The Science Dog Hits the Road!

Hello Science Dog Readers,

Just a quick note to let you know that the Science Dog (aka Linda Case) is going on the road for several upcoming speaking engagements, starting in October. If you enjoy reading The Science Dog blog and reading my books, this is a chance for us to meet in person and talk about the topics that we all love – Dogs and Science!

Here are details and links for more information:

Saturday, October 21, 2017 – Sarah Whitehead’s Clever Dog Company’s Annual Inner Circle Conference, London, England

Sunday, October 22, 2017 – Clever Dog Company Conference, Masterclass (full-day seminar):

Friday – Sunday, January 19 – 21, 2018 – Animal Events UK Puppy Conference, Birmingham, England:

Friday – Sunday, April 19 – 21, 2018, IAABC Animal Behavior Conference, Burlington (Boston), Massachusetts.

HOPE TO SEE YOU THERE!

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!

“Only Have Eyes for You: Exploring Canine Research with The Science Dog” – Kindle Edition Now Available!

The Kindle edition of Only Have Eyes for You: Exploring Canine Research with The Science Dog” is now available! Click on the image below for more information and to order.

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.

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

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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.

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

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What’s in Your (Vegetarian) Food?

Here we go again.

It appears that there may be more than what dog owners expect to find in vegetarian dog food.

Hold the Spam, Please: Before all of the  “Dogs are Carnivores (and a pox on your mother if you think differently)” devotees begin posting comments (in all caps ) that dogs should NOT be fed a vegetarian diet in the first place, let me state that this is not what this blog piece is about. So please, don’t even start. The point of this essay is not to argue (again…..) whether or not dogs have an absolute requirement for meat in their diet (here’s a hint: They don’t). Rather, today we examine new information about undeclared ingredients that may be present in dog food and the mounting evidence of regulatory violations within the pet food industry.

In this newest pair of studies, a team of veterinary nutritionists at the University of California tested vegetarian pet foods for label compliance and ingredient content.  I have written about this before, and unfortunately once again, the news isn’t good.

25-Foods-That-Seem-Vegetarian-But-Arent

Label Compliance: In the first study, the researchers collected samples of 24 dog and cat food brands that carried a label claim of “vegetarian” (1). The majority of the foods were over-the-counter products purchased at a local pet supply store. Three products were veterinary therapeutic diets. Of the group of products, 19 were formulated for dogs or for dogs and cats, and five were formulated exclusively for cats.  Product labels were examined for their compliance with the Association of American Feed Control Official (AAFCO) model regulations, which are the basis for most state mandated pet food regulations. Pet food samples were also analyzed for total protein and essential amino acid content. Results: Of the 24 foods, only eight (33 %) were in complete compliance with AAFCO label regulations. This means that 16 brands (66 %) had one or more violations. The most common infractions were the omission of feeding instructions or caloric content, improperly reported guaranteed analysis panels, and mislabeled ingredient statements. Nutrient analysis showed that all but one of the foods met AAFCO’s minimum crude protein requirements. However, six brands had deficient levels of one or more of the essential amino acids. This means that while the total amount of protein that the food contained appeared to be sufficient, essential amino acid requirements, which are more important, were not always met.

Presence of Animal-Based Ingredients: In a second study, the same group of researchers tested 14 brands of vegetarian pet foods (2). They purchased each food on two occasions to obtain samples as duplicates from different manufacturing batches. Six were dry and eight were canned products. Samples were analyzed for the presence of mammalian DNA using an accepted laboratory technique called multiplex polymerase chain reaction (PCR). Since all 24 foods were marketed as vegetarian (and in some cases, as vegan), none included animal-based components in their list of ingredients. Results: All six of the dry (extruded) foods that were tested contained DNA from beef, pork or sheep and five of the six contained DNA from multiple animal species. These results were consistent across batches for all 7 products.  Only one of the 8 canned vegetarian foods contained animal DNA (beef) and this finding was not repeated in the second sample. In this study, the researchers also tested for the DNA of dogs, cats, goats, deer, horses, rats, mice and rabbits. DNA from these species was not detected in any of the samples. Similar to earlier studies that have found the DNA of undeclared meats in dog foods, the amount of animal-based ingredients in the foods could not be quantified. The researchers could not speculate whether the labeling violations were a result of deliberate adulteration or unintentional cross-contamination of vegetarian products with meat-containing foods produced at the same facility.

soapbox

Soap Box Time: The Federal Food, Drug and Cosmetic Act requires that all pet foods sold in the United States are safe, produced under sanitary conditions, contain no harmful substances, and are truthfully labeled (emphasis mine). Perhaps I am being picky, but labeling a food as vegetarian and then not ensuring that the food indeed lacks the meat of cows, pigs and sheep, seems to qualify as not being truthful. (Some might even call it lying, I suppose). Not only are such egregious errors in violation of both FDA and AAFCO regulations, but they seriously impact the trust that dog owners have in pet food manufacturers. And rightly so.

To date, the majority of pet owners in the US continue to feed dry, extruded food. Of the dry-type vegetarian foods tested in this study, all of them, 100 % were, in fact, not vegetarian at all. This leads one to ponder about other products on the market and whether it is more the norm than the exception for dry dog foods that are sold as vegetarian to be nothing of the sort. While the authors note that this was a small number of products and so do not represent all vegetarian foods, the fact that all of the foods failed their DNA tests is alarming.

What can you do as a dog owner? Contact the manufacturer of your food and ask them how they verify the integrity of their products, specifically, the ingredients that they include in their foods. If they are not forthcoming and transparent with their response, find another producer who is. The good news is that the pressure that research studies such as these place on pet food companies and upon the industry as a whole will hopefully encourage increased transparency and improved regulatory oversight – something that we are apparently in dire need of.

Cited Studies:

  1. Kanakubo K, Fascetti AJ, Larsen JA. Assessment of protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats. Journal of the American Veterinary Medical Association 2015; 247:385-392.
  2. Kanakubo, K, Fascetti AJ, Larsen JA. Determination of mammalian deoxyribonucleic acid (DNA) in commercial vegetarian and vegan diets for dogs and cats. Animal Physiology and Animal Nutrition 2016;  doi: 10.1111/jpn.12506.

 

Want Flies with that Shake?

Fries with Shake Mod

Well, not actually you, but rather your dog.

Before food purists get up in arms over  this topic, consider that numerous human cultures have historically viewed insects as acceptable and even highly desirable food items. And today, our ever-expanding human population and the increasing need for sustainable sources of food have led to increased consideration of insects as food in almost all human cultures.

Insects for Dinner

So, it’s not much of a jump to ask – what might this mean for feeding dogs?

It’s all about the protein: Protein is the most expensive nutrient in the diet of all animals, including humans. It is expensive both in terms of the monetary cost of its production and its ecological impact upon the environment. In the spirit of sustainability (a buzzword that pet food companies and other corporations love to trot out) and with the goal of reduced production costs (i.e. making foods more cheaply), pet nutritionists at The Nutro Company recently identified a number of potential alternative protein ingredients for dog and cat foods. Bugs, being plentiful, cheap, and protein-replete are included on that list.

And protein is all about amino acids: Although we talk about a dog’s protein requirement and about a food’s protein level or quality, the actual requirement that dogs and all animals have is for the essential amino acids (the building blocks of the dietary protein) and the nitrogen that dietary protein supplies. The reason that the parlance of nutrition centers on dietary protein is simply because foods contain protein, not individual amino acids. It is during the process of digestion that a food’s protein is broken down in the small intestine into its component amino acids, which are then absorbed into the body. So, at the level of an animal’s metabolic needs, it is the amino acids that actually count. This is why one of the first steps that nutritionists take when examining a potential protein-containing ingredient is to examine its amino acid composition.

So, can insect protein supply all of the essential amino acids that dogs require? The nutritionists at Nutro and at the University of California at Davis decided to find out (1).

The Study: A wide variety of different plant, algae and insect species were identified as potential alternative (and sustainable) protein sources for pet foods. Within the group of insects, the researchers focused on the adult and larval forms of various species of flies, cockroaches, and ants.

Cockroach      Ants                    COCKROACHES                                                           ANTS        

 

           Blowfly adult         Blowfly larvae                          FLY (ADULT)                                                     FLY LARVAE

All of the bug samples were analyzed for total protein and amino acid content. (I will spare you the details regarding sample acquisition and preparation in case you are reading this during your lunch hour). Amino acid analysis included measurement of the 10 essential amino acids plus taurine, a special type of amino acid that is found primarily in animal tissues. Many readers are probably familiar with taurine as an essential dietary nutrient for cats. Because there is evidence that taurine may be needed during periods of physiological stress in some dogs, it has recently been classified as a “conditional essential amino acid” for dogs as well. Because sources of taurine are limited, it is an important essential nutrient to measure when considering new ingredients for dog and cat foods.

Results: Larval and adult forms of five different insect species were analysed. Here are their primary findings:

  • High in protein: Total protein levels in all of the insect species were quite high. When reported on a dry matter basis, concentrations ranged between from 46 % in Black Soldier Fly larvae to 96 % in cockroaches. (Cockroaches? Who knew?).
  • Bugs can do it: All but one species of insect (Black Soldier Fly larvae) were found to contain sufficient concentrations of protein, essential amino acids, and taurine to meet or exceed the NRC requirements for growth for dogs and cats. The finding for taurine was rather surprising because it has been previously assumed that rich sources of taurine included only skeletal muscle and organ meats.
  • Ants and flies are best: Two groups of insects, ants and adult flesh flies, contained the most concentrated sources of taurine. However, these initial results suggest that all three of the groups that were studied – ants, cockroaches, and flies – may be nutritionally acceptable protein sources for dog and cat diets.

Take Away for Dog Folks

Dogs and cats (like humans) require nutrients in their diet, not ingredients. Therefore, if a particular protein ingredient can supply most or all of the dog’s essential amino acids, is nutritious when fed, and is safe and palatable, then it technically meets the criteria (ick factor aside) to be considered as a potential dietary ingredient. Having passed the first test of adequate protein and amino acid content, where do insects fall on these other criteria?

  • Nutritious when fed: This refers to how digestible and bioavailable the essential nutrients of the ingredient actually are, when fed to the dog. For example, some insects and plants contain anti-nutritional factors, compounds that interfere with the ability to digest or use certain nutrients. Some of these compounds can be toxic or so potent as to cause illness, making their presence a clear “no-fly zone” for pets (pun intended).
  • Safety: Many species of bugs have ways to protect themselves from becoming someone’s meal. They produce toxins that cause illness or consume plants whose by-products are toxic to animals. They may also just taste really, really nasty. Clearly, toxic bugs are out.
  • Acceptability: Living with four dogs, one of whom is a notorious poop-eater, I would venture that the acceptability issue is as much about the human side of the equation than it is the dog side. Still, dogs must not just accept a bug-flavored food, they must relish it.
Dogs Watching Eating 2

THE BOYS WATCH MIKEY AS HE TRIES THE LARVAE-FLAVORED CHOW

Will owners accept it? Might Cockroach Recipe for Seniors or Fly Formula for Active Dogs be a hard sell? My (gut) instinct is to say yes, especially in the US. We all project our own preferences and desires onto our dogs – it is our nature to do so. This is why dog foods that depict entire roasted chickens and sirloin steaks on their front panels sell so well (however misleading such graphics may actually be).

Still, seeing that there is a booming market for dog foods containing alligator meat, brushtail (Australian Possum), and Unagi (freshwater eel), along with treats made from dried bull penises, pig hooves and cow tracheas, one must admit that the bar is already set pretty low. Will insect dog food be next up?

Cited Study: McCuster S, Buff PR, Yu Z, Fascetti AJ. Amino acid content of selected plant, algae and insect species: A search for alternative protein sources for use in pet foods. Journal of Nutritional Science 2014;3:e39;1-5.

 

 

 

 

 

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.