Feline Diabetes and Obesity:
The Preventable Epidemics
© 2004 Elizabeth Hodgkins DVM, Esq.
Today, the cat is the favorite housepet in the United States,at least if your definition of “favorite” is “most numerous.” The cat has outnumbered the dog, thepreviously “most numerous” pet species, for a decade or more and this trendshows no signs of reversing itself anytime soon. Those of us involved in any of the pet careindustries or professions know very well that we are seeing more and morewell-cared-for felines, belonging to people and families that are intenselybonded to their kitty family members. Men, as well as women, in all socioeconomic strata, are attached totheir pet cats in a way that I could never have anticipated in 1977 when Igraduated from veterinary school. Inshort, the cat has become not only legitimate as a pet underfoot, but also afocus of attachment and affection for humans who are often willing to doanything and everything necessary to provide their felines long, healthy, andhappy lives.
This desireand willingness to care for a pet cat’s every need has resulted in somesignificant improvements in health and longevity for felines today. For example, the increasingly common indoorexistence enjoyed by cats has greatly reduced the incidence of most infectiousdiseases within cat populations and has markedly curtailed death and injury tocats from automobile accidents, attacks from dogs or wildlife, or other sourcesof trauma. More routine spaying andneutering of household pet cats has positively affected the number of abandonedand neglected cats put to sleep in shelters. Unfortunately, while so much is better for cats today, this species hasnonetheless paid a price for the heightened level of care it receives from themillions of devoted cat owners in the country. That price is loss of health associated with poor nutrition in the formof commercial dry cat food diets.
First, some background on the evolution of the cat forcontext. Today’s domestic cat evolved from one or more small wild catspecies in Africa and southern Europe. The environment in which these progenitor cats developedwas vegetation sparse and small-animal-prey rich, causing this top-predatormammal to become dependant on meat, and meat’s primary energy nutrients,protein and fat, for sustenance. Over time, some of the pathways forcarbohydrate metabolism that were developing to a high degree in herbivorousand omnivorous species in more carbohydrate-rich environments were discarded bythe primitive cat. In fact, eventually this species so drasticallyrearranged its processes for dietary energy extraction that its metabolicsystems began to use protein for energy at a constant, almost invariable rate,without the switches for up- and down- regulation of that protein “burn” (gluconeogenesis from amino acids) that is active inomnivores and herbivores. That is, the cat will use dietary protein for routineenergy production at a high level EVEN in situations where dietary protein isvery limited. Because of theseevolutionary “choices” made long ago, the cat rapidly begins to consume itsstructural proteins for energy during starvation or protein deprivation of anyother kind (e.g., protein-restricted diets). In short, the cat is a “carbohydrate cripple” with a huge proteindependency!
Given theforgoing, it is not at all surprising that we now find many of our felinepatients fat, sluggish, and eventually, diabetic. For all of our good intentions in bringingthe cat into our homes as a pampered pet, we have done the species a tremendousdisservice in providing its members a diet far more appropriate for a cow in afeedlot than an obligatory carnivore. Because of the food technology of dry food production, dry cat foods areloaded with carbohydrate from cereal. This carbohydrate is absolutely required in the extrusion process; drypet foods are essentially breakfast cereal for pets with a little added meatmeal for palatability. Further, because this cereal undergoes processing athigh heat and pressure during extrusion, it becomes pre-digested and enters thepet’s bloodstream essentially as “sugar.” Nothing in the cat’s evolutionary development could possibly have preparedit for a steady diet of this sugar laden “junk food.”
Not allcereals are created equal, of course. Some have much higher glycemic indicesthan others, meaning they cause a greater rise in blood glucose when consumedand digested. Perhaps the most offensiveof all cereals used in pet foods is corn, (from which corn syrup is derived,giving a good idea of how much sugar corn actually contains). Because it is plentiful and cheap in thiscountry, corn is one of the favorite dry pet food cereals used by theindustry. Sadly, even the mostexpensive, so-called premium dry pet foods contain high amounts of thisingredient.
Anadditional consideration is the cat’s unique system of satiety signals fromfood. Logically, because the cat evolvedin an environment rich in protein and fat, but deficient in carbohydrate,consumption of fat and protein evolved as the signal to the cat that it couldcease intake. Consumption of carbohydrate, however, has a minimal effect onintake in the cat even as energy requirements are met and exceeded with thisnutrient. Thus, not only is the catrelatively incapable of handling repetitive substantial carbohydrate loads ofthe kind represented by dry cat food, it is also unable to respondappropriately to that consumption with appetite satisfaction. The end result is cats that overeat,constantly flood their systems with glucose overloads, spiking repeated surgesof insulin from their limited carnivore’s pancreatic reserve, and becomeobese. For a large number of cats, theirmetabolic systems eventually become overwhelmed by this unphysiologicchain of events and its unremitting stress on the pancreas, resulting indiabetes.
Assumingthe preceding description of the present state of nutrition for pet cats iscorrect, how could this possibly be? How and why would a multi-billion dollarUS pet food industry “conspire” to foist essentially “poisonous” food off oncat owners, often at very high prices and at exclusive, inconvenient outletssuch as veterinary facilities and pet stores? To begin to answer that question, we must go back, once again, intohistory.
At the middle of the last century,there were no commercial pet food products to speak of. Pet animals were fed fromthe table or the local butcher’s discards. However, during the 50s and 60s, themarket for convenient dog foods began to grow. Companies like Purina Mills, a cereal grain processing company,recognized this emerging market and began to make baked biscuits for dogs. Over time, Purina and other cereal-processingcompanies began producing kibbled dog food with the same technology used inmaking breakfast cereal for humans. At the same time, Alpo began to candiscarded meat scraps and/or condemned meat for dogs. Because of their convenience andaffordability, both types of food had appeal for dog owners and growing salesof these products encouraged additional output by these and a few smallerprocessors.
Unfortunately,these early attempts to produce dog foods were driven entirely by a desire tofind profitable uses for excess commodities, specifically corn and other grainsas well as meat unfit for or unused for human consumption, rather than a desireto provide genuinely health-promoting foods for pet dogs. Because Alpo’s canned meat was completely unsupplemented for vitamin/mineral balance, it causedserious deficiency diseases in dogs that consumed it as most or all of theirdiet. As a result of the resultingscandal, the company decided to add a general vitamin/mineral supplement to itscanned meat, and all other processors followed suit. Purina and other companies making kibbled dogfood also began adding vitamins and minerals to their kibble, which was marketedas an adjunct to fresh meat or canned meat foods for completeness.
Asdecades passed, many dog owners began to favor kibbled dog food because of itseconomy, convenience and keeping qualities. Pet food-producing companies responded to this market demand by addingprotein ingredients to their kibble in an attempt to produce a more completedry food. Finally, the AmericanAssociation of Feed Control Officials (AAFCO), a regulatory body that thensupervised the quality and safety of livestock feeds, agreed to acceptresponsibility for supervising pet foods as well. For the first several years of this oversightresponsibility, AAFCO reviewed available literature and compiled a list ofminimum and maximum levels of key nutrients that must be present in a dog foodlabeled as complete and balanced. No actual feeding studies were required, butrandom samples of a company’s foods (this requirement applied to canned as wellas dry foods) were expected to meet the established minimums and maximums. Eventhough this was an important improvement in the assurance of the quality ofthese foods, their ingredient content continued, and continues to this day, tobe ingredient-cost and ingredient-availability driven. Meeting nutrient requirements is achieved byadding supplements when the ingredient mix that is most cost effective does notprovide the right balance alone.
Into thisenvironment enters the cat as an increasingly “kept” pet for which owners beganto clamor for complete and balanced commercial foods as well. While it was understood by manufacturers thatthe cat had some unique nutritional requirements as a result of its status asan obligatory carnivore (e.g. the need for preformed vitamin A because the catcannot synthesize this vitamin from dietary beta-carotene as humans and dogscan, the need for high levels of arginine and taurine because of high use and limited internal syntheticcapabilities for these amino acids, the need for dietary arachidonicacid because of an inability to produce this fatty acid internally, etc.),these requirements were somewhat cavalierly addressed by the pet foodcompanies, as we will explore shortly in the matter of the devastating taurine-deficiency problem with most canned cat foods thatarose in the late 1980s. Certainly, thecat’s completely unique metabolic machinery designed for high production of energyfrom protein and near exclusion of carbohydrate as an energy substrate wasentirely ignored. Essentially, as dry cat foods began to emerge in response tocat-owner demand, they were little more than dry dog foods, processed intosmaller, cat-sized kibble, with a slightly different vitamin/mineral mix added.
In fact,both canned and dry cat foods are the product of marketing and food technologyconsiderations, not the science of feline nutrition. Witness the fact that canned and dry forms ofthe exact same formula of any brand with corresponding forms, have entirelydifferent macronutrient profiles. Cannedproduct has relatively high protein (usually about 40-55% on a dry matter basis), moderate fat (usually 25-35% DMB) and low carbohydrate(usually about 2-8% DMB). Dry foods bear absolutely no nutritional resemblanceto their corresponding canned version. A dry food will typically have about20-33% protein, 10-25% fat, and 20-50% carbohydrate! In addition, dry foodsoften have relatively high fiber content (5-8%) while canned foods, unless theyhave fiber deliberately added as a separate ingredient, have negligiblefiber. Why would different physicalforms of the exact same formula, for the exact same “life stage,” have suchvery different macronutrient contents? Do kittens and cats have different needsdepending on whether they are eating canned or dry? The short answer is no, ofcourse not. The cat has the exact same macronutientneeds whatever form of food it consumes, so why the great difference in theseformulas?
Thedemands of food technology in the production a dry kibble using the process ofextrusion, (same as breakfast cereal for humans) dictate the macronutrientprofile of dry pet foods. Extrusion isthe expansion and “popping” of kibbles through a high heat, high pressureprocess that will not occur without substantial starch content in the slurrythat is fed into the extruder. A cannedfood formula, sent through an extruder, will end up a damp puddle the end ofthe machine, rather than fluffy, air filled kibbles ready for drying. So, tons of corn, rice, wheat, oats, barleyand other grains (the less expensive the better, of course) are added to themeat meal and low volume ingredients that comprise dry pet foods because the product form will notmaterialize otherwise.
Further,dried kibble is almost completely unpalatable for the typical cat. This is not surprising; one would expect thatthis species would recognize high cereal foods as “not food.” In response, an entire industry has grown up,right alongside the expansion of the dry dog and cat food industry, to produceand provide potent palatability enhancers for coating pet food, especially cat food. These palatability enhancers may be acidifiedyeast (cats like the taste and/or mouth feel of acid substances), but morecommonly are meat “digests.” Digests areproduced when food animal entrails are fermented into a sprayableliquid mixture with acid added and then sprayed onto the outside of the dry catfood kibble. Few pet owners, includingthose adamantly opposed to the feeding of raw foods to their pets, would be socomplacent about commercial dry pet foods if they witnessed the production andapplication of this ingredient. Thus,cats are essentially “tricked” into the consumption of a food they would notordinarily consume, through the application of tasty outer coatings. One is reminded of the application of candycoatings on the outside of children’s breakfast cereal to enhance theconsumption of relatively low nutritional-value breakfast foods.
Now,contrast the formulation and production of dry cat foods with the formulationand production of canned or “wet foods.” The starch requirement that extrusion places upon dry pet foodproduction is absent in wet foods. Pates, even chunked, sliced, or grilledmeats, go perfectly well into a sealed can that is then sterilized in ahigh-heat retort. Happily, high meatformulas are highly palatable for cats, who recognize such ingredients asappropriate foods for their nutritional needs, which they usually eat happilywithout additional palatability enhancers added. Thus, canned foods have macronutrientprofiles that are high protein, moderate fat and low carbohydrate, because thisis the nutrient profile of meat-based food that will not be extruded and willnot require palatability enhancers. This is quite different from themacronutrient profile of dry foods, which are slave to the food technology ofextrusion and the resulting need for intense palatability enhancement with“sugar coatings” of fermented digest post production. The ingredients and macronutrients of thedifferent forms of cat food are dictated by the requirements of food technology,not the science of feline nutrition. To this day, not one person at any of themajor or minor pet food companies has ever questioned the wisdom of feedingdiets that are 30-50% pre-digested carbohydrate to an obligatory carnivore, andour cats have paid the price for that negligence.
Many petowners believe that commercial pet foods are safe and efficacious to feed totheir pets because they have been “feeding trial tested” and shown to becomplete and balanced by this method. The AAFCO statement on many pet foods bears testament to the fact thatthe contents of the can or bag have undergone some kind of feeding trial thatguarantees that the food in the container is good for your pet. This statementis extremely misunderstood by most pet owners and misleads them into believingthat only good can come of feeding the product on which this statementappears. To illustrate this problem,let’s go back in recent history.
Inapproximately 1988, a young cardiology resident at the University of California at Davis by the name of Dr. Paul Pionnoticed something rather interesting. One of his feline patients, a cat he wastreating for congestive cardiomyopathy, had anextremely low serum taurine level. Taurine is an essential amino acid in the cat (meaning itcannot be synthesized in sufficient quantities by the cat to meet its ongoingneeds and must be supplied in the diet), known to be required for proper eyeand cardiac function in this and many other species. Dr. Pion’s patientwas fed an exclusive diet of a “high quality” premium commercial canned catfood, which should have supplied all of the taurinethis cat required. After all, the food was “feeding trial tested” and shown tobe complete and balanced for all life stages in these feeding trials. Surelythis cat’s heart disease was not due to consumption of a taurine-deficientdiet?
Over themonths following his initial observation, Dr. Pionsupplemented his original patient’s diet with taurineand began to investigate other clinical cases of feline congestive cardiomyopathy. Tohis amazement, Dr. Pion discovered that virtually allof the cases he studied had low taurine levels intheir bloodstream, and many of them improved dramatically, even returned tonormal, when supplemented with taurine in addition totheir regular diets, which were always canned commercial pet foods. Most ofthese cats were fed diets that had been “feeding-trial-tested” and shown to becomplete and balanced for the appropriate life stage by this method.How could such diets be responsible for a fatal disease condition in cats? Howcould foods produced by the “best” pet food manufacturers and tested accordingto the most stringent AAFO guidelines be the direct cause of such pathologicdeficiency in pet cats?
Theanswer, although not immediately evident, became clear over the first fewmonths of Dr. Pion’s investigation. The taurine in theimplicated diets, often tested in the laboratory as adequate for the health ofcats, was somehow not available to those cats when consumed in thosediets. The processing of the canned formulationsin the retort somehow “inactivated” the taurinecontained in the foods so that it tested as adequate using laboratory methods,but in the “ultimate laboratory,” the cat itself, the dietary taurine was not properly recognized and utilized. If this were the case, however, why didn’tthe feeding trials of these foods disclose this terrible flaw? Why? Because thevaunted feeding trials of which the companies and AAFCO are so proud are ofsuch limited duration, usually no longer than 6 months, that only severeinadequacies and acute toxicities would ever be disclosed through them.
Further,had cats on a six-month feeding trial of a taurine-deficientdiet developed congestive cardiomyopathy during thetest period, it is extremely unlikely, prior to the problem discovered by Dr. Pion, that anyone would have recognized the condition asdiet-related. Much more likely, any cat thatdeveloped cardiomyopathy during the test would havebeen diagnosed as having a congenital/hereditary defect and removed from thetest cohort. Most cats would not become sufficiently deficient to develop overtclinical signs during the feeding trial. Thus, deficient diets were produced,feeding-trial-tested, and marketed for many years, causing the deaths of manycats, before a fortuitous turn of events and the keen observations of a youngveterinarian allowed the problem to be identified and corrected. The pet food companies and their “rigoroustesting for safety and efficacy” allowed the development of a fatal disease inthousands of cats, and that gad to be discovered and corrected through theefforts of an outsider who was not even a nutritionist. The “scientific teams” within the implicatedcompanies themselves were stunned by the discovery.
Thepresently prevalent nutritional diseases of obesity and diabetesshare stunning similarities with the taurine-deficiencydisease of feline congestive cardiomyopathy. True enough, the disease associated withdietary taurine was a disease of nutrient deficiency,while diabetes and obesity in cats are diseases of nutrient excess. Both cardiomyopathy of taurine-deficiencyand obesity/diabetes of carbohydrate excess are diseases of insidious onsetthat can be attributed by non-astute or biased observers to chance or heredity. All are diseases that existed, and in thecase of diabetes/obesity, continue to exist, despite assurances fromnutritionists at major pet food companies and AAFCO that the diets causing themwere, or still are, complete and balanced and perfectly healthful for cats. Both taurine-deficiency-cardiomyopathyand carbohydrate-excess-obesity/diabetes were made possible by inadequatelaboratory testing of pet foods endorsed widely by pet care professionals, alongwith the pet food industry’s failure to consider the effects of ingredientprocessing on ingredient nutritional value. Further, these diseases, and perhaps others yet to be uncovered in thefuture, are the result of an unfathomable failure by those most knowledgeableabout the peculiar metabolic machinery and nutritional needs of the cat toproperly consider those factors. By andlarge, the pet food industry has treated the cat like a “small dog,” because itwas expedient and seemed so harmless for so long.
Pleasenote that not all cats that consume substantial dry cat food become obese, ordevelop diabetes, or idiopathic cystitis, at least not during the length oftheir lives, whatever that might be. Similarly, not all cats that consumed taurine-deficientcanned foods in the 1980s developed congestive cardiomyopathy,at least not before the link to canned foods was discovered and corrected. We know that as harmful as cigarette smokingclearly is for human beings, not every person that smokes cigarettes willdevelop cancer, or emphysema, or heart disease, at least not before some othercause of death intervenes. These factsdo not diminish in the slightest the unavoidable conclusions we have come toabout the harmfulness of cigarette smoking, and the dangerousness ofnutritionally deficient or excessive diets. Some people and animals are more resistant to environmental harms thanothers, but it is virtually impossible to tell which individuals these arebefore it is too late. Therefore, everyindividual in every susceptible population must be considered at risk.
What isto be done about the present rampant feeding of carbohydrate-laden dry catfoods? Shouldn’t those who are gainingfinancially from the present high level of commercial pet food demand and whohave the expertise to formulate and produce truly healthful feline diets, doso? Of course they should. The pet food companies that have setthemselves up as the pet nutritional experts among us have the obligation todeliver the safety and efficacy they have been claiming for so long. Unfortunately, without intense consumerpressure, that is highly unlikely to happen. All pet food companies have enormous investments in their current dry formulationsand the long term purchase of ingredients that will make up those foods. All have huge dry cat food plants and acustomer base that they will not willingly convert to better types of food withsmaller profit margins. Had Dr. Pion not discovered the taurine-deficiencyconnection to certain canned cat foods, and threatened the implicated companieswith scathing public relations consequences if diet formulations were notimmediately revamped and improved, we would still be treating congestive cardiomyopathy as a fatal disease of cats of “unknownetiology.” Because of Dr. Pion’s discovery and willingness to speak out loudly,feline congestive cardiomyopathy is essentially ahistorical disease today.
If youworry about switching forms of food because you have been convinced that dryfood is essential to good dental health for your cat, consider this: veterinarianstoday, whose feline patients are almost always consuming dry food as theircomplete or nearly complete diet, are seeing as much oral and dental disease intheir patients as ever before. While thefeeding of a crunchy kibble may have an intuitive appeal for dental health, thereality is that there are no scientific studies that prove dry foods providebetter dental health throughout a cat’s life than wet foods do. In my practice, I have a majority of mypatients consuming exclusively wet diets. My patients require no more regular dental care and experience no moredisease of their teeth and gums than patients on other practices in which Ihave worked where dry food was the norm. There is no dental benefit from dry food that even begins to offset theterrible harm done from feeding the wrongmetabolic fuel to our cats.
It is forus, all of us, to do as Dr. Pion did back in the late1980s. This article is the beginning ofwhat I hope will become a groundswell of support to apply intense and constantpressure on the companies that supply our cat foods. I call for all of you to think long and hardabout whether you really believe your cats are doing well on “fritos, chips and breakfast cereal.” Those of you with obese and/or diabetic cats,consider that your cats would most certainly be more fit and healthier had theynot lived on junk food all their lives. If you hesitate to seriously consider making a change from dry foodbecause kibble is so convenient and easy to feed, please consider what this convenienceis costing your cat. Until the veterinary profession becomes more knowledgeableabout feline nutrition, and the pet food industry faces and corrects thedefects within its present dry formulations, you are your cat’s only realadvocate for nutritional health. So speak up!