The Heart of the Matter

In mid-July, the U.S. Food and Drug Administration (FDA) released an alert to veterinarians and pet owners regarding reports of increased incidence of a heart disease called canine dilated cardiomyopathy (DCM). This disorder is characterized by weakening of the heart muscle, which leads to a decreased ability of the heart to pump, and if untreated, to cardiac failure. The reported cases occurred in breeds that are not considered to be genetically predisposed to this disorder.

Further, a significant number of the dogs were found to have reduced levels of circulating taurine in their blood and have responded positively to taurine supplementation. It is speculated that these cases are related to the consumption of foods that negatively affect taurine status, leading to taurine-deficiency DCM. Foods containing high levels of peas, lentils, other legume seeds, or potatoes were identified by the FDA as potential risk factors. These ingredients are found commonly in foods that are formulated and promoted as “grain-free.”

As these things go, there followed a lot of hype and a fair bit of hysteria in response. Let us avoid this type of reaction and instead look at the evidence – what do we currently know about the role of diet and taurine in the development of DCM in dogs and how is it that “grain-free” foods have been recently targeted as a possible dietary cause?

What is Taurine? The nutrient taurine is a unique type of amino acid, called a beta-amino sulfonic acid. It is not incorporated into proteins but rather is found primarily as a free amino acid in body tissues and circulating in the blood. Taurine has many functions, but two that are important for this discussion involve its role in normal heart function and its presence as a component of bile acids, which are needed for fat digestion. Most animals obtain adequate taurine to meet their needs by producing it endogenously (in the body) from two other amino acids, methionine and cysteine.

TAURINE

This means that while animals require taurine physiologically, most do not have a dietary requirement for taurine. The exception to this rule is the cat. Cats (but not dogs) always require a source of taurine in their food. If they do not have it, one of the diseases that they can develop (and possibly die from) is……you guessed it…..DCM.

Taurine-deficiency DCM is well documented in cats. We also know quite a lot about the dietary factors that contribute to this disease in that species. In contrast, dogs (usually) do not require a source of dietary taurine. However, we know that some dogs still develop taurine-deficiency DCM. Why does this happen? The history of DCM in cats can help in untangling what may be occurring in dogs.

Taurine-deficiency DCM in Cats: Looking back, I cannot avoid a sense of déjà vu. In the early 1980s veterinarians began reporting increased incidences of DCM in pet cats. By 1987, a role for dietary taurine was suspected. In a seminal study, a veterinary researcher at UC Davis reported low plasma (blood) taurine levels in 21 cats with clinical signs of DCM (1). When the cats were supplemented with taurine, all 21 completely recovered from the disease. This discovery led to a series of controlled studies that supported the existence of taurine-deficiency DCM developing in cats who were fed diets that contained sufficient concentrations of taurine.

What was going on?

It has to do with Bile Acids: Another role of taurine is the body is that it is necessary for normal bile acid function. Taurine is linked to bile acids in the liver to form bile salts. These compounds are secreted into the small intestine during digestion where they function to aid in fat digestion. Animals are very efficient at conserving the taurine that is secreted into the intestine by reabsorbing the bile salts back into the body further down the intestinal tract. This occurs through a process called “enterohepatic reutilization” and prevents a daily loss of taurine in the feces.

Herein lies the problem for cats with DCM: If anything happens during digestion that causes the degradation of the bile salt taurine or that inhibits its reabsorption into the body, more is lost in the feces. If this happens consistently, the cat will experience an increase in his or her daily need for dietary taurine. Simply put – if anything causes the cat to poop out more taurine-bile acid complexes (or their degraded by-products), the cat will be in danger of a taurine deficiency if a higher level is not provided in the diet.

This is exactly what was happening in the cats with taurine-deficiency DCM – and is possibly what we are seeing today in dogs. The difference is that we know what diet factors caused taurine deficiency in cats during the late 1980s. These factors are not yet fully understood for dogs (but we can make a few guesses).

Here is What We Know: The studies with cats found that several dietary factors influenced taurine status (2,3,4). These were the level and type of dietary protein, the amount and type of dietary fiber, and the degree of heat treatment that was used during food processing. These factors could affect taurine status in three ways:

  1. Bile Acid Binding: Certain fibers and peptides (small protein chains) in the food can bind with bile salts the small intestine and make them unavailable for reabsorption into the body. This results in an increased daily loss of taurine in the feces and a subsequent increase in daily taurine requirement to replace that loss.
  2. Increased Microbial Degradation: Thermal processing of protein (extrusion or canning) can lead to the production of Maillard products – complexes of sugars and amino acids and are poorly digested in the small intestine. The undigested complexes travel to the large intestine and provide an intestinal environment that favors increased numbers of taurine-degrading bacteria. An increase in these bacterial populations reduces the proportion of taurine that is available for reabsorption and reuse by the body.
  3. Reduced Taurine Availability: Taurine is found naturally in animal-based proteins but is not found in plant-based protein sources. Therefore, providing diets that include a sufficient level of high-quality animal proteins (that are not heat damaged) should ensure adequate taurine intake. However, protein that is of low quality or that has been excessively heat-treated will be poorly digested, reducing the availability of taurine and of its precursor amino acids, cysteine and methionine. (Note: Cats produce small amounts of taurine from these precursors, while dogs can produce all of their needs from them, if adequate levels are available).

In response to new information regarding the interaction of dietary factors and taurine status in cats (and their relationship to DCM in cats), the Association of American Feed Control Officials (AAFCO) increased the recommendations for dietary taurine in extruded and canned cat foods in the early 1990s. The current recommendations are 1000 mg taurine/kg (0.1 %) in dry (extruded) cat foods and 2000 mg taurine/kg (0.2 %) in canned cat foods.

So, What about Dogs? Unlike the cat, dogs that are fed diets containing adequate levels of protein should be capable of synthesizing enough taurine from the two amino acid precursors, cysteine and methionine, to meet their needs. Therefore, a requirement for dietary taurine has not been generally recognized in dogs.

Breed Predispositions: However, there is evidence – evidence that we have had for at least 15 years – that certain breeds of dogs, and possibly particular lines within breeds, exhibit a high prevalence of taurine-deficiency DCM. Genetically predisposed breeds include the American Cocker Spaniel, Golden Retriever, Labrador Retriever, Saint Bernard, Newfoundland and English Setter (5,6). Although the exact underlying cause is not known, it appears that some breeds have either a naturally occurring higher requirement for taurine or a metabolic abnormality that affects their taurine synthesis or utilization.

Size: A second factor that affects taurine status in dogs is size. There is evidence that a large adult size and a relatively slow metabolic rate influences the rate of taurine production in the body and may subsequently lead to a dietary taurine requirement. It is theorized that increased body size in dogs is associated with an enhanced risk for developing taurine deficiency and that this risk may be exacerbated by a breed-specific genetic predisposition. For example, when compared metabolically, Newfoundlands have a significantly lower rate of taurine synthesis than Beagles (7).

There is additional evidence that large and giant breed dogs have lower rates of taurine production compared with small dogs. Ultimately, studies suggest that certain dogs possess a genetic predisposition to taurine depletion and increased susceptibility to taurine-deficiency DCM and that this susceptibility may be related to the combined factors of breed, size and metabolic rate.

What is the Role of Diet? The recent spate of cases and media attention to taurine-deficiency DCM in dogs suggests that this is a very new problem in dogs. However, it is not new. A connection between diet and DCM in dogs was first described in a paper published in the Journal of the American Veterinary Medical Association in 2001 (8). What is new is the sudden focus on certain pet food ingredients and the target that appears to have been placed upon the backs of all “grain-free” pet food brands by some bloggers and veterinarians. Not to put too fine a point on this, but the 12 cases of taurine-deficiency DCM described in the 2001 paper were collected between 1997 and 2001, years before grain-free dog foods had arrived on the pet food scene. Rather than disparage one class or type of dog food (or pet food company), it is more important to look at specific dietary factors that may be involved in DCM in dogs.

Generally speaking, these are expected to be the same as those identified for cats, including low protein levels, poorly processed or heat-damaged proteins (leading to Maillard products), and the inclusion of a high proportion of plant-based protein sources such as peas and legumes.

Over the past 15 years, reduced taurine status in dogs has also been alternately associated with feeding lamb meal and rice diets, soybean-based diets, rice bran, beet pulp, and high fiber diets (9,10,11). As with cats, there appear to be multiple dietary (and genetic) factors involved. For example, it was theorized that the perceived (not proven) association between lamb meal and taurine status was due to low levels of available amino acids present in the lamb meal, or to excessive heat damage of the protein, or to the confounding factor of the inclusion of rice bran in many lamb meal-containing foods. To date, none of these factors have been conclusively proven or disproven. Although, the most recent study showed that three types of fiber source – rice bran, cellulose, and beet pulp – all caused reduced plasma taurine levels in dogs when included in a marginally low protein diet, with beet pulp causing the most pronounced decrease (11).

Complicated? You bet. This is why it is important to avoid making unsupported claims about certain foods and brands. Taurine-deficiency DCM has been around for a while in dogs and continues to need study before making definitive conclusions about one or more specific dietary causes.

What DO we know? We know that any dietary factor that reduces the availability of taurine precursors, binds taurine bile salts in the intestine, or causes an increase in the bacteria populations that degrade taurine can reduce a dog’s ability to synthesize taurine or will increase taurine degradation and/or loss in the feces. These changes could ultimately compromise a dog’s taurine status (especially if the dog was genetically predisposed) and affect heart health. In extreme cases, as we are seeing, this can lead to taurine-deficiency DCM (see diagram below).

FDA Report: The FDA report identified foods that contain high amounts of peas, lentils, legume seeds, or potatoes to be of potential concern. The FDA also stated that the underlying cause of DCM in the reported cases is not known and that at this time, the diet-DCM relationship is only correlative (not causative). However, this has not stopped various bloggers and even some veterinarians from targeting small pet food companies and/or grain-free brands of food, and implying that these foods, and these foods alone, are causing taurine-deficiency DCM in dogs. Their reasoning is that peas and legumes are present in high amounts in foods that are formulated and marketed as grain-free. However, the truth is that many companies and brands of food include these ingredients. More importantly, there is no clear evidence showing that a particular dog food type, brand, or even ingredient is solely responsible for taurine-deficiency DCM in dogs.

Rather, it is more reasonable and responsible to speculate that one or more of these ingredients, their interactions, or the effects of ingredient quality, heat treatment, and food processing may play a role. Furthermore, the underlying cause could be the protein, starch, or fiber fractions of these ingredients. As plant-source proteins, peas and lentils and legumes include varying amounts of starch (both digestible and resistant forms) and dietary fiber. These protein sources are also generally less nutritionally complete and less digestible than are high quality animal source proteins – additional factors that could influence a dog’s ability to both produce and use taurine. Potatoes, on the other hand, provide a digestible source of starch in an extruded food but also contain varying levels of resistant starch, which is not digested and behaves much like dietary fiber in the intestinal tract.

The Heart of the Matter: Because any or all of these dietary factors could be risk factors for taurine-deficiency DCM in dogs and because peas, legumes, and other ingredients identified by the FDA report have not yet been fully studied, the heart of the matter is that no conclusions can yet be made about the underlying dietary cause or causes of taurine-deficiency DCM in dogs. Given what we do know, a recommendation is to feed a food that contains sufficient levels high quality, animal-source protein, does not include plant-source proteins as its primary protein source, and does not contain high levels of dietary fiber. If you are worried about your dog’s taurine status or heart health, see your veterinarian for a complete physical examination and if needed, to measure plasma levels of taurine.

Cited Studies:

  1. Pion PD, Kittleson MD, Rogers QR, et al. Myocardial failure in cats associated with low plasma taurine: A reversible cardiomyopathy. Science 1987; 237:764-768.
  2. Earl KE, Smith PM. The effect of dietary taurine content on the plasma taurine concentration of the cat. British Journal of Nutrition 1991; 66:227-235.
  3. Hickman MA, Morris JG, Rogers QR. Effect of processing on the fate of dietary taurine in cats. Journal of Nutrition 1990; 120:995-1000.
  4. Hickman HA, Morris JG, Rogers QR. Intestinal taurine and the enterohepatic circulation of taurocholic acid in the cat. Advances in Experimental Medicine and Biology 1992; 315:45-54.
  5. Freeman LM, Rush JE, Brown DJ, et al. Relationship between circulating and dietary taurine concentrations in dogs with dilated cardiomyopathy. Veterinary Therapeutics 2001; 370-378.
  6. Backus RC, Ko KS, Fascetti AJ. Low plasma taurine concentration in Newfoundland dogs is associated with low plasma methionine and cysteine concentrations and low taurine synthesis. Journal of Nutrition 2006; 136:2525-2533.
  7. Ko KS, Backus RC, Berg JR, et al. Differences in taurine synthesis rate among dogs relate to differences in their maintenance energy requirement. Journal of Nutrition 2007; 137:1171-1175.
  8. Fascetti AJ, Reed JR, Roger QR, et al. Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997 – 2001). Journal of the American Animal Veterinary Association 2001; 223:1137-1141.
  9. Delaney SJ, Kass PH, Rogers QR, Fascetti AJ. Plasma and whole blood taurine in normal dogs of varying size fed commercially prepared food. Journal of Animal Physiology and Animal Nutrition 2003; 87:235-244.
  10. Torres CL, Backus RC, Fascetti AJ, et al. Taurine status in normal dogs fed a commercial diet associated with taurine deficiency and dilated cardiomyopathy. Journal of Animal Physiology and Animal Nutrition 2003; 87:359-372.
  11. Ko KS, Fascetti AJ. Dietary beet pulp decreases taurine status in dogs fed low protein diet. Journal of Animal Science and Technology 2016; 58:29-39.

A Taste for Meat?

The issue of how to classify the dog and how to best feed dogs continues to be a highly controversial topic among dog people. If you doubt this, just try posting this statement in a dog feeding chat group:

Dogs are omnivores and can thrive on a wide range of diet types.

Good luck surviving the night.

I discuss the current science regarding the dog’s classification in “Dog Food Logic” and in the Science Dog essay “Dogs are Carnivores, Right?“. (Spoiler alert: Dogs are omnivores). Regardless of what the science tells us, there is continued belief in statements such as these:

Dogs are obligate carnivores” [sorry, not];

“Dogs require meat in their diet” [no again]; and

Dogs naturally crave the taste of meat” [okay……this one may have some legs].

Anyone who lives with and trains dogs is aware that dogs are almost universally attracted to meaty foods and treats. Trainers use these preferences to select different levels of “treat value” for dogs and almost invariably, the treats that are of highest value to a dog are those that have a meaty texture, smell and (we assume) taste. It is also true that most dogs are highly attracted to and readily consume high protein diets that include cooked, extruded or raw meat of various types. So, are these preferences a reflection of the dog’s predatory past (wolf ancestors)? If so, are  such preferences something that dogs are born with or is there a strong influence of learning and environment on our dogs’ apparent “taste for meat“?

A recent set of experiments conducted by researchers who study free-ranging dogs in India asked these questions and provide us with some new information.

The Diet of Free-Ranging Dogs: Free-ranging dogs exist in numerous countries around the world, including Mexico, Italy, Nepal, Japan, many African countries, and India. They survive almost entirely by scavenging and occasionally augment their diet by begging and hunting small animals. In India, the history of free-ranging dogs is well-documented, extending back to the 9th century BC and representing more than 1000 generations of dogs.

FREE-RANGING DOGS SCAVENGING GARBAGE

Indian free-ranging dogs consume a diet that is rich in carbohydrate (biscuits, bread, rice) and relatively low in protein. The protein that is consumed is in the form of scraps of meat or fish adhering to bones, decomposing meat, and the remains of carcasses.  Domestic dogs are better adapted to scavenging and a diet that is higher in carbohydrate foods than were their wolf-like ancestors because of changes in foraging behavior (increased scavenging/decreased pack hunting) and enhanced ability to digest starch (increased copies of the gene AMY2B, the gene that codes for pancreatic amylase). However, just because dogs can consume and digest diets that contain a high proportion of carbohydrate (starches), it does not necessarily follow that they prefer such diets or that it is the healthiest or best way to feed them.

Although there are multiple questions here, the two that the Indian researchers attempted to answer were: “Do dogs have a strong preference for meat in their diet?” and if so, is such a preference innate (i.e. puppies are born with this preference) or is it reliant upon or strongly influenced by learning?

Do free-ranging dogs show a preference for meat? In the first study, the researchers offered 30 free-ranging dogs a variety of food choices in four separate experiments. In the first, dogs chose between bread, bread soaked in water, and bread soaked in chicken broth. They selected between bread, bread soaked in gravy, and cooked chicken in the second experiment. The third offered the dogs choices between dry dog kibble or bread soaked in varying concentrations of chicken broth. The final experiment offered the dogs varying combinations of bread and dog food kibble, soaked with different concentrations of chicken broth. The purpose of this final set of choices was to separate the factors of meat smell from nutrient (protein) content, because dogs have been previously shown to be capable of self-selecting a diet according to its macronutrient (protein/fat/carbohydrate) content (3,4 [more about these studies soon]).

Results: The following preferences were found in the adult, free-ranging dogs:

  • Meat (smell) beats carbs: The dogs consistently chose bread soaked in chicken broth over dry bread or bread soaked in water, even though chicken broth contains only a small amount of actual protein. They also selected chicken meat first over chicken-soaked bread or dry bread, when allowed to choose visually.
  • Smell beats all: When the dogs were offered kibble (high protein food) or bread (low protein food) soaked with varying concentrations of chicken broth, they consumed all of the foods equally, showing no absolute preference in terms of the quantity that was consumed. However, the order of selection depended completely upon how much chicken broth was soaking the food, regardless of its nutrient content. In other words, the dogs chose according to smell, not in accordance with the actual amount of meat protein present in the food.
  • “Rule of Thumb”: The cumulative results of the four experiments support the existence of the following rule of thumb for food choice: “Choose the food that smells the most intensely of meat first.” This means that the dogs preferred foods that smelled of meat (but that were not necessarily good sources of protein) over those that smelled less meaty, even when the less meaty smelling foods actually contained more meat ingredients and a higher protein content. This of course, makes sense, since in nature, a stronger meat smell is highly correlated with high meat and protein content and invariably predicts higher meat quantity. This relationship only becomes skewed when clever experimenters enter the picture and mess with it.

The authors conclude that while domestic dogs have adapted a scavenging lifestyle, they appear to have done so without giving up a strong preference for meat. They suggest that while the domestic dog has indeed evolved to more efficiently digest carbohydrate and exist on a carbohydrate-rich scavenged diet, they continue to be strongly attracted to the smell of meat and preferentially select meat-smelling foods. (Not surprising at all to most dog owners; but again, good to have science backing up experiences and beliefs).

But wait, they are not finished. The same researchers then asked……”So, are domestic dogs born with this preference for meat or is it a learned trait?” Using a clever design, they found out:

The Study: The researchers conducted the same series of the experiments described above with the puppies of free-ranging dogs.  The puppies were 8 to 10 weeks of age at the time of testing.

Results: Here is what they found:

  • Puppies did not discriminate: Unlike the adult dogs, puppies near weaning age showed no clear preference for foods that smelled strongly of meat and chose each food selection equally, regardless of how intensely it smelled of meat.
  • Sniff and snatch strategy: While the adult dogs tended to first inspect (smell) all available food choices before choosing and consuming one, puppies did not show this behavior. Rather, they would smell a food, eat it and then move to the next food, showing little to no preference. The vast majority (89 %) of choices made by puppies followed this behavior pattern.

The authors speculate that because puppies consume a protein-rich diet in the form of their mother’s milk, there is little selective pressure for an innate selection bias towards the smell of meat. It is only after weaning, when pups begin to scavenge, that preferentially selecting foods that smell like meat (and are correlated with a high protein content) becomes important. They suggest that, as has been shown in a number of other species, puppies learn their food selection preferences from the mother (i.e. cultural transmission of knowledge) and then as they mature and begin to scavenge, operantly.

Take Away for Dog Folks: The first study’s results with adult, free-ranging dogs tell us that the dogs in this set of experiments were selecting foods based primarily on smell rather than an ability to discern actual meat content. The adult dogs were operating under the (pretty efficient) rule of “If it smells like meat, eat it” (We all know and love dogs who do this…..). This strategy is probably strongly selected for in an environment in which resources are limited, there are few energy and protein-dense foods available, and competition between dogs is high.  This is not really a surprising result – except for the fact that the authors found that the scent of meat was more important than the actual meat (or protein) content of the food. Newly weaned puppies, on the other hand, lack this choice bias and appear to learn to choose “meaty” foods after weaning, either from the food choices of their mother, operantly, or most likely, a combination of the two.

So, what does this tell us about feeding our own dogs? Well, perhaps most importantly for all of you who enjoy a good internet scuffle, these results suggest that while dogs are predisposed to enjoy the taste of meat ingredients and clearly prefer these foods, puppies do not appear to be born with an attraction to the smell of meat per se and these preferences are influenced by learning early in life. On a practical level, these data, along with those of earlier studies of taste preferences in dogs and other species, tell us that the foods that are offered to a puppy at a young age should be expected to strongly influence the pup’s food and taste preferences as an adult dog.

Cited Studies:

  1. Bhadra A, Bhattacharjee D, Paul M and Ghadra A. The meat of the matter: A thumb rule for scavenging dogs. Ethology, Ecology and Evolution 2016; 28:427-440.
  2. Bhadra A and Bhadra A. Preference for meat is not innate in dogs. Journal of Ethology 2014; 32:15-22.
  3. Hewson-Hughes AK, Hewson-Hughes VL, Colyer A, Miller AT, McGrane SJ, et al. Geometric analysis of macronutrient selection in breeds of the domestic dog, Canis lupus familiarisBehavioral Ecology 2012; 24:293-304.
  4. Roberts MT, Bermingham EN, Cave NJ, Young W, McKenzie CM and Thomas DG. Macronutrient intake of dogs, self-selecting diets varying in composition offered ad libitum. Journal of Animal Physiology and Nutrition

If you enjoy reading The Science Dog, take a peak at Linda Cases’ newest book, “Dog Smart: Evidence-based Training with The Science Dog“!

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.

 

 

 

Air, It’s What’s for Dinner

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

Confused

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

Stealing food

HUNGRY…….WANT SANDWICH……

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

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

Air Bites

AIR

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

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

High Density Dry Food                Low Density Dry Food

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

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

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

MY FOOD HAS MORE AIR IN IT??? OH, THE HUMANITY.

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

soapbox

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

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

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

Skeptical Dog

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

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

coversnip

 

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.

soapbox

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).

coversnip

 

Treat Please!

One of the things that I love best about training dogs (and there are many, many things to love about training dogs) is that they respond well to so many different types of positive reinforcement. We have a wide variety of “fun stuff” from which to choose that communicates “Yes!!! That is it!! You are SO very, very smart and good!!”. We can use food treats, petting, verbal praise, an opportunity to play tug, a retrieving game, or even a chance to play with a best dog buddy.

 100225T114

YES! I am good AND I am smart!

Food is generally considered to be one of the most, if not the most, powerful and universal primary reinforcer that we use in dog training. This is true simply because most dogs love to eat, (and as far as I can tell anyway, all dogs gotta eat). Social interactions such as verbal praise, petting, and playing are also effective, but dogs seem to vary considerably in their responses to these; some turn inside out for cuddle time while others do better with a rousing game of tug-o-war. The cool thing is that we have food treats, various ways to convey love and affection, and various types of play to use as positive reinforcers to help our dogs to learn.

Still, there continue to be trainers and owners who eschew the use of food treats and insist that dogs respond equally well to praise and petting as they do to food treats.

Food TreatYUMMY……. I DO LOVE TREATS…..

Do they? Recently, Megumi Fukuzawa and Naomi Hayashi of Nihon University in Japan asked exactly this question (1).

The study protocol: The researchers randomly assigned a group of 15 adult dogs to one of three treatment groups. All groups were trained first to do a short sit/stay exercise (baseline training) and then to “come when called” from increasingly long distances. All of the dogs were trained by a single trainer and each group differed only in the type of +R that was used. These were either Food (soft moist dog treats), Stroking (gentle petting on the head and shoulders), or Praise (“good boy/girl!”).

Treat for sitting Petting for sitting Praise for sitting

               FOOD TREATS                             STROKING                                       PRAISE

Their Results: First, all of the dogs learned the tasks successfully. However, the number of sessions to attain proficiency and the response times differed with the type of reinforcer that was used:

  1. When food treats were used to positively reinforce sit and stay, the number of sessions needed to learn the task was significantly less than when praise or petting was used (4.8 sessions for food; 12.8 and 12.4 sessions for praise and stroking, respectively).
  2. When food was used to teach come when called, the response time was significantly faster than when either stroking or praise were used as positive reinforcers. Praise fared slightly better than petting for this exercise, but the difference was not statistically significant.
  3. Interestingly, when the trainer was closest to the dogs during the early “come when called” sessions, the dogs responded almost equally well to all three reinforcers, with food showing a slight but non-significant advantage.

Take Away for Dog Folks:  This study supports what so many trainers know and use daily: Food treats, petting and praise are all effective positive reinforcers with dogs. Using food treats may enhance learning by reducing the number of sessions needed to acquire proficiency and speeds response time. So keep those treats in your bag of tricks – They work great and your dog loves you for it!

Treat Please!TREAT PLEASE!

HAPPY HALLOWEEN FROM THE SCIENCE DOG!

Reference: Fukuzawa M and Hayashi N: Comparison of 3 different reinforcements of learning in dogs (Canis familiaris). Journal of Veterinary Behavior 2013; 8:221-224.