A Few Raw Facts

Raw feeding has increased in popularity in recent years. While still a small portion of the pet food market, raw foods are definitely here to stay. Perhaps more so than any other type of feeding regimen, dog owners who feed raw are highly dedicated to this form of feeding.

To test this premise, try separating a dedicated raw feeder from his or her favorite food.

YES, I KNOW IT’S A TOOTHBRUSH. I COULD NOT FIND A PICTURE WITH A PACKAGE OF RAW FOOD. 

There are several options for owners who choose to feed raw. These include using a homemade recipe, purchasing a base mix that can be added to raw meat, or buying a frozen or freeze-dried complete and balanced product. For all of these forms, many health and wellness claims are being made:

Okay, the last one may be an exaggeration. Everyone knows that most dogs prefer Match.

Is there Evidence? Despite strong belief in these benefits (and the belief that believing strongly [and in all CAPS] makes the benefits more likely to be true), there has been a distinct lack of scientific evidence to support (or refute) them.

Until now. Last month, a group of researchers at the University of Illinois, led by Dr. Kelly Swanson, published research comparing the effects of feeding three types of food to dogs – raw, moderately cooked (also referred to as “fresh cooked”), and extruded (dry).

The Study: A group of eight adult dogs were fed four different diets on a rotating basis (1). Each food was fed for a 28-day period that included an adaptation phase (i.e. gradually switching to the new food), a phase to measure voluntary physical activity level, and a phase to collect total feces and urine output for digestibility calculations. The researchers also measured food intake and collected blood samples for serum chemistry measurements. The four foods that were studied were:

  • Dry (extruded) food (Purina Dog Chow)
  • Raw food (Freshpet Vital Raw)
  • Moderately cooked, fresh food (Freshpet Roasted Meal)
  • Moderately cooked, fresh food, grain-free (Freshpet Vital Roasted Grain-free)

Results: All of the foods were well-accepted by the dogs and the dogs remained healthy throughout the study period. Food comparisons showed the following:

  1. Food Digestibility: There were no significant differences in dry matter digestibility among the foods. The four products had coefficients ranging between 82.6 % [dry food] and 85.1 % [moderately cooked, grain-free]. The digestibility coefficient for the raw food was 83.6 %. It was not more digestible than either the extruded food or the moderately cooked foods. These digestibility values are considered to be moderate – not rock stars, but not poor quality, either.
  2. Protein Digestibility: There were significant differences in protein digestibility among the four foods. Protein in the moderately cooked, grain-free food was significantly higher (94.6 %) than the protein digestibility of the raw food (88.3 %) or the extruded food (85.1 %). The coefficient for the raw food was a bit lower than the researchers expected based upon previous work.  However, a value of 88 % is still a respectable value and considered to be highly digestible.
  3. Poop quantity: Total fecal output (yes, researchers measure these things) was highest when the dogs were being fed the raw diet and lowest when the dogs were consuming the roasted, grain-free food. This difference was substantial – more than 100 grams per day when fed raw compared with 52 grams per day when fed the roasted, grain-free food. These differences became less dramatic (and not statistically significant) when expressed as either dry matter or a proportion of intake. However, the raw food continued to produce more fecal matter than the other products.
  4. Poop quality: All of the diets resulted in acceptable fecal quality. However, when fed the raw product, dogs produced feces that were softer than those produced when being fed any of the other three foods. These feces were still considered within the normal range of “firmness” however. Feeding the mildly cooked food resulted significantly higher fecal concentrations of two by-products of large intestinal protein fermentation – indole and phenol. The cause or health significance of this is not completely understood, but these two compounds are one source of “stinky poops” that owners may complain about.
  5. Gut microbes: All four of the products caused modifications in the intestinal microbiota. When dogs were consuming the raw or the moderately cooked, grain-free diets, overall microbial population diversity was reduced compared to when they were consuming the extruded food. Fecal microbial shifts that occurred in response to the raw or moderately cooked foods,  which were high in protein and fat, were similar to the shifts that have been reported in human subjects consuming high-protein/high-fat diets. The researchers noted that these shifts – reduced species diversity, increased Fusobacteria and Proteobacteria, and decreased Actinobacteria – are in agreement with other recent reports of the effect of a raw diet on the dog’s gut microbiome (2,3,4). While this shift is generally considered to be negative in terms of health, all of the dogs in this study and others remained healthy while consuming the test diets. Therefore, the long-term effects of these changes are not known and require further study.
  6. Overall health: The dogs in this study remained healthy, had blood chemistry values within normal ranges, and showed normal activity levels.  All of the products were well accepted and readily consumed. It is worth noting that more calories (kcal) per day were consumed when dogs were fed the raw food compared with then they were fed the extruded diet (1202 kcal/day vs. 806 kcal/day). This difference probably reflects the high palatability of the raw diet but also suggests that overconsumption of calories may have developed over long-term feeding of the raw food.

Take Away for Dog Folks: This study found that dogs accepted all three types of foods – extruded dry, moderately cooked, and raw  – and remained healthy. Contrary to expectations (and claims), the raw food that was tested in this study was not significantly more digestible and did not result in less defecation or produce better quality feces. Although all four foods altered gut microbial populations, the shifts caused by the raw food are generally considered to be negative changes rather than positive. However, the complexity of the gut microbiome coupled with numerous factors that affect gut health prevent any conclusions about these changes.

So, where do we now stand with the claims box, above? Here you go:

Before the raw feeders come out in droves……..let me add a few points……

JUST A COUPLE THINGS……

  1. This study tested four commercial foods. The dry, extruded product was Purina Dog Chow; the two moderately cooked foods and the raw food were Freshpet diets. All of these products are mass-marketed pet foods that are sold in supermarkets and are generally considered to be low to moderate in price point.
  2. We can only make conclusions about these foods – this is why the chart above states “no support” rather than “disproven”. The results of this study are based upon the foods that were compared and suggest that, given the information that we now have, certain blanket claims about raw foods are not supported. Clearly, this cannot and should not be extrapolated to all raw diets or all dry foods.
  3. Still……these results ARE important because they show that a dry food performed similarly to a raw and a moderately cooked food. My two cents? This probably has more to do with the type and quality of the starting ingredients that were used in these products much more than it has to do with raw versus cooked. By AAFCO definition, the term “chicken” can (and usually does) refer to chicken carcasses that remain after the removal of chicken meat for human consumption. These carcasses may either be processed into chicken meal for use in extruded foods or ground up and used in raw or moderately cooked foods. Same stuff, different processing.
  4. Last – The moderately cooked foods performed every bit as well as the raw food in most measures and a bit better on some. These data suggest that perceived benefits of feeding a raw diet over a diet that has been cooked at moderate temperatures are not supported. These data also suggest that there is nothing magical about making sure that a food is RAW. Rather, it is more important to consider the source and quality of the starting ingredients, the degree and severity of processing, and the nutrient content of the food.

(Note: Kudos to the research team for reporting brands. This is highly unusual with pet food studies – the vast majority of published papers do not identify either company or brand of the foods that they are testing).

Cited Studies:

  1. Algya KM, Cross T-WL, Leuck KN, Kastner ME, Baba T, Lye L, de Godoy MRC, Swanson KS. Apparent total-tract macronutrient digestibility, serum chemistry, urinalysis, and fecal characteristics, metabolites and microbiota of adult dogs fed extruded, mildly cooked, and raw diets. Journal of Animal Science 2018; 96:3670-3683.
  2. Beloshapka An, Dowd SE, Duclos L, Swanson KS. Comparison of fecal microbial communities of healthy adult dogs fed raw meat-based or extruded diets using 454 pyrosequencing. Journal of Animal Science 2011; 89; 89(E-suppl):284.
  3. Sandri MS, Dal Monego G, Conte S, Sgorlon B, Stefon B. Raw meat based diet influences faecal microbiome and end products of fermentation in healthy dogs. BMC Veterinary Research 2017; 13:65.
  4. Bermingham EN, Maclean P, Thaoma DG, Cave NJ, Young W. Key bacterial families (Clostridiaceae, Erysipelotrichaceae and Bacteroidaceae) are related to the digestion of protein and energy in dogs. PeerJ 5:e3019 https://doi.org/10.7717/peerj.3019  

 

Mind Your Peas and Potatoes

The source and quality of a food’s protein sources are important features to consider when selecting a dog food. Dog folks who care about these things often agonize over how to differentiate among foods in terms of both protein level and quality. These concerns are justified because the protein ingredients found in pet foods vary dramatically.

However, while we all like to talk about protein quality, what exactly do we mean by that term?

What IS protein quality, anyway? A few basics:

  • High quality proteins supply essential amino acids: The protein in a dog’s diet provides the essential amino acids (EAA), plus a source of nitrogen. Essential amino acids must come from a dietary source and are used for growth, tissue repair, muscle development, support of the immune system and a wide range of metabolic functions. A protein that is classified as high-quality supplies all of the EAA in proportions that are close to the dog’s requirements. Conversely, lower quality protein sources are limiting (i.e. have low levels) in one or more of the EAAs.

HERE’S A MEMORY AID FOR YOU……

  •  High quality proteins are digestible: In addition to supplying EAAs, high quality proteins will also be highly digestible. Conversely, low-quality pet food proteins are those that are either low in digestibility, limiting in one or more of the essential amino acids, or both.
  • Measures of protein quality: Nutritionists use several methods to evaluate a protein source’s quality. Some of these, such as chemical score, EAAI and E/T (see below), are conducted in the laboratory and do not involve feeding the protein source. Others, such as PER, BV and NPU, involve feeding trials with a test species (usually growing chicks). Each of these methods, like many things in life, have specific strengths and limitations. Most nutritionists agree that using several measures provides the best overall assessment of a given protein source.

From: Case, et al. “Canine and Feline Nutrition; A Resource for Companion Animal Professionals” (2011)

How does this information help pet owners? Sadly, not much. The reason is that the protein quality information that pet owners are provided is abysmally deficient. The following two platitudes continue to be the ONLY recommendations that owners can use:

  1. Select a food that includes a named animal source  (i.e. chicken meal rather than poultry meal) and
  2. Prefer the AAFCO-defined distinction of meals over by-product meals (chicken meal rather than chicken by-product meal).

Unfortunately, these selection criteria do not reliably reflect quality differences among foods. It is a sad state of affairs indeed for pet owners.

The Good News: There is a bit of good news, however. In recent years, a select group of university researchers have been publishing studies that examine pet food protein quality, labeling accuracy, and methodology. Last month, a group of investigators led by Dr. Greg Aldrich at Kansas State University added to this growing body of work with a study that compared a range of protein ingredients that are used in dog foods.

STUDIES! WE NEED MORE STUDIES!!

Why Peas and Potatoes? They included pea protein isolate and potato protein isolate in the study group. These plant ingredients are of interest due to recent reports of a possible association between these ingredients (among others) and the development of dilated cardiomyopathy (a heart disease) in dogs (see “The Heart of the Matter“). Pea and potato protein are relatively new to the pet food scene and have not been studied thoroughly in terms of protein quality or digestibility.

The Study: The researchers evaluated 16 different protein sources. These included various forms of egg protein (the standard by which to compare other proteins), several forms of chicken, a bunch of commonly used plant proteins such as soy and corn gluten meal, and the two newbies, pea protein and potato protein. There is a lot of information packed into this study, so I will attempt to distill this into the facts that are most important for dog folks to know.

Protein Sources: The list below describes the protein sources that are probably of greatest interest (see the entire paper for an inclusive list):

  • Spray-dried whole egg (In certain tests, whole egg is the standard, high-quality protein source to which other sources are compared).
  • Air-dried chicken (Chicken meat dried and cooked in a hot air-drying chamber).
  • Low-temperature, spray-dried chicken (By-product of chicken fat and broth industry; remaining chicken meat is cooked and dried at low temperature and pressure).
  • Chicken meal (Common pet food ingredient; by-product of chicken meat industry; remaining chicken carcasses are rendered [cooked at very high temperatures, dried, and ground into a powder]).
  • Chicken by-product meal (Same as chicken meal, but also contains varying quantities of chicken heads, feet and viscera).
  • Pea protein isolate (New to the pet food scene; cooked and dried protein-containing fraction of yellow peas)
  • Potato protein isolate (Ditto on newness; cooked and dried protein-containing fraction of potatoes).

With the exception of chemical score, the researchers utilized all of the measures of protein quality in the chart above to evaluate each of these sources. They also measured the proximate analysis of the ingredients – protein, fat, mineral (ash), moisture and fiber content.

RESULTS: This paper reported a lot of new information – multiple measures of 16 different protein ingredients. Here are their key findings:

  • Chicken sources: There were several important differences in protein quality between air-dried/spray-dried chicken ingredients and the chicken meal and by-product meal ingredients:
    • Because the original starting materials differed (meat vs. spent carcasses), the air-dried and spray-dried chicken products were significantly lower in ash than chicken meal and chicken by-product meal. This reflected the inclusion of bone in the latter and not in the former.
    • Chicken meal and by-product meal had higher levels of two types of amino acid that are associated with connective tissue and structural proteins. This means that these sources were higher in protein types that are less digestible and less available (i.e. lower quality) than those found in the spray- and air-dried chicken ingredients.
    • Available Lysine (an EAA) was lower in chicken meal and chicken by-product meal than in all of the other proteins tested. Low available lysine is an indicator of protein damage typically caused by the high heat processing used with rendered meals, which leads to the development of Maillard products.
    • Chicken meal and chicken by-product meal performed significantly lower in growth assays when compared to other forms of chicken.
    • Bottom Line? Chicken meal and chicken by-product meal, the two most common chicken ingredients that are used today in extruded pet foods, performed poorly in measures of  essential amino acid availability and growth. By contrast, less heavily processed chicken ingredients scored significantly higher in these measures of protein quality.
  • Potatoes and Peas: These ingredients are of interest because of the increase in their use in commercial dog foods and because of a possible connection with the reported increase in cases of DCM in dogs:
    • Methionine: Methionine (which is a precursor of taurine) was the limiting EAA in potatoes and peas. This was not unexpected, as many plant-based protein sources are low in methionine.
    • EAA measures: Overall, (again as expected), potato and pea proteins are poorer sources of EAA than are egg and some chicken sources. However, in this study, EAA measures for both pea and potato protein were higher than those for the rendered chicken and chicken by-product meals. (Wow).
    • Growth assays: Conversely, potato and pea proteins did not support growth and development well. This was partly because of lower intakes and possibly due to reduced overall EAA availability in plant-based protein sources.

Take Away for Dog Folks:  This study provides needed information about two commonly used dog food ingredients – rendered chicken and chicken by-product meals, and also about two newcomers to the pet food scene – pea protein and potato protein.

The bad news is that, not altogether unexpectedly, rendered chicken meals, regardless of whether they carried the dreaded by-product descriptor, performed quite poorly. Rendered meals, of the chicken variety, are one of the most commonly used protein sources in commercial dog foods. The products that were examined in this study performed worse than egg protein (expected) and worse in terms of EAA measures than several plant-based proteins. Chicken meal and chicken by-product meal were also found to contain comparatively high levels of connective tissue and structural proteins, and to have low available lysine, an indicator of protein damage that occurs during processing.  

Conversely, other forms of chicken – in particular spray/air-dried forms that were cooked at lower temperatures, were found to be much higher quality protein sources. Although not commonly seen in dog foods, these are forms of chicken ingredients that should be on your watch list, as pet food producers continue to search for better quality animal-source proteins to include in their products.

Finally, the peas and potatoes thing. While this study does not provide a complete answer to the DCM connection, it does provide new information about these two protein-supplying ingredients. Pea and potato protein are both limiting in the essential amino acid methionine, which is the precursor of taurine production. Therefore, it is possible that the inclusion of these protein sources in foods, without concomitantly including additional methionine or taurine, may contribute to reduced taurine status in an animal. Like many plant proteins, pea and potato protein require balancing with other protein sources or amino acid supplementation to counteract these EAA deficiencies.

HAULING OUT THE OL’ BOX…..

Of course, this information is only helpful to pet owners if they have access to it. Pet food companies continue to have no obligation to report quality information about their foods to consumers. In fact, AAFCO regulations actively prohibit the inclusion of quality descriptors on the pet food label. Still, many reputable companies do test their foods regularly and will provide measures of food and protein quality to pet owners when it is requested. If you worry about the ingredients in the food that you are feeding, whatever type of food it happens to be, email the company that makes the food and ask.

Be the squeaky wheel.

Demand transparency and more information about the ingredients that are in the foods that we feed to our dogs. If dog owners are expected to accept the claim of “Complete and Balanced”, we should be provided with proof of this claim, including information about the quality of ingredients. It should not be necessary to seek out and read academic journal papers to obtain this information.

Nuff said. Off box.

Cited Study: Donadelli RA, Aldrich CG, Jones CK, Beyer RS. The amino acid composition and protein quality of various egg, poultry meal by-products, and vegetable proteins used in the production of dog and cat diets. Poultry Science 2018; October; pp. 1- 8, https://doi.org/10.3382/ps/pey462

 

 

 

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, despite being 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.

Dogs and Carbs – Its Complicated

The question of how best to feed dogs stimulates great debate and evokes strong emotions among dog folks. (Yes, this an intended understatement). One of the most contentiously defended viewpoints in recent years is that dogs should not be fed diets that contain digestible carbohydrate (starch). Two primary arguments are used to defend this position.

These are:

  1. Dogs are carnivores and have no dietary requirement for carbohydrate; and
  2. Dogs are unable to efficiently digest starch. Therefore, including starch-providing ingredients in dog foods is unhealthy and provides no nutritional value.

Like many persistent beliefs, there is both truth and falsehood in these claims. Let’s start with the first.

Dogs are carnivores and have no dietary requirement for carbohydrate: The first bit is false; the second bit is true. Dogs are classified within the taxonomic order of Carnivora but like many other species within this order, dogs are omnivorous. The term omnivore simply means that an animal consumes foods that are of animal and plant origin (dogs do this) and can derive essential nutrients from both animal and plant foods (ditto). Based upon this definition, animal nutritionists consider the dog to be an omnivore. By contrast, the domestic cat, along with other felid species, is classified as an obligate carnivore. This classification means that cats cannot derive all of their nutrient needs from plant foods and therefore have an obligate need for foods of animal origin in their diet.

The fact that dogs are omnivorous does not signify that they are not predatory (they are), nor that they do not seek out and enjoy eating meat (they do). All that it means is that dogs can consume and derive nutrients from both animal and plant matter. If we consider the dog’s feeding behavior, it is clear that the majority of dogs enjoy and probably prefer to consume meat in their diet. However, they also scavenge and consume a wide variety of food types, including starch-containing foods. Nutritionally, just like bears (who also preferably seek out animal source proteins), dogs are omnivores.

Personally, I am baffled as to why “omnivore” has become a fighting word among dog people. Really? This label does not turn the dog into a carrot-munching, Birkenstock-wearing, canine hippie.

PEACE DUDE. I’M AN OMNIVORE, NOT A FIGHTER

Rather, it simply describes what the dog eats and is capable of deriving nutrients from – meat and veggies. That’s all. Time for us all to calm down about this one. Let’s move on to the second part of this claim – that dogs have no dietary requirement for carbohydrates.

So what about carbs? This part is correct. Dogs, like other animals, do not have a dietary requirement for carbohydrates. However, cooked starch provides a highly digestible energy source to dogs when included in their diet. From a nutrition standpoint, dietary carbohydrate spares protein. This means that when a body uses carbohydrate to provide needed energy, dietary protein is conserved from being used for this purpose and continues to be available for use to provide essential amino acids, build and repair body tissues, and support a healthy immune system. Therefore, including at least some digestible carbohydrate in the diet of dogs is generally considered to be beneficial. The controversy about starch in dog foods revolves more around how much starch is in the food and where that starch comes from, rather than its absolute presence or absence. Dogs can thrive on low-carbohydrate diets provided such diets are balanced and contain all of the essential nutrients. Diets formulated in this way are often highly palatable because of their high proportions of protein and fat. These foods are also generally very energy dense (lots of calories packed into a small volume of food), which means that portion control is important to ensure that dogs maintain a healthy weight.

Let’s move on to number 2 – the belief that dogs are unable to digest starch.

Dogs cannot digest starch. Unequivocally false. Dog efficiently digest cooked starch, just like humans. They cannot digest raw starch and neither can we. Cooking results in the expansion of the small granules that make up starch, which allows digestive enzymes better access and increases digestibility. This is true for humans as well as for dogs, and this fact explains why we generally do not munch on raw potatoes. We actually know the exact degree to which cooking increases digestibility of various starches. Ground grains such as rice, oats, or corn are about 60 percent digestible when fed raw to dogs. Cooking these ingredients increases the dog’s ability to digest them to almost 100 percent! This means that if you feed your dog 100 grams of uncooked oats or rice, only 60 grams will make it into his body to nourish him; 40 grams ends up in the large intestine where microbes ferment some of it, and a lot of that 40 grams ends up in your yard, as feces. Conversely, when cooked, almost the entire 100 grams are digested and absorbed to nourish your dog. Again, not to put too fine a point on this, but the same holds true for humans.

Meet AMY2B: Dogs also have an enhanced ability to digest starch-containing ingredients, a change that has been directly tied to domestication. In 2013, a ground-breaking paper by Erik Axelsson of Uppsala University in Sweden identified a host of genetic changes that occurred as dogs evolved from their wolf ancestors (1). Three of these changes were alterations of key genes that code for enzymes involved in starch digestion, most notably and consistently, one labeled AMY2B. This gene codes for the production of pancreatic amylase, an enzyme that functions to digest dietary starch.

Although variation exists among individual dogs and breeds of differing geographic origin, the increased copies of the AMY2B gene correlate with higher levels of circulating pancreatic amylase in a dog’s blood, which means that higher AMY2B leads to more efficient starch digestion (2,3,4).  On average, dogs have a sevenfold higher copy number of this gene compared with present-day wolves. These changes in the dog’s genetic makeup coincide with the expansion of human agricultural practices and increased reliance upon starch-providing plants in both human and dog diets.

What do dogs choose? It is a fact that domestic dogs are better adapted to scavenging and to a diet that is higher in starch-containing foods than were their wolf-like ancestors. However, just because dogs can consume and digest starch, it does not necessarily follow that a diet that contains a high proportion of digestible carbohydrate is the healthiest way to feed them. One way of approaching this question is to ask the dogs directly.

Historically, nutritionists have viewed diet selection in animals principally from the standpoint of energy balance. The basic assumption was that all animals, including dogs, eat to meet their energy (caloric) needs first. However, in recent years this premise has been challenged. There is evidence that a wide range of species, including many birds, fish, and mammals, will self-select diets containing consistent proportions of the three major macronutrients – protein, fat and carbohydrate, and that they regulate and balance their nutrient intake to maximize lifespan and reproductive fitness. The recognition that macronutrient selection can be a driver for appropriate diet selection has led to several new studies with dogs and cats.

Domestic cats were studied before dogs and were found to consistently select a diet that was high in protein and fat and low in carbohydrate (5). This profile is consistent with that of other obligate carnivores and with the cat’s wild feline cousins. Interestingly, a very recent study with cats found that cats preferentially balanced their diets to a set protein:fat ratio, even when offered foods of different flavor preferences and containing animal- or plant-based protein sources (6). Although flavor and smell were important influences, the strongest factor for food selection appeared to be the total amount of protein in the food, rather than its source.

To date, only two controlled studies have been completed with dogs. In both, dogs have also demonstrated a similar talent to their feline friends for self-selecting the macronutrient content of their diets (7,8). The studies were conducted by different research teams and used somewhat different methodologies, but both reported that dogs preferentially selected diets that were low in carbohydrate, and high in fat and protein. When expressed as a percent of energy, dogs gravitated to a general distribution of 30 to 38 percent protein, 59 to 63 percent fat and 3 to 7 percent carbohydrate. Interestingly, wolves self-select diets that are even lower in carbohydrate –  only about 1 percent. Initially, the dogs in these studies were attracted to very high fat diets, but over a period of several days reduced the proportion of fat and moderately increase protein. An important finding of the most recent study was that when dogs were allowed to choose these dietary proportions over a period of 10 days, they tended to over-consume calories. On average, the dogs gained almost 3.5 pounds in just 10 days of feeding.

Its Complicated: At this point in time, we know that dogs can better digest starch in their diet compared with their wolf ancestors (and with present-day wolves). This increased capability is at least partially due to increased production of pancreatic amylase. We also know that, like us, dogs digest cooked starches very efficiently, but cannot utilize raw starch. We also know that the  inclusion of at least some level of starch in a dog’s diet provides an efficient source of energy (calories). Finally, most recently, we have learned that when given the choice, dogs preferentially select a diet that is low in starch, and that is high in protein and fat. However, self-selection of this type of diet (if fed without portion control) may lead to overconsumption and weight gain.

Still, none of this information provides evidence for the healthfulness of a diet containing some starch versus a diet that contains very low (or no) starch in terms of dog’s vitality, ability to maintain a healthy body weight and condition, development of chronic health problems and longevity. Unfortunately, this has not stopped proponents of low carbohydrate or carbohydrate-free diets from making such claims. The fact that dogs gravitate to a diet that is high in protein and fat and low in starch  is not to be confused with evidence that such a diet has been proven to be healthier or is capable of preventing illness. We simply do not know.

What we need at this point, is evidence of whether or not dietary carbohydrate is harmful, beneficial or, well,  neither. Dogs are generalists after all. It is quite possible that they, like many animals, are capable of thriving on a wide variety of diet types, including those with some level of starch.

Like I said. Its complicated.

Cited References:

  1. Axelsson E, Ratnakumar A, Arendt ML, et al. The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature 2013; 495:360-364.
  2. Arendt M, Fall, T, Lindblad-Toh K, Axelsson E. Amylase activity is associated with AMY2B copy numbers in dogs: Implications for dog domestication, diet and diabetes. Animal Genetics 2014; 45:716-722.
  3. Arendt M, Cairns KM, Ballard JWO, Savolainen P, Axelsson eE. Diet adaptation in dogs reflects spread of prehistoric agriculture. Heredity 2016; 117:301-396.
  4. Reiter T, Jagoda E, Capellini TD. Dietary variation and evolution of gene copy number among dog breeds. PLOSone 2016; 11:e01148899.
  5. Hewson-Hughes AK, Hewson-Hughes VL, Miller AT, et al. Geometric analysis of macronutrient selection in the adult domestic cat, Felis catus. Journal of Experimental Biology 2011; 214:1039-1051.
  6. Hewson-Hughes AK, Colyer A, Simpson SJ, Raubenheimer D. Balancing macronutrient intake in a mammalian carnivore: disentangling the influences of flavor and nutrition. Royal Society of Open Science 2016; 3:160081.
  7. Hewson-Hughes AK, Hewson-Hughes VL, Colyer A, et al. Geometric analysis of macronutrient selection in breeds of the domestic dog, Canis lupus familiaris. Behavioral Ecology 2013; 24:293-304.
  8. Roberts MT, BErmingham EN, Cave NJ, Young W, McKenzie CM, Thomas DG. Macronutrient intake of dogs, self-selecting diets varying in composition offered ad libitum. Journal of Animal Physiology and Nutrition 2018; 102:568-575.

Choosing Kindly – An Excerpt

This week’s Science Dog essay is an excerpt from Chapter 8 of  “Dog Smart: Evidence-based Training with The Science Dog“.

I introduced the previous chapter with a story about starting each orientation class at AutumnGold with a version of the training game. While I emphasized that our students are usually impressed by these demonstrations and immediately catch on to the power of positive reinforcement, I would be remiss to not mention that we do see the occasional “frownie-face” in the audience during these demonstrations.

What I am referring to is the human version of this:

That face, human form, tells us that the student expressing it is not convinced and is usually taking umbrage with the use of food treats to train dogs. Mr. or Ms. Frownie-face invariably raises a hand to utter some version of the following:

“I don’t want to use food with my dog to train him because I want him to work for me out of love [or respect, or because I am alpha, or because I am King Tut, ruler of the world]”

Okay, maybe I made that last bit up. But you get the picture.

While we get the frownie-face and the resistance that accompanies it less frequently than in the past (thank you positive trainers!), we still see it now and again. So, in this chapter we explore evidence for staying, as much as possible, within the positive reinforcement (+R) quadrant of Skinner’s four consequences. I also will provide a means for communicating this information to the doubting Joes, Josephines and Frownie-faces of the world when you encounter them as clients, in classes, or as your neighbors.

Training in the +R Quadrant: I don’t think it is an outrageous claim to assert that the vast majority of people do not want to harm their dogs, either physically or emotionally, in order to train them. Unfortunately, a substantial number of dog owners continue to think that using punishment is the only effective and reliable way to train dogs. These beliefs may arise from continued reliance upon “dog-as-wolf” myths that tell owners they must establish dominance over their dogs, or upon the view that using positive reinforcers in training is synonymous with bribing. (These beliefs are false, as Joe finds out at the end of this chapter). For now though, let’s look at what we know to be true about the aversive control of behavior, commonly referred to as “correction-based” training, versus training methods that focus primarily on positive reinforcement, commonly referred to as “reward-based” training.

Correction-Based Training: Aversive training methods, even if “balanced” with positive reinforcement, rely upon a dog’s natural desire to avoid pain and discomfort. The dog pulls forward into his leash; a collar jerk occurs; the dog moves back into a loose-lead heel position to avoid the discomfort. If a consequence is not sufficiently unpleasant, the dog has no reason to change his behavior to avoid it and learning does not occur. Therefore, by its very definition, a training approach that relies partially or fully on aversive consequences involves causing some level of discomfort or pain to the dog.

In addition to the discomfort that this approach relies upon, there are emotional costs. The basic emotions associated with pain and discomfort in dogs (as in humans) are fear and anxiety. Although proponents of correction-based methods argue that anxiety and fear can be minimized by using the mildest intensity of an aversive that is necessary, there is no evidence that such a level exists. Rather, all of the studies that have examined the use of aversives to control behavior in dogs have reported signs of stress and/or fear as direct results of these training methods (see following section in this chapter for details).

A third problem with reliance upon aversives in dog training is that the exact nature of a dog’s response is not always predictable. Although some dogs move away from an aversive stimulus if there is an escape route available (for example, a dog stops pulling into a corrective collar), others may freeze in place, panic, attempt to run away, or become aggressive. As a result, the risk is that the response of the dog is not always what was intended by the trainer. This is a common problem because applying an aversive only provides the dog with information about what NOT to do, but does not provide information about what TO do. Essentially, the dog is forced to learn through the process of elimination. Negative reinforcement relies on the dog’s ability to select the desired behavior that will allow her to escape or avoid the aversive. Because a variety of behaviors are often equally successful in avoiding an unpleasant consequence – for example, running away or showing aggression – the behavior that is elicited each time a correction is applied may not be the behavior that the trainer was expecting to see.

Finally, because stress is often introduced with the use of negative reinforcement and punishment, the use of correction-based training as a humane approach to training is questionable. In addition to the potential for intentional or unintentional abuse, aversives that are associated with the owner have the potential for damaging the relationship between the dog and his owner. The overuse of aversives or using corrections that are too harsh can cause generalized fear and avoidance as the dog may learn that one behavior that will allow him to avoid discomfort and fear is to simply avoid being near his owner.

No one wants this. Why take the chance when there are better ways? (In the remainder of this chapter, we explore these better ways along with the evidence that supports their use).

“Dog Smart: Evidence-based Training with The Science Dog” by Linda P. Case (2018)

 

 

 

Get Help! Pony is in Trouble!

This year, for her birthday, Alice got a pony. She named him……Pony.

ALLY AND PONY

Pony has rapidly become Alice’s favorite toy. She carries him everywhere, wrestles with him, wrangles him, growls at him, and generally treats Pony quite badly. (Apparently, Ally has not yet been convinced of the benefits of reward-based pony training). Regardless, Pony and Ally have become inseparable.

Until the day that Pony became lost.

It began like any other morning. Mike and I were getting ready to head out the door for a hike with Ally and Cooper. Pete the cat was underfoot asking for his breakfast, and Cooper was waiting by the door.

Ally? Not around. When Mike called her, she came running into the kitchen, stared intently at Mike and then raced back into the living room.

Ahhh……there was the problem. Pony was stuck between the wall and the back of the couch. Ally could not fit back there to reach him. Looking back and forth from Mike to Pony, Ally communicated the seriousness of the crisis and her need for assistance (someone with thumbs). Mike retrieved Pony, there ensued a loving reunion, and all was again good in the world.

ALLY VOWS TO NEVER AGAIN ALLOW PONY OUT OF HER SIGHT

For most dog folks, a pretty normal morning, eh?

Yet, the act of Alice telling Mike that Pony was in trouble, that she knew where Pony was, and that she needed Mike’s help, is considered to be a complex form of communication. It is called referential gesturing and involves both motivation (“I WANT Pony!!”) and intention (“I need your help to get him!”).

Referential Gestures: For a gesture to be considered referential, it must possess these five attributes:

  1. It is directed towards an object or an objective (Pony).
  2. It is mechanically ineffective (Ally running from Mike to Pony cannot save Pony)
  3. It is directed towards another individual (Mike)
  4. It results in a voluntary response by the receiver (Mike saves Pony).
  5. It has intention (Obvious. Pony is in trouble and must be saved).

Pointing: Pointing is one of the most frequently used human referential gestures. Dogs understand and respond to all types of human pointing, such as hand points, foot points, and gaze. (I review these studies in detail in my newest book, “Dog Smart“). However, to date, research studies have focused on the dog’s ability to understand human gestures, rather than the use of these gestures by dogs and our ability to understand and respond to them. Of course, anyone who lives with multiple dogs knows that dogs are masters at signaling the location of a bit of food on the ground, a favorite toy, or (unfortunately) something smelly and suitable for rolling upon to other dogs in the family. Similarly, I bet that any dog owner reading this piece can easily identify one or two ways that their dog uses referential signaling with the humans in their life.

However, most of us probably have no idea exactly how good dogs are at this. They are really, really good……We have some new research that tells us so. Here it is:

The Study: Researchers at the University of Salford in the UK recruited a group of 37 dogs and owners, and used the Citizen Science protocol developed by Alexandra Horowitz and Julie Hecht to collect data. For a period of several weeks, owners filmed their dog performing “everyday” acts of communication with them. Examples included, but were not restricted to, requesting food, asking for a toy, or requesting that a door be opened. A total of 242 communication gestures were recorded and submitted for analysis. The researchers coded and analyzed communicative gestures according to the dog’s perceived goal, frequency of use and interaction outcome (whether the goal was achieved or not). Results: 47 different forms of referential gestures were identified from the submitted video footage. That is a LOT. (Can you think of 47 distinct ways in which you gesture to signal a need to others?). They also found:

  • A Conservative Estimate: When the researchers applied all five of the features identified above, the initial group of 47 gestures was distilled to 19 that were solid and indisputable examples of referential gesturing. That is still a LOT. Altogether, these were used over 1000 times in the collected videos of 37 dogs.
  • What Dogs Ask For (and Get): The four most commonly used and most successful referential gestures were requests for petting/scratching, food or water, to go outdoors, and to retrieve a toy (Pony!).
  • Gaze Alternation: Among all of the dogs, direct gaze and gaze alternation, looking back and forth from the owner to the goal, were by far the most common gestures that were used. Almost 400 instances of referential gaze were recorded, with dogs using eye contact to communicate a wide range of goals.
  • Gesture Portfolios: Dogs varied tremendously in the number and type of gestures that they used to communicate. It was not uncommon for a dog to employ several different gestures (gaze, head turn, pawing, barking) for a single goal and to switch to a new gesture if the first was not successful. Interestingly, dogs who lived with more than one person tended to use a larger repertoire of gestures, perhaps having developed customized ways of communicating with each person.

Take Away for Dog Folks: It is important to put this information in the context of what we know about other animals. The use of referential gestures in species other than humans is considered to be rare. Great apes (chimpanzees, bonobos, orangutans) use one or two forms of referential gesturing with other apes and occasionally, when in captivity, with human caretakers. There are also a few examples of this form of communication in birds and some fish species. But in all of these cases, the gestures are limited to one or two forms and are used only with members of the same species. Cross-species referential gesturing is not a normal part of most animals’ repertoire. Nor is there anything  even close to the wide variety of gestures that dogs use when communicating with us. While we have known for a number of years that dogs are uniquely capable of understanding human communication signals, this is the first study to demonstrate that dogs use a diverse set of  referential signals when they communicate with us and that, just like our dogs, we understand what they are telling us. This is cool stuff.

So, the next time that your dog loses her Pony, pay attention to the type of referential gestures that she uses with you. In fact, take a moment now. Make a list of the different gestures that your dog uses to communicate his or her needs and desires to you. I am betting that there are a bunch. And, while you probably easily understand these and respond appropriately, remind yourself of the degree of complexity and specificity of the communication that is taking place in those moments when your dog loses his favorite toy and asks you for a bit of help.

ALLY REQUESTING A SECOND SUNDAY MORNING BAGEL

Cited Study: Worsley HK and O’Hara SJ. Cross-species referential signaling events in domestic dogs (Canis familiaris), 2018; Animal Cognition,  10.1007/s10071-018-1181-3. 

The Smell of the Blue Ball

A favorite activity of the Case dogs is the “Find It” game. We play this out in the training building and begin by asking the dogs “What’s Hiding Today?”. We all visit the giant toy bin and select a toy for the day’s game. I show the toy to everyone, making sure that each dog gets a good long sniff. The dogs then run to the storage room where they wait as I hide the toy. The door is opened, dogs burst forth into the room and the competition begins! Everyone races around, air scenting, searching every nook and cranny of the room. The first dog to find the toy is the winner, grabbing the toy and running with it to home base to get their prize, a yummy treat.

Mike and I have played this game with our dogs for more than 30 years. While we have seen a range of talent and search strategies among them, all of our dogs adore this game, turn cartwheels to play it and always ask for “one more round” no matter how often we play. In addition to being convinced of the pleasure that dogs take in searching, it has always been obvious that our dogs not only search for the toy using primarily scent (olfaction), but also that they are able to discriminate between toys and will select only that toy that is chosen for the day’s game. For example, if another toy, one that was not chosen, has been left out somewhere in the building, it is summarily ignored, even if that toy has been hidden for the game on a previous day. It has always seemed that our dogs not only have been searching using their noses (not a big surprise of course), but that they are keenly aware of the smell of the blue ball versus that of the red tug toy.

CHIP AND ALICE AND THEIR FAVORITE BLUE BALLS

Picture a Blue Ball: The mental representations of objects is something that most of us take for granted. For example, think of your dog’s favorite toy; for my dogs, this is a blue Planet Dog ball. What mental representation do you conjure? I bet it is a visual representation, correct? (I see the blue ball in my inner brain right now). We may naturally assume that other animals represent their worlds similarly. However, for species such as dogs, whose strongest sense is olfaction, it is quite possible, expected really, that their mental representations of objects may be more strongly olfactory than visual – in other words, the smell of the blue ball.

A recent study examines just this question – Do dogs represent objects as odors?

The Study: Researchers at the Max Planck Institute in Germany used a study paradigm called the “violation of expectation” test. There are various ways to design this test, and in this particular set-up, dogs were asked to track the odor trail of a selected toy. At the end of the odor trail, they found either the expected toy or, big surprise, a different toy! The researchers predicted that if the dogs had an internal olfactory representation of  the selected toy, then finding a different toy at the end of its scent trail would be unexpected and discounted – meaning that they would hesitate or continue to search for the selected toy – just like my dogs do in the find it game. Conversely, if the dog simply grabbed the unexpected toy, this would suggest that although dogs are highly capable of following a scent trail (something that is already well supported and known), they do not have a strong internal scent representation of the scent of a specific object. Given what we know about the dog’s extraordinary sense of smell, the researchers hypothesized that dogs do indeed have very specific and distinct odor representations of objects and that the first scenario would predominate in their test.

The Dogs: They tested a group of 48 adult dogs of varying breeds and with different training backgrounds. Half of the dogs were trained either in search and rescue or police work. The other half were dogs living in family pets who had received no formal training. For each dog, two “high interest” toys of similar size were selected for use in the search tests. Each dog was tested in four randomized conditions in which one toy was dragged along the floor to leave a scent trail and then hidden in a cupboard. The routes and the hiding places were varied and dogs found either the expected toy (i.e. the toy that left the scent trail) or the unexpected toy in two trials each. Each  dog’s searching and sniffing behaviors, time to find the hidden toy, and response when finding the expected or unexpected toy were recorded.

Results: All of the dogs searched for and found the toy successfully within 2 minutes and the majority retrieved the toy after finding it. Sniffing behavior was used to search in the majority of searches (75 %), and most dogs used both air scenting and ground sniffing to find the hidden toy. Dogs found the hidden toy significantly faster when they sniffed versus the smaller number of trials that they attempted to find it visually, without sniffing. Here are other interesting results:

  • Surprise! On the first trial, there was no difference in the amount of time that it took to find the expected versus the unexpected toy, but significantly more dogs hesitated to retrieve the unexpected toy compared to the expected toy. This suggests that the dogs experienced a “violation of expectation”, supporting the hypothesis that they had an internal scent representation of the specific toy.
  • Working dogs vs. pet dogs: On the very first trial, the working dogs searched at higher speeds and were considerably faster at finding the hidden toy than the pet dogs. However, after the first trial (when it is assumed that the dogs “learned the game”), there was no difference in search speed or success between the trained working dogs and the pet dogs.
  • Not just the sniff: Dogs used a combination of both sniffing and visual searching in most trials. Interestingly, they tended to use vision immediately and when the toy was not obvious, such as when it was hidden in peripheral spots, they relied more heavily upon sniffing.

Take Away for Dog Folks: This study provides confirming evidence for something that many of us witness daily with our dogs – that they identify and discriminate among different objects using their sense of smell. But, there is also a bit more here. This study targets cognitive questions about internal representation and how human perceptions, which are primarily visual, may differ dramatically from a dog’s perceptions and representations. When Ally and Cooper compete to find the hidden blue ball, they may know what that blue ball looks like, but the internal image that they have of it is probably not an image at all…..but rather is a smell. The smell of the blue ball.

Can we, as a primate species, even know  what that is like? Probably not, but it sure is cool to attempt to understand it.

Happy Training!

Cited Study: Brauer J and Belger J. A ball is not a kong: Representation and search behavior in domestic dogs (Canis familiaris) of different education. Journal of Comparative Psychology 2018; https://doi.org/10.1037/com0000115.