Anatomy of Eating
Like their huumans, cats and dogs have their own fooding behaviors. When observed closely, you will notice small differences between mutts, pups, masters and nobles. Some research indicate that these differences start right from the food selection step, when the bowl is offered. The whole food selection routine requires organoleptic [see: Wikipedia] attributes of the food such as odor, taste, and texture. In basic terms:
- shape, and
All play a key role in their culinary experience and selection process. Knowing the basic physiology and understanding fooding behavior is a first step to tailoring food to the specific needs of our fur kids. The logical continuation then to satisfy their appetites, is to know their preferences and make sure that the meal possesses all the attributes that will bring about palatability – the “deep dive!“.
Dogs tend to sniff, chooses and eats food rapidly. In general, when presented with multiple options, dogs would stick to the first choice. Cats, on the other hand, sniffs, hesitates, takes time before eating, like reading the menu, perhaps sending a quick text memo via the universe. When faced with multiple options, cats can change their minds several times during the course of the meal.
In a recent studies1 when cats were offered three diets with varying macronutrient profiles, they choose a high-protein, high-fat diet. The total consumption of the three diets by cats, when averaged out, showed that cats preferred protein 50 percent to 52 percent by energy, fat 36 percent to 50 percent by energy, and carbohydrate 2 percent to 12 percent by energy, even though they cannot process or leverage carbs.
How do we get cats to eat kibble? By coating the kibble with “cat crack“. Chemicals called pyrophosphates [see: Wikipedia] are used to coat dry cat food, and are often referred to in the processed pet food industry as “cat crack“. Some manufacturers use a compound mixing pyrophosphate (phosphate salts) with meat hydrolysates as an effective enticer of cats to a food. Meats and their by-products are broken down in water to form meat hydrolysates. Pyrophosphates magnify the taste of the amino acids that remain in the meat hydrolysates – or at least for cats. This magnified taste of protein – though chemically achieved – is what keeps cats addicted to a “cheap pet food” that no one else wants to eat.
In the same type of three-diet-offering study, dogs choose a high-fat, moderate-protein diet 2. The average result for these tests was a preference for 30 percent to 38 percent protein by energy, 59 percent to 63 percent fat by energy, and 3 percent to 7 percent carbohydrate by energy.
Cats and dogs have very sensitive sense of smell. Both are more sensitive to odors than their huumans3 4 . Dogs sensorial and anatomical equipment include 200 million olfactive neurons5 , and 10% of the brain is dedicated to olfaction. Cats include 67 million olfactive neurons, and about 6% of the brain is dedicated to olfaction. In comparison, huumans only muster a mere 15 million olfactive neurons, and only 0.3% of our brains (as percentage of weight) is dedicated to olfaction.
Think of it this way. If we compare our dog’s smell superpowers to vision, then what we as pet parents with good sight can see at 500 meters away, our dogs can see at ~ 4800 kilometers away AND still see it well. Or, put another way, dogs can detect some odors in parts per trillion. What does that mean in terms we might understand? In her book “Inside of a Dog”, Alexandra Horowitz6, a dog-cognition researcher at Barnard College, writes that “while we might notice if our coffee has had a teaspoon of sugar added to it, a dog could detect a teaspoon of sugar in a million gallons of water, or two Olympic-sized pools worth“. Another dog scientist likened their ability to catching a whiff of one rotten apple in two million barrels.
How do we get dogs to eat kibble? Unlike cats, dogs are attracted more to the smell of food than the taste when deciding what to eat, and how fast to gobble it down. So, when our friends in the pet feed industry create artificial flavor coatings for dry dog food, their goal is to develop palatants that cause a dog to “dive in with instant and obvious zeal“.
This response will cause pet parents to assume the food is a hit, when, it might have only smelled like a hit. Kinda like the 70’s One Hit Wonders Singles. Dogs, like huumans, have a sweet tooth, and our friends in the pet feed industry know this to well. Hence the palatability spray also includes a large amount of “sugar-like” or even sugar, substances.
In turn, cats and dogs have limited perception of colors, and have difficulty seeing anything close to them. They can however distinguish objects and shapes and have better night vision. Huumans poses around 7 million cones and 120 million rods in the retina, and have trichromatic color perception. Dogs poses around 3 million cones and 200 million rods, have dichromatic color perception7 , and cats also poses around 3 million cones and 200 million rods, and also have dichromatic color perception Cones and rods are photoreceptors found in the retina. Cones work in full light and allow colors to be seen. Rods work in low light and allow visualization of white and black.
In terms of dentistry, cats have 30 teeth, 4 molars and 10 premolars. Dogs poses 42 teeth, 10 molars and 16 premolars. Huumans, in comparison, poses 32 teeth, 12 molars and 8 premolars.
When considering palatability, then taste comes to play. Unlike cats, who lack the receptor for sweetness8 , dogs can detect the same five tastes as huumans. Dogs poses 1600 taste buds, and can detect sour, bitter, salty, sweet and savory (umami). Cats only poses 473 taste buds, and cannot sense sugar. Cats therefore can sense sour, bitter, salty and savory (umami). Huumans by comparison, poses 9000 taste buds, and can detect sour, bitter, salty, sweet and umami.
Just to reiterate, we are discussing the “why” in our series of articles, not the “how to“.
In late June, 2019, University of California-Davis Professor Frank Mitloehner [see: Mitloehner] tweeted the ingredient list of three food items, two of which were popular plant-based burgers and one of which was “premium dog food”:
Mitloehner later tweeted, was that the two most notable plant-based imitation burgers, Impossible Burgers and Beyond Meat Burgers, were “indistinguishable from dog food.” From a factual standpoint, the three images accurately depict ingredient lists for (from left to right) a Beyond Meat Burger, “Walk About Dog Food” brand “Super Premium” grain-free vegan dog food, and an Impossible Burger.
Keeping it Natural
Hopefully by now your will agree with our hypothesis that even though alpha-amylase is present in most carnivores researched to date (cats, dogs, minks, ferret and fox), the presence of this enzyme does not reclassify our cats and dogs as omnivores. In fact, we believe our adoption of the definitions below is a fair outcome of what we have learned about the features that adapt dogs and cats for digesting proteins and fats from animal sources, and not from carbohydrates and other plant materials:
- cats are obligate carnivores;
- dogs are facultative carnivores.
As the dog’s internal physiology does not differ from the wolf, or the fox for that matter, dogs and cats still have the same physiological and nutritional needs as their wild predator cousins. It does raise the question of which foods are appropriate for their carnivorous anatomy, and which are not?
“Modern” dogs, irrespective of breed or country of origin, are not only capable of eating the food of their wild cousins, but actually require it for maximum health. This is because their basic physiology has changed very little with domestication – despite the obvious differences in their physical appearances.
Complexity sells, simplicity does not. Neither is simple sexy. What we are advocating is simplicity in itself, a biologically, species appropriate, real food diet. Biologically appropriate in this context just means food as designed to match the digestive anatomy of your fur kids. It should be clear by now that large quantities of grains, starches and carbohydrates are certainly NOT biologically or specie appropriate.
In it’s basic form, this prescribe a diet:
- rich in animal protein from real meat;
- could include a variety of protein sources;
- should be low in carbohydrates;
- essential fats from animal sources, and not plants;
- botanicals can include fruits and vegs, preferable fermented.
From our observations of the pet feed industry (McKibble and McCan), any concept of reducing protein in McKibble and McCan is clearly tied to reducing ingredient costs, rather than to any concern for health in our fur kids.
- While high protein diets were once believed to be associated with kidney disorders, clinical studies have time and again demonstrated that no association exists between high protein diets and kidney disease.
- The myth that high protein diets are harmful to kidneys probably started because, in the past, patients with kidney disease were commonly placed on low protein (and thus low phosphorus) diets.
- Science has since shown that for patients with kidney disease the concern is rather protein quality, not protein quantity.
- The ability of excess dietary protein to induce kidney failure has been studied in both dogs already with chronic kidney failure, dogs with only one kidney, and older dogs. All studies conclude that high protein does not adversely affect the kidneys.
- Dietary protein consumed in excess of daily requirements is not stored, but is deaminated followed by oxidation of the carbon skeleton through pathways of glucose or fat metabolism. The nitrogen waste generated is excreted in the urine as either urea or ammonia.
- There is also no direct link between high protein and skeletal development of puppies and growing dogs of any size or breed. It is calorie intake and mineral intake – NOT PROTEIN INTAKE – that directly correlates with orthopedic problems in growing dogs.
- Protein restriction for healthy older dogs is not only unnecessary, it can be detrimental. Protein requirements actually increase by about 50% in older dogs, while their energy requirements tend to decrease. When insufficient protein is provided, it can aggravate the age-associated loss of lean body mass and may contribute to earlier mortality.
Just as the ocean tides pulse through its ebb and flow motions, so does the relationship between carbs and protein in the commercial McKibble and McCan dietary framework. There is a relationship embedded in the framework between the amount of protein and the amount of carbs. If one goes up, the other must come down. The more protein in the food, the less carbs are present, and this is good for your pack. Protein is essential, and cannot be oversupplied, but carbs can be oversupplied, ignoring the fact that carbs are not needed.
Protein and carbohydrates contain exactly the same number of calories (potential energy) per gram, so reducing protein in favor of carbohydrates simply provides less nutrition without changing the calories.
The Dog Food Nutrient Profiles published by Association of American Feed Control Officials (AAFCO, 2008) show that dogs have absolutely no requirement for carbohydrate. For cats, carbs are a no no.
According to the National Research Council’s Committee on Animal Nutrition (2006), “there appears to be no requirement for carbohydrate provided enough protein is given”.
Variety is the spice of life, and was the basis of the dietary framework that helped along evolutionary adaptations in our fur kids. From day-to-day, week-to-week, the foods eaten would have varied widely from a nest of pheasant eggs to the remains of a herbivores carcass, a duck, a rotting fish next to the river. This natural variety is lost in conventional dogs or cat feeds today (McKibble and McCan), which typically focus on single source proteins.
Real Protein Required
Real protein is the staff of life for our fur kids – essential to basic body functions, including cellular regeneration, tissue maintenance, hormone and enzyme production, and the provision of energy. Although protein is essential, not all proteins function equally, with protein qualities varying enormously between various sources.
Three factors effecting protein quality include:
Due to the different amino acid profiles contained in animal and plant proteins, animal proteins are considered “complete proteins” for dogs and cats, while plant proteins are considered “incomplete proteins“.
Animal proteins contain all of the amino acids essential to dogs and cats in quantities that match the requirements needed for their overall health, maintenance and growth.
Plant proteins such as corn gluten, soybean meal or plant protein isolates, do not contain all of the amino acids in the right proportions that a dog or cat needs. Amino acids essential to dogs and cats often missing in plant proteins, include arginine, taurine, methionine, lysine and tryptophan.
Protein digestibility is another key quality measure. After all, what good is it to have a food made with a higher quality protein if it is not also easy to digest? A food with high protein digestibility is one that can be broken down into smaller easy-to-absorb components easier and quicker than others. In the short digestive systems of dogs and cats, plant proteins are far less digestible than meat proteins. For our dogs and cats, animal source protein is the best choice – it is easily digested and contains the amino acids essential for dogs and cats.
There has been a long-standing story among veterinary nutritionists about “Old Shoes”. Old Shoes, made of leather, when analyzed in a lab will be high in protein. But our canine athlete cannot thrive on old shoes.
Real Fat Required
While often viewed negatively by health conscious huumans, fat is an essential dietary requirement for dogs and cats. As huumans are concerned with reducing fat intake, we often fail to realize the essential role that fat plays in the diets of our fur kids, or our own for that matter.
Just as with protein, fats are also not created equally and differ greatly in their component structure and quality. Dogs and cats do not suffer from cholesterol problems or heart disease caused by higher levels of animal fats, and it should come as no surprise that cats and dogs need fat from animals, rather than plant source. The reason for this is that dogs and cats have more good cholesterol (HDL) than bad cholesterol (LDL) no matter what types of fat they eat 9. It is therefore not necessary to categorize different types of fats as either good or bad for our fur kids. Cats are likely similar to dogs in this regard although definitive data other than the fact that cats have high HDL cholesterol has not been obtained yet.
In view of these metabolic differences, the we adopt the categorization of the various types of dietary fats for dogs and cats as either “functional” or “facilitative” (helpful, not to be confused with facultative).
Two key roles of dietary fat are:
- Providing a concentrated source of energy;
- Supplying the Essential Fatty Acids (Omega-3, for example) that dogs and cats cannot produce within their own body10.
Both dogs and cats require a fairly high amount of animal fat in their diets for energy. As companion dogs and cats enjoy a more sedentary lifestyle than their carnivorous cousins, moderation of fat is important. Except, of course, for our canine athlete.
While both fats and carbohydrates provide energy, they function very differently in the body of a dog or cat. Fats are essential in the diets of dogs and cats, carbohydrates are not11. Carbohydrates (glucose) provide energy more rapidly compared to fats in huumans, and for us, a high intake of carbohydrates increases muscle-glycogen, which increases stamina.
The same carbohydrate loading in dogs creates an excess accumulation of lactic acid in the muscles, leading to a condition called hypoglycemia, which causes weakness and fatigue.
Essential fatty acids are the fatty acids present in fats that are required by the body. Because they cannot be produced in the body, Essential Fatty Acids must come from foods. The most important are linoleic and arachidonic4 (Omega-6), and DHA and EPA (Omega-3). An appropriate balance of omega-6 and omega-3 is important as these two fats work together. Current research indicate that a ratio of 2:1 to 5:1 (or between 5:1 and 10:1 depending on which publication is referenced) is generally accepted as ideal for dogs and cats, but the ideal amounts and ratio of the two is still unknown. A lack of Omega-6 is extremely rare, but most pet feed (McKibble and McCan) have too much Omega-6 and not enough Omega-3.
Facts about Fats:
- Saturated Fats (vegetable and animal fats)
- short chain; produced when dietary fiber is fermented in the colon (grains, beans);
- medium chain; coconut oil, palm oil;
- long chain; beef fat, butter, cream;
- Polyunsaturated Fats
- Monounsaturated Fats
- Omega 9 – OA, oleic acid (olive oil, canola oil, avocado oil, sunflower oil, sesame oil, almonds)
As with protein, Omega-3 quality varies dramatically between plant and animal sources. Of the 3 kinds of Omega-3: ALA (alphalinolenic acid) is from plants, while DHA (docosahexaenoic acid) and EPA (epicosapentaenoic acid) are from fish.
It is therefore our understanding that dogs and cats require DHA and EPA, not ALA.
Plant source Omega-3 is ALA, a short-chain omega-3 found in some other plant oils sources such as flaxseed (linseed), with lower amounts in walnut, canola, soy and animal sources like fish oil (cold water fish as salmon, cod and mackerel). ALA must be converted to EPA and DHA to be of any nutritional benefit to a dog or cat. Some species, like huumans and dogs, can convert ALA into DHA and EPA but the process is not very efficient. In the 1970’s experiments on feline fatty acids (EFA) metabolism concluded that cats cannot make the conversion at all. Therefore, to provide the most helpful omega-3 fatty acids to dogs and cats, you should use fish-based resources (which contains EPA and DHA) rather than flax, chia, or other plant-based omega-3 fatty acid sources. Animal Omega-3s (EPA and DHA), for example from fish, are long-chain omega-3s that are absorbed readily and directly within the body. Naturally present in oily fish, EPA & DHA and are by far the best Omega-3 choice for dogs and cats.
ALA Omega-3 from plants is considered “inactive” and not biologically appropriate for dogs and cats. While dogs are able to produce arachidonic acid from linoleic acid, cats cannot synthesize arachidonic acid and require it in their diet.
Our fur kids’ metabolism is much more effective than the huuman metabolism when it comes to dealing with fat. What we have learned thus far:
- What is good for you could be very bad for your dog and (as we’ve learned with carbohydrates) vice versa!
- Unlike us huumans, dogs and cats don’t suffer from atherosclerosis or heart disease caused by high levels of animal fats.
- Fat is a very important part of dog and cat nutrition, providing a concentrated source of energy and supplying essential fatty acids (EFAs) not otherwise synthesized in the body.
- Dogs and cats require a fairly high amount of fat in their diets
- What is ‘essential’ for one species of animal is not necessarily essential for another species. For example, the fatty acid, arachidonic acid is essential for cats but not for dogs.
- The two essential fatty acids that are most commonly discussed for nutrition are Omega 6 fatty acids, and Omega 3 fatty acids.
- A lack of Omega-6 is extremely rare. Most McKibble and McCan have too much Omega-6 and not enough Omega-3.
- Omega-3 quality varies dramatically between plant and animal source.
- ALA can be converted into EPA; however, it is inefficient at converting to DHA, especially during times of growth and reproduction.
Do we need fruits & veggies in the diet?
A more contested element of the current nutritional debate involves fruits, veggies and botanicals in the diet. For most traditional manufacturers of McKibble and McCan, the use of carbs and starches in the production process provide the structure or glue required to keep the meats and fats together. Your PMR (prey model) fooding fans believe that there should be no form of fruits, veggies or botanicals in the diet. For the steadfast BARF-fooders, the inclusion of fruits and veggies is perfectly acceptable. The current thinking is that up to 30% of the daily meal allowance can have fruits and veggies. The inclusion of botanicals is also controversial, but many are now studying the concept of deliberate self-medication by animals of all sorts, field called Zoopharmacognosy [see: Wikipedia].
Sick animals tend to forage plants rich in secondary metabolites, such as tannins and alkaloids. Since these phytochemicals often have antiviral, antibacterial, antifungal and anti-helminthic properties, a plausible case can be made for self-medication by animals in the wild.
For the purpose of our hyopthesis, we want to understand:
- if fruits and veggies are required, and if so, what types;
- is their any research to validate the requirement;
- we know that our athletes’ wild cousins often include non-animal sources of foods in their diet, how relevant is this to our hypotheses.
Our observation is that when fruits, veggies or botanicals do form part of the wild cousins diet, it would be ingested via the stomach contents of they prey. This then leads us to the conclusion that fruits, veggies and botanicals should be fermented to form part of our hypothesis.
Dr Karen Becker published an article on this topic back in 2014, titled ” Fermented Vegetables: Finicky Pets Might Not Like This Superfood, But It’s a Potent Cancer Fighter“13 , in which she surmise:
- Dogs, and to a lesser extent cats need vegetables for the roughage, phytonutrients, and antioxidants they provide, which mimics what would be found in their prey’s digestive tracts.
- One of the best ways to provide vegetables to pets is by fermenting them. Fermented veggies are optimally digestible for dogs and cats, and they also offer powerful probiotic benefits.
- Fermented vegetables are also potent chelators and detoxifiers, and the fermentation process makes the nutrients inside the veggies more bioavailable14. Also, the lactic acid produced by fermentation is a chemical repressor that fights cancer cells without harming healthy cells.
From our understanding, fermentation is really where chemistry meets nutrition15. Fermentation occurs as a result of oxidation causing a “release of energy to produce organic acids, gases, and / or alcohol,” or the food is already slightly pre-digested and broken down before your athlete eats it.
Why are fermented foods often nutritionally superior? Because they contain loads of probiotics (beneficial bacteria for gut health) and more available nutrients (cells have been broken down by enzymes and microorganisms). They are also alkalinizing to the body, which creates an inhospitable environment for cancer cells.
We will keep this topic open, as we could easily transition into pre- and probiotics, gut microbiota and many other rabbit holes.
Do we need carbs in the diet?
The largest contribution to the current debate about biologically, specie appropriate dietary frameworks for cats and dogs is indeed the inclusion carbs and starches in the current formalizations for McKibble and McCan.
Carbohydrates, or rather glucose (in our simplistic understanding of a very complex topic), is usually the first source of energy available to the body given current understanding. However, as we highlight in our articles on Energy Systems and Needs, it is not carbs per say that is the provider of energy, but instead glucose. Proteins and fats also provide energy but glucose are called upon first by our understand of huuman energy systems. According to the NRC guidelines, “Carbohydrates provide an economical source of energy in the diet of dogs“. It is a little misleading, as glucose potentially provide an economical source of energy in the diet of dogs.
Carbohydrates are divided into two broad groups:
Simple carbohydrates (monosaccharide) are made up of single sugars, or two sugars joined together and are found in grains such as corn, wheat and rice. Simple sugars are quickly absorbed into the blood stream, causing a rapid rise in blood sugar levels. This rapid rise causes the body to produce a sharp rise in insulin levels and results in the sugars being converted into fat. The rapid rise in blood sugar levels is usually followed by a rapid drop, leading to feelings of hunger and weakness.
Complex carbohydrates (disaccharide), on the other hand, have more than two units of sugar joined together and are found in potatoes, beans, as well as many other vegetables and fruits. Complex carbohydrates can take a long time to break down in the stomach or pass through undigested, creating voluminous stool.
Did you know that the most common types of carbs found in McKibble and McCan are the di- and polysaccharides. Despite the variety of carbohydrate sources that can be eaten and digested by dogs, the greatest majority of these carbs are digested and / or broken down into the simple sugar glucose.
The question the current raging debate is trying answer, unravel or justify, is whether or not carbohydrates are appropriate for carnivores. This debate, in part, was sparked due to the presence of the alpha-amylase enzyme detected in the species “dog”.
Dogs and cats have no nutritional need for carbohydrates and are evolved to use protein and fat as energy sources. That the “omnivorous” dog physiologically tends highly carnivore, due to his digestive abilities and nutrient requirements, has been known since the dog was first used as a laboratory animal. The earliest published scientific paper we have been able to find stating this was written by Cowgill, G. R., 1928: “The energy factor in relation to food intake; experiments on the dog“. Amer. J. Physiol., 85, 45–6416 . The pet food industry, AAFCO, the US National Research Council (NRC), all serious text books and reference material provided to hopeful vet school students … none deny that carbohydrates are not required by the dog. It is also agreed that the most efficient source of all required nutrients is animal tissue.
The natural diet contains almost no carbohydrate at all, and the small predigested grains, fruits & vegetables in the stomach of a prey animal make up a very small fraction of the total diet.
Today’s high carbohydrate McKibble and McCan lead to blood sugar fluctuations, insulin resistance, and are widely considered as a leading cause of obesity, diabetes and a host of other health problems in cats and dogs. Conventional dry dog feed have a very high carbohydrate content, with most foods exceeding 40-50% in total carbohydrate content.
Almost half of typical McKibble is nonessential, simple sugars! This important fact is often lost on consumers as pet feed makers are not required to claim carbohydrate content on their packages.
The Association of American Feed Control Officials’ (AAFCO) nutrient profiles show that carbohydrates are not essential for dogs and cats, and that no minimum level of carbohydrate is needed in their diets. According to Dr. David S. Kronfeld, carbohydrates need not be supplied to adult dogs, even those working hard as the liver is easily able to synthesize sufficient glucose (from protein and fats)17.
References and Research
- 1.Hall JA, Vondran JC, Vanchina MA, Jewell DE. When fed foods with similar palatability, healthy adult dogs and cats choose different macronutrient compositions. J Exp Biol. Published online May 17, 2018:jeb173450. doi:10.1242/jeb.173450
- 2.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. J Anim Physiol Anim Nutr. Published online October 12, 2017:568-575. doi:10.1111/jpn.12794
- 3.Marshall DA, Blumer L, Moulton DG (deceased). Odor detection curves for n-pentanoic acid in dogs and humans. Chem Senses. Published online 1981:445-453. doi:10.1093/chemse/6.4.445
- 4.Marshall DA, Moulton DG deceased. Olfactory sensitivity to α-ionone in humans and dogs. Chem Senses. Published online 1981:53-61. doi:10.1093/chemse/6.1.53
- 5.Jenkins EK, DeChant MT, Perry EB. When the Nose Doesn’t Know: Canine Olfactory Function Associated With Health, Management, and Potential Links to Microbiota. Front Vet Sci. Published online March 29, 2018. doi:10.3389/fvets.2018.00056
- 7.Meyers H. Are Dogs Color Blind? Side-by-Side Views. American Kennel Club. Published 2019. https://www.akc.org/expert-advice/health/are-dogs-color-blind/
- 8.Lei W, Ravoninjohary A, Li X, et al. Functional Analyses of Bitter Taste Receptors in Domestic Cats (Felis catus). Behrens M, ed. PLoS ONE. Published online October 21, 2015:e0139670. doi:10.1371/journal.pone.0139670
- 11.Lenox CE. Role of Dietary Fatty Acids in Dogs & Cats. Today’s Veterinary Practice. https://todaysveterinarypractice.com/role-of-dietary-fatty-acids-in-dogs-cats/
- 12.Hill AS, Werner JA, Rogers QR, O’Neill SL, Christopher MM. Lipoic acid is 10 times more toxic in cats than reported in humans, dogs or rats. J Anim Physiol Anim Nutr. Published online April 2004:150-156. doi:10.1111/j.1439-0396.2003.00472.x
- 13.Becker K. Fermented Vegetables: Finicky Pets Might Not Like This Superfood, But It’s a Potent Cancer Fighter. Healthy Pets Mercola. Published 2014. https://healthypets.mercola.com/sites/healthypets/archive/2014/08/31/pet-fermented-vegetables.aspx
- 14.Fermented Foods for Dogs and Cats. Dr. Heartway. Published 2014. http://www.drperrinheartway.com/2014/11/11/fermented-foods-for-dogs-and-cats/
- 15.Bell V, Ferrão J, Pimentel L, Pintado M, Fernandes T. One Health, Fermented Foods, and Gut Microbiota. Foods. 2018;7(12). doi:10.3390/foods7120195
- 17.Kronfeld DS, Hammel EP, Ramberg CF Jr, Dunlap HL Jr. Hematological and metabolic responses to training in racing sled dogs fed diets containing medium, low, or zero carbohydrate. The American Journal of Clinical Nutrition. Published online March 1, 1977:419-430. doi:10.1093/ajcn/30.3.419