughout our dogs’ lives, then providing a few very simple measures of the quality of those foods is not too much to ask.

The researchers of these papers agree. They finish the abstract of their first paper with this statement: “Furthermore, the study showed that to ensure nutritional adequacy of dog food and to be able to compare protein quality of dog foods, information of AA [amino acid] composition and digestibility is crucial“. [Emphasis mine].

So, pet food manufacturers……..are you listening? Time to step up and provide this information on your labels, websites, or at the very least, in response to direct inquiries.  In the meantime, I will continue to report and promote research studies that provide us with the information that we need to choose smart for our dogs.

Until next time, happy feeding and happy training!

Chip and His Cake

CHIPPY WONDERS ABOUT THE DIGESTIBILITY VALUES OF HIS CAKE

Cited Studies:

  1. Tjernsbekk MT, Tauson AH, Matthiesen Cf, Ahlostrom O. Protein and amino acid bioavailability of extruded dog food with protein meals of different quality using growing mink (Neovison vison) as a model. Journal of Animal Science 2016; 94:3796-3804.
  2. Tjernsbekk MT, TAuson AH, Kraugerus OF, Ahlstrom O. Raw, mechanically separated chicken meat and salmon protein hydrolysate as protein sources in extruded dog food: Effect on protein and amino acid digestibility. Animal Physiology and Animal Nutrition 2017 (in press).

 

Happy New Year from The Science Dog! (The 2017 Pet Blogger Challenge)

Happy New Year from The Science Dog!

To start the year off, I am participating for the first time in The Pet Blogger Challenge that is organized by the travel site, Go Pet Friendly. Many thanks to my friend Eileen Anderson for alerting me to this annual event. Below are this year’s queries and my responses. I hope you enjoy learning a bit more about The Science Dog!

  1. When did you start your blog and, for anyone who is just seeing it for first time, please provide a description of your site. Would you say your blog focuses more on sharing stories with your readers, or providing a resource for your audience? Answer: I created The Science Dog in September of 2013, shortly before the publication of my fifth book, “Dog Food Logic“. The purpose of The Science Dog is to provide up-to-date, evidence-based information to dog folks and pet professionals about dog training, behavior and nutrition. My focus is primarily on original scientific research that has been published in peer-reviewed journals. I try to find studies whose results are relevant to trainers and dog owners and then summarize these in what I hope is a “user-friendly” style. Oh, and yeah, sometimes I editorialize a bit.

    soapbox

    GETTIN’ UP ON THE OL’ BOX

  2. What was your proudest blogging moment of 2016? Answer: I published the second Science Dog book in July of 2016, entitled “Only Have Eyes for You“. Both writing and promoting it has been a lot of fun! My husband Mike designed the cover for the book (as he did for “Beware the Straw Man“), and I was especially tickled that he used a photo of four of our dogs, posed in our garden. The oldest girl, Cadie, has since passed away, so this photo is very near and dear to my heart.

    Cadie Chip Vinny Cooper May 2013

    CHIPPY, VINNY, CADIE AND COOPER

  3. Which of your blog posts was your favorite this year and why? (Please include a link.) Answer: I enjoyed writing all of the posts, especially the nutrition essays, as I had focused the first two years of the blog on topics related to behavior and training. In 2015, I started to include more essays about nutrition and feeding practices. However, my personal favorite of 2016 has to be “The Perfect Dog“, because it reviews two recent papers that provide some insight into the gap between what people think a dog should be versus who dogs actually are (and also, to some degree, places the responsibility for this exactly where it lies).       Unrealistic Expectations
  4. Year after year, one goal that we all seem to share is that we want to reach more people. What one tool did you use or action did you take this year that had the most impact on increasing traffic to your blog? Answer: I use FaceBook quite a bit, and have a FB Science Dog page that gives dog folks access to the blog and allows readers to chat and to contact me directly. I love to hear from readers, especially when they have ideas for new science-based topics for the blog! (hint-hint).
  5. Which of your blog posts got the most traffic this year? (Please include a link.) Have you noticed any themes across your most popular posts? Answer: The essay that received the largest number of hits (~ 18,000) was “When Sit Doesn’t Mean S*it“. Catchy  little title aside, I think that it resonated with shelter professionals because it presents a set of research studies conducted by Alexandra Protopopova’s team that both challenged a prevailing belief about training and adoption rates and presented some unique solutions that may be more effective as predictors of dogs’ chances for adoption.   Sit Ubu
  6. What blog do you find most inspirational and how has it influenced your blog? (Please include a link.) Answer: There are a number of dog-related blogs that I follow regularly and enjoy. Two that are among the best are Eileen Anderson’s not-to-be-missed essays about dog training at EileenandDogs and Julie Hecht’s excellent research summaries at Dog Spies.
  7. What is one thing your readers don’t know about you or your pets that would surprise them? Answer: What my readers may not know (but all of my friends do) is that while I hold a Masters Degree in Canine/Feline Nutrition, I cannot cook a human food meal to save my life. I started volunteering two years ago at our local soup kitchen, The Daily Bread, and the other volunteers quickly learned this little secret. I am now a designated dish-washer and happily report that I excel at that particular task, keeping everyone safe (and well fed).

    daily-bread-people-2

    SUPPORT YOUR LOCAL SOUP KITCHEN! 

  8. What is something you’ve learned this year that could help other bloggers? Answer: Not to point any political fingers (interpret this as you like), but my advice to other writers (and citizens) is: Don’t lie and stick to the facts that have evidence to support them.    just-the-facts-maam-2
  9. What would you like to accomplish on your blog in 2017? Answer: The biggest challenge that I may have in 2017 is finding enough time to work on all of the writing and dog training projects that I am excited about. I am currently writing a new dog training book that presents evidence-based training and the applications that we use at our training school, AutumnGold, plus developing a few new training courses with several of AutumnGold’s instructors and writing essays for The Science Dog (many of which will appear, in some form, in the new book). Add in training and enjoying time with my own dogs, and it looks like it will be a busy and fun year!

    Cooper and Alice Standing Platforms

    PLATFORM TRAINING AT AUTUMNGOLD!

  10. Now it’s your turn! You have the attention of the pet blogging community – is there a question you’d like answered, or an aspect of your blog that you’d like input on? Answer: Thanks to GoPetFriendly for sponsoring this blog challenge and hop! This is a Blog Hop!

New Book! “Only Have Eyes for You: Exploring Canine Research with The Science Dog”

Only Have Eyes for You: Exploring Canine Research with The Science Dog” (paperback version) is now available! Click on the image below for more information and to order. (Kindle version will be available soon!)

Book description:  In her second Science Dog book, Linda Case tackles commonly held beliefs about canine nutrition, pet foods, behavior, social cognition and training. Each of the book’s 32 chapters explores a current issue that is of interest to dog owners and pet professionals and presents the scientific evidence that supports or refutes commonly held claims and beliefs. Learn about pet food ingredients and research showing that what is on the label may not always be in the food, about measures of food quality (and what consumers may not know about the foods that they buy), and about the safety and digestibility of popular dog treats and chews. Other chapters review new information regarding how dogs communicate, factors that help or inhibit a dog’s ability to learn, and the effectiveness of different types of training. Find out if dogs are capable of “knowing what someone else knows”, if they feel empathy for their friends, if they bark for no reason, and if they are capable of feeling guilt following a misdeed. Learn more about breed stereotyping, factors that influence our perceptions of dogs, and which canine characteristics most influence our attraction to particular dogs. This newest Science Dog book has something for everyone who works with and trains dogs, as well as for those who simply love dogs and enjoy learning more about our canine best friends.

                                                                             ♥♥♥♥♥♥♥♥♥♥♥♥♥♥

coversnip

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).

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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:

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  • 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).

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