Pet Food In The Convenience Era

An overview of small animal nutrition trends with particular reference to the argument against cooked commercial pet foods versus raw food diets.

The History of small animal nutrition

The earliest records of the canine and feline families dates back to 38 million years BC. Mankind has been living with the domesticated dog ( Canis familiaris ) since we were cave dwellers, as far back as 8500 years BC. We can therefore safely assume that for the first 37+ million years, ancestral dogs and cats ate a natural raw diet, much the same as their wild contemporary relatives do today. For the next 10,000 years, history tells us that dogs and cats were kept not only as companions, but for their abilities as hunters…feeding on natural prey was part of their role in pest control for the community. They were not kept in yards, but were free to hunt and scavenge their meals, being lucky to get the occasional cooked food scraps. It was not until  the 20th Century that the first active encouragement to cook foods for dogs and cats occurred, driven by fears of disease and parasite transmission. Finally, in 1965, Uncle Ben’s of Australia  released this countries first commercial cooked dog and cat foods. It may come as a surprise to some that the very concept of a cooked commercial dog and cat food did not come from any veterinary channel at all, but was developed and marketed initially overseas ( the Mars Co. in the U.K., Uncle Bens in the U.S.A.) by companies that already specialised in packaged, processed food products. They did not set out to produce foods that were superior to the raw food diets currently being fed, but to produce a “convenience” product. They set out to tap into what is now in this country alone, a multibillion dollar market, by producing a packaged, storable, fast food for animals.( We must remember that in the late 60’s and 70’s, pre-packaged and tinned food products were very popular , they were seen to be “modern” and so “convenient”. Our general knowledge of the poor health aspects of people eating like this took another 15-20 years to come to light). It was not until it became apparent that the cooking process was destroying essential vitamins and creating deficiencies that the veterinary profession became actively involved the production of these commercial pet foods. Accompanying the release of Pal and Whiskas in this country was what has been described as “the greatest marketing campaign until Mc Donalds”. The advertising  was so successful that in under 10 years, over 60 % of the pet owning population were using commercial pet foods in some form. The marketing exercise, which includes such familiar lines as “top breeders recommend Pal, vets recommend Pal, and I wouldn’t feed my dog anything else …..” is still used in teaching institutions as a great example of the marketing machine at work.

The facts against cooked food

Omega 3 essential fatty acid deficiency

Omega 3 and Omega 6 essential fatty acids form an integral part of the phospholipid bilayer of the cell membrane and determine the physical and functional properties of the cell membrane and hence have important implications for cell function with regard to integrity, growth, inflammation and immune function. With regard to their role in the inflammatory cascade, they are the precursors of the eicosanoids, which include the prostaglandins, thromboxanes, leukotrienes and prostacyclins. The Omega 6 oxygenation pathway ( linoleic acid to arachidonic acid) results in the production of the pro inflammatory protaglandin 2 series, and the pro aggregatory, immunoreactive leukotriene 4 series. Conversely, the Omega 3 oxygenation pathway ( alpha-linolenic acid to eicosapentanoic acid) results in the production of the anti inflammatory prostaglandin 3 series, and the anti aggregatory, non immunoreactive leukotriene 5 series. The Omega 3 EFA’s are very volatile, being easily destroyed by heat over 40’C (cooking), light, and oxygenation, and as such will turn “rancid” rapidly.( In fact they have been shown to become carcinogenic if heated over 100’C). As a result they have been selectively removed from most commercial food products and replaced with oils that are naturally high in Omega 6, which are much more stable and will greatly prolong the shelf life of these products. The commonly used commercial oils like safflower and sunflower oils are naturally high in omega 6, and very low in omega 3. Compounding this is the fact that as part of the processing of these oils, they are super heat treated and bleached to produce the clean, clear oils that we see on the supermarket shelf (which removes any trace of Omega 3 EFA and again extends shelf life). The very same situation exists in commercial cooked pet foods. The result of this selective removal and processing system has been a massive imbalance of Omega 3 : Omega 6 ratio in processed foods, falling from 1 : 5 down to 1 : 15-20. Because Omega 3 and Omega 6 EFA’s compete for enzymatic oxygenation, the result is a massive increase in available linoleic and arachidonic acids, and the resultant pro inflammatory prostaglandins and leukotienes. Which in turn primes the leucocytes, platelets and endothelial cells of the immune system towards excessive immunoreactivity. To the dog or cat this translates as excessive reaction to normal or mild antigenic stimulii, leading to flea bite hypersensitivity, atopic dermatitis, contact allergy, and to over reaction to joint wear and tear resulting in chronic osteoarthritis. Human studies have linked Omega 3 deficiency to a number of common degenerative diseases including inflammatory bowel disease, glomerulonephritis and cancer, and is a primary factor in the massive rise in heart disease and cholesterol problems in western culture. The good news is that deficiency can be easily reversed after 3-4 weeks of daily Omega 3 supplementation. Omega 3 supplements include cold pressed flax seed oil or canola oil, and raw marine oils like cod liver oil.

Digestibility / Denatured protein

A study was performed on laboratory rats fed on two different diets. One group were fed on raw meats, vegetables, nuts and whole grains, the other group were fed the same diet cooked. On post mortem, the group fed on the cooked diet showed a 30% increase in gross pancreatic weight. This suggests that the cooked food requires greater enzymatic production to enable digestion and subsequent absorption. Another more recent discovery was the fact that the syndrome of ” digestive or post prandial leucocytosis “, an observed consistent rise in white cell count after the consumption of food, which was considered normal, does not occur after the consumption of totally raw diets. This strongly points to a growing body of evidence and medical research that connects absorption of denatured protein molecules from the bowel, to the formation of circulating immune complexes that can lodge or are sequestered in body tissues causing diseases like asthma, arthritis, inflammatory bowel disease, autoimmune glomerulonephritis, and a myriad of other auto immune linked degenerative diseases. If cooking denatures a “normally recognisable” food protein only slightly, such that in the bowel it is still recognised to be absorbed, but enough that it is recognised by some fraction of the circulating immune system as part foreign, then it is quite possible to form these immune complexes. If perhaps the immune recognition is only weak, but enough to prevent metabolisation of the complex, it is also possible that these complexes may be stored by the body in different tissues, where they could theoretically cause an ongoing chronic immune response. If this tissue was kidney, it would cause glomerulonephritis, if joint tissue, it would cause arthritis, etc,etc…in animals ,if they lodged in the skin they could cause chronic dermatitis, in the gums, chronic gingivitis… Very recently a report on television stated that medical research into a 40% increase in infant diabetes mellitus, had found a connection to the consumption of denatured dairy protein (infant pasteurised milk formula). Gut passage time for ingesta on cooked diets is also markedly increased compared to the equivalent raw food.


It is a well-known fact that cooking denatures proteins, and as such, destroys many natural vitamins in foods….which are necessarily added back to the cooked product before the final product is packaged (at least in most pet foods they are, which is more than most human processed foods can say). But this leaves the question of what else is destroyed that we are not fully aware of ? Pottenger’s cat experiments (see later) clearly demonstrate the full detrimental effect of cooking on foods and their subsequent metabolism. They clearly demonstrate the effects of vitamin deficiency, but this alone cannot explain the results of his study. It is certainly true that intracellular enzymes are destroyed by cooking..which has been the longest method of preserving known to man. But by destroying the natural autolytic cell enzymes (capthesin), a much greater demand on the body’s own digestive enzyme cascade is required to digest and subsequently absorb nutrient. It is a well-documented fact that living tissue has enough intracellular enzymes to completely auto digest to the very last single molecule. An easy test is to compare the end result of a raw steak cf. a cooked steak, left to sit on a plate for a couple of weeks at room temperature. I will discuss the effect of intracellular enzymes in more detail later. One of the other examples of altered bioavailability is the effect of heating or denaturing of milk proteins. Pottenger’s study demonstrated a dramatic loss of calcium density in the bones over the 9 generation study. Calcium density dropped from 17 % in the first generation, to only 4 % in the final generation, compared to no change in the control (raw food) group. Given that the only difference in the diets was cooking, this clearly demonstrates an unknown mechanism that is effecting either calcium absorption or metabolism as a result of heat treatment. Other studies on the effects of pasteurising milk have shown a link to chronic osteoarthritis, allergy formation, and more recently to infant diabetes. Again, how many of you would be surprised to know that pasteurised milk powder is one of the most common sources of protein used in commercial pet food manufacturing.

A great example of how our “scientific” minds can alter our perception can be seen by the massive increase in advertising of “nutritional breakdowns”. Figures in black and white often look impressive, but they take no account of the bioavailability of the nutrients listed. The very testing for these compounds involves incinerating samples and reading ash contents. You may have noticed that McDonalds now have a nutritional display sheet at every store..looks good on paper !! The very fact that there is medical research evidence that shows marked increases in physical strength and stamina on raw food diets compared with regular cooked diets ( these trials were performed in the army) strongly indicates that there is more damage occurring during cooking than simple vitamin losses. There are also many other factors in commercial cooked pet foods that are of concern, including preservatives, artificial colours and flavour enhancers, antioxidants, and the use of “render” as a base material in some less commercial food lines, but these issues are not within the scope of this discussion. See following the results of some studies on raw food nutrition, and on the effects of cooking. Also a brief overview of Pottenger’s cat study, although quite an old study, it still brings to light in a dramatic way the full effects of cooking on a basic natural, otherwise healthy, diet. It surely leaves the question in your mind, why bother cooking for animals at all ??? And it raises the somewhat insidious notion that the damage occurring from cooked food consumption may have a generationally compounding effect.

The facts against cooked food


40 million years of evolution on raw food diets compared to thirty odd years on our cooked formulas. The whole intestinal tract of cats and dogs, starting from the mouth and teeth to the anus, the pancreas, liver and other digestive tissues and enzymes have all been finely tuned over 40 million years to digest and absorb raw meats and foods. Even the most basic scientific mind can see that this alone clearly suggests that these animals will surely perform better on a raw diet. There are few other examples, except for mankind itself, where we can see the effects of such a radical dietary manipulation after so many years on a natural diet. It should come as no surprise that the cats and dogs in our present care are beginning to suffer from the same degenerative diseases that our own population suffer from. Dermatitis, arthritis, gingivitis and dental caries, renal failure, diabetes, pancreatitis, inflammatory bowel disease, FIV, leukaemia, and the myriad of autoimmune and neoplastic diseases that make up the long list of degenerative diseases which are now simply “accepted” as part of growing old…are actually the result of years of nutritional abuse. This fact has been accepted by the medical profession, who are now at least in part, promoting increased consumption of fresh raw foods as part of a balanced diet. What are we doing in the veterinary profession ? How many vets actually recommend some portion of the animals diet be raw (apart from the odd bone for dental care)? Or are we all convinced that today’s dogs and cats will be far better off and much healthier if they eat Eukanuba or Iams every day of their life ?

In the few animal species where mankind has interfered with the natural diet of animals (eg.chickens, pigs, feedlot cattle etc), we consistently see the emergence of new diseases and generalised poor health…even to the point where we must add constant antibiotics to the feed so that they don’t all die from common bacterial diseases. Even personality is changed, with increased aggression and cannibalism occurring (obviously environment has a lot to do with this also).


All raw foods contain cellular enzymes capable of complete auto digestion of cellular structure, and release of cellular content, down to the single molecular level. This process naturally occurs within the stomach and intestines of an animal when it feeds on raw prey, accelerated by the core temperature within the bowel, and by the addition of extracellular digestive enzymes from the pancreas and intestinal wall, and also by the intestinal microbial flora. This process enables the release of intracellular nutritional content in its most simple and absorbable natural state. When foods are cooked, the natural intracellular enzymes are destroyed (denatured), placing all the digestive load on the animals own body (hence the demonstrated pancreatic hypertrophy). Given that these pancreatic and intestinal enzymes have evolved to digest raw foods, it is conceivable that they are not able to appropriately or completely digest the cooked, denatured proteins that they now encounter, leaving a percentage of the potentially available nutritional content indigestible or unabsorbable ( relates to the concept of bioavailability vs. nutritional content ). The other very important factor relating to enzymes is the research and information coming from the U.S.A. regarding enzyme deficiency. This research is showing that an animals body has a limited lifetime reserve of digestive enzymes, and that deficiency of these enzymes, which occurs in animals (people) who eat a majority of cooked foods which requires much greater enzyme output, can have more far reaching effects than purely on digestion alone. Enzyme deficiency has been linked to allergies and a number of other degenerative conditions. This deficiency seems to occur about two thirds into the animals natural lifespan. This explains why dogs and cats on commercial foods will often perform quite well until around 6-8 years of age, and then the incidence of skin disease, dental problems, arthritis, kidney failure and the many other common “old age” problems begins to rise dramatically. This has been evidenced by trials using enzyme supplements by Dr Wendell Bellfield DVM. He demonstrated a marked improvement in both appearance, vigour, and general health in older animals when placed on Aspergillus spp. digestive enzyme supplements ( found to be stable in the acidic stomach environment compared to many commonly used animal derived supplements).

Natural balance

Even the most simply put together raw food diet containing appropriate ratios of raw meats, carbohydrates and vegetables requires few if any additives to provide adequate and balanced levels of essential fatty acids, vitamins, minerals and trace elements. Deficiencies do not occur readily if just a little educated thought goes into preparing a raw food diet for dogs and cats. I find it disturbing that small animal nutrition receives so little attention at the educational level. In final year we were given all of 7-8 lectures on dog and cat nutrition, most of the notes and information supplied directly from Uncle Bens nutrition handouts. Only one lecture actually dealt with unprepared diets and nutritional aspects of the different food groups. This compares rather poorly with the years of study and subjects relating to pasture growth and large animal nutrition that we deal with…naturally this tends to reflect the history of the relative economic importance of large animal nutrition, and the degree to which we have been called upon to act as nutritional advisors in the veterinary field. This situation has changed quite dramatically over the past twenty years, and small animals now represent a very significant percentage of veterinary work, and small animal nutrition has become a multibillion dollar industry in this country alone. We are now regularly called upon to discuss dog and cat nutrition in the practice situation , or to recommend a brand of pet food. It would seem that we have been happy to regurgitate the information fed to us by the commercial pet food companies, both in university and in practice, and that there is a strong financial and ‘credibility’ aspect involved in keeping the profession continuing to support commercial pet food.

Physical aspects

Longevity is a factor consistently discussed with regard to nutrition. There is masses of research results that show that humans live longer when they eat a raw food diet. A simple in clinic test which never fails to arouse ones credibility to this fact is to make a note to ask the owners of the next ten or so , what one would term ” older than average ” patients, what type of food they mainly feed their pet. I find on average approximately 80 % of dogs over 16 years old, cats over 17-18 years old, have been fed a majority of raw food in their diet.. But don’t take my word for it! Lions kept in captivity, away from all the rigours of real life, live over 30 years (compared to 15-20 in the wild). Interestingly, zoos across the world have never adopted the practice of cooking meat for the carnivores in captivity…they are still fed as their wild counterparts are, all raw. I wonder why that is?

Dental status has always been a topical issue with regard to commercial cooked pet foods. There is little doubt that animals on raw food diets have healthier teeth and gums, even at very old ages. Studies performed on rats, and results from Pottengers study, show a weakening of bones and teeth, and increased incidence of dental caries and gingivitis, in animals on cooked food diets compared to animals on a raw food diet. This may be related to alteration of normal calcium absorption and metabolism, or connected to denatured dairy protein intake, or just because cooked foods are more adherent to dental surfaces and result in tartar accumulation more readily.

Fertility has been demonstrated to decline with increasing consumption of cooked foods. In humans, the male sperm count in western societies on typical western diets has been declining alarmingly every year. In Pottengers study, the cooked food group became completely infertile. How much of this can be attributed to cooking, and how much to vitamin deficiency remains unclear. In one study, foetal flexibility was shown to be greatly increased on a raw food diet, resulting in much shorter labour times and far fewer obstetrical complications.

Faecal matter produced from dogs and cats on cooked foods is consistently poorly formed, leading to improper anal gland function. They are more offensive smelling, are slower to break down in the environment, and were demonstrated not to encourage plant growth in comparison to faeces from the raw fed cats which actively encouraged plant growth. In Summary Common sense and evolutionary history tells us that a raw diet for dogs and cats must ultimately promote better long term and day to day health than the cooked, preserved, flavour enhanced fast food products that western society has created for their canine and feline companions. To feed our need for convenience, we have adopted this feeding strategy, forgetting some of the most fundamental concepts of nutrition. To not only convince ourselves, but to actively promote these products over a natural raw diet will undoubtedly one day be the shame of the veterinary profession. Mankind has a bad track record of interfering with mother nature. We are only just beginning to feel the repercussions of our ancestors’ environmental abuse. The general health of the western world is deteriorating rapidly as the food we eat and the environment we live and breathe in becomes more toxic and artificial. Degenerative diseases that are increasing at alarming rates ( arthritis, allergies, asthma, heart disease, Alzheimer’s, cancer…) have become accepted parts of the ageing process. And with domestic dogs and cats, after 38 million years on raw food, we have just decided to completely change their diet to resemble our own cooked food, complete with all its preservatives, flavours, and colours. Now that our animal companions are developing all the same degenerative diseases, we are still , as the animal health professionals, not uniformly confronting the fact that it is time to re think our position on small animal nutrition, and begin to at least recommend that some portion of the diet should be raw.

Dr Bruce Syme BVSc (Hons), Founder of Vets All Natural.

Dr Bruce Syme is a practicing vet and expert in natural pet nutrition, has spoken at the Australian Veterinary Association Annual Conference, and provides regular comment on TV and Radio.

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Disclaimer: The entire contents of this article are based upon the opinions of Dr. Bruce Syme, unless otherwise noted. The information is not intended as medical advice, it simply shares the knowledge and information from the research and experience of Dr. Bruce and his community. Pet health care decisions should be based upon your research and in partnership with a qualified pet health care professional.
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