So What Are Enzymes Anyway?

by Mark (Biscuit Boy) Rogers

Enzymes are among the most important biomolecules found in all living organisms.  They are large, structurally diverse proteins that catalyze or accelerate a wide variety of chemical reactions that are critical to sustaining life.  Enzymes are not living entities,  but they do, however require very stringent conditions in order to maintain their activity.  The scope, diversity, and specificity of the reactions they catalyze make them some of the most complex, fascinating, and essential molecules found within the cells and organs of all living things.  

Enzymes catalyze a truly astounding number of chemical reactions, and it is their ability to speed up these reactions under physiological conditions, (mild temperature, small pH variance, and in essentially aqueous solution) that make them both critical to life and truly remarkable.  The rate enhancement of enzyme catalyzed reactions can be as great as 10¹⁴ times that of the uncatalyzed reaction.  A key feature of catalysis is that the catalyst is unchanged throughout the course of the reaction, and can be used over and over again.  Despite the spectacular advances in our understanding of chemical processes over the last century the laboratory chemists of our age have not developed a repertoire of such diverse and reaction specific catalysts that work under mild conditions that even approaches those of living organisms.  Since structure is key to the understanding of how enzymes function, it is here where we will start our discussion.  

The majority of enzymes are proteins, large molecules made up of amino acids.  Amino acids are multifunctional organic molecules composed of the elements carbon, hydrogen, oxygen, nitrogen, and in some cases sulfur.  Proteins have four levels of structure.  Amino acids bond together in long chains, called peptides, to form the primary structure of proteins.  The order and spatial arrangement of the amino acids is unspecified.  As the chain length increases the proteins take on secondary structure.  Secondary structure  refers to regular, recurring arrangements in space of adjacent amino acids in a polypeptide chain.  Tertiary structure refers to the spatial arrangement among all amino acids in a polypeptide chain. It is the complete three-dimensional structure of the polypeptide.  Proteins with several polypeptide chains have one  more level of structure, quaternary structure, which refers to the spatial relationship of the polypeptide chains or subunits in the protein.  The feature of enzymes that sets them apart from other proteins is that they catalyze chemical reactions.  This is a direct result of the unique structure of each enzyme.  That in turn is a result of the amino acids present, their order, and how this results in the overall three-dimensional structure.  The business end of an enzyme is the active site.

The high rate of molecular turnover, the degree of reaction specificity, and the incredible rate enhancement of enzymes, all arise out of the unique structure of each enzyme.  Although enzymes are large molecules and the overall totality of the structure is critical to its activity, the active site, the place where the reaction that is catalyzed takes place is often comprised of only a small number of amino acids.  Often times only one or two of these actually participate directly in the chemical reaction.  The remaining amino acids are present to carry out two main functions.  First, they help bind the substrate, the molecule undergoing the chemical transformation, and second they stabilize the transition state structure.  The transition state structure is the transitory structure of the molecule being transformed as it goes from reactant, (the molecule before the chemical reaction), to product, (the molecule after the chemical reaction).  Stabilization of the transition state is what produces the incredible rate enhancements exhibited by enzymes.  Transition state stabilization is structure specific and therefore a function of the amino acids present in the active site.  Without the enormous catalytic rate enhancement produced by enzymes enough cellular processes could not take place to sustain the delicate balances required for life, and thus our pets, ourselves and all other life would simply cease to exist.

In addition to catalysis another very important feature of enzymes is the specificity of the reactions they carry out.  The specificity can be broken down into two main components.  The first component relates to the type of reaction the enzyme catalyzes.  Similar to to transition state stabilization, specificity of reaction type is characterized by the amino acids present in the active site as well as any co-enzymes associated with the enzyme and or any metal or metals in the active site.  The second component is related to substrate, (reactant molecule), specificity.  Families of enzymes can can catalyze a specific type of reaction or reactions, but each structurally unique enzyme may only recognize one specific substrate molecule.  For this reason enzymes work in a series.  That is to say they act in organized sequences, each carrying out one step in a series of single step transformations to either build up or breakdown molecules.  One direction takes large molecules and breaks them down into simpler components and the other takes simple building blocks and constructs large complex molecules required for an organism to function.

An important feature in substrate specificity is the energy required in binding the substrate in or near the active site.  The binding energy of the product produced by the chemical reaction catalyzed by the enzyme must be much less then that of the substrate.  This is important to understand.  The binding energy of the substrate to the enzyme must be sufficiently strong and unique to to allow substrate specificity but not to strong that the reaction cannot take place and so that the product molecule can diffuse out of the active site.

The true beauty of enzymes is their ability to meet all these criteria simultaneously.  The amino acids in and around the active site bind the substrate molecule by interacting with its unique structural features.  This is interaction is strong enough and unique enough that the substrate binds near the active site and is held in the correct spatial orientation so that the chemical reaction can proceed.  The binding energy of the product molecule is, in contrast, just weak enough that the product is released leaving the enzyme to carry out another catalytic cycle.  Finally, and perhaps most importantly, the active site is constructed so that the transition state structure (the transient structure that is part way between the reactant molecule and the product) is stabilized.  This lowers the energy required for the chemical reaction to take place and is the basis for the catalytic nature of an enzyme.  The enzyme is unchanged throughout this entire process and is, therefore, ready upon release of the product, to carry out another catalytic cycle.

Although quite remarkable in and of themselves enzymes do not always act alone.  In many instances they need “helper molecules”, or metal ions.  These helper molecules can take the form of metal ions in or near the active site, or co-enzymes, or both.  Metals ions are normally permanently bound to the enzyme and play a vital role in their activity.  Examples include, copper, zinc, iron, magnesium, etc.  Replacement of these ions by heavy metals such as lead, mercury, or thallium, or arsenic, (found in some rat poisons) cause the enzyme to loose activity and are the result of heavy metal poisoning in our pets and ourselves.  Co-enzymes include many of the vitamins used in the supplements we give our pets in addition to the foods we feed them.  Co-enzymes are organic molecules that can either be covalently bonded to the enzyme or diffuse in and out of the active site region as needed.  Both metal ions and co-enzymes are critical to the activity of many enzymes and although they are found in most foods it is also of great benefit to add them to pet foods or administer them separately as supplements.  Because of their critical role in enzymatic activity vitamin deficiency can cause a variety of disease states.  Two common examples are scurvy and rickets - the result of vitamin C and vitamin B₁ deficiency respectively.

As mentioned, enzymes are proteins and, therefore, prone to denaturation.  Denaturation is the break down of the structure of proteins on any of the four structural levels mentioned previously.  Any change in the structure of enzymes, causes a loss in function, and or activity.  Denaturation can occur by heating proteins or by treating them with alkali or acid.  When proteins are heated such as in cooking even at low temperatures, they rapidly lose their structural integrity.  This is not a problem in nutritive proteins but is a series problem with enzymes.  Once an enzymes structure is compromised, it permanently loses activity.  Enzymes are rapidly denatured in the stomach and, thus, lose all activity.  Most digestive enzymes are active in the small intestine, far removed from the caustic effects of stomach acids.  Only a small number of enzymes are so constructed that they can briefly survive the harsh conditions of the stomach, and these have highly specialized “built in” protections.  

For these reasons, the enzymes found in the foodstuffs used in pet food formulations do not survive the cooking process used to prepare canned and kibbled pet foods.  Likewise, they do not survive the conditions in the stomach and are therefore unavailable to aid in digestion or any other process.  In order for enzymes to be of any use as a supplement they must be added to the food after cooking in very large quantities or coated in some way to protect them from the initial digestive process of the stomach.  The only other method of introduction of enzymes or proteins in general is by means of injection - which is of no use with digestive enzymes.  Unless there is a disease state present, all the enzymes needed for digestion are produced by the animal, where and when they are needed.

Enzyme deficiencies can cause a variety of disease states  Some of these disease states are the result of a deficiency of a particular enzyme or family of enzymes.  In other instances, a disease state or malfunction of a particular organ can cause a decrease in the production or release of enzymes.  An example of the latter is pancreatitis, which is an inflammation of the pancreas.  Pacreatitis causes a decrease in the production and/or release of the digestive enzymes protease, lipase, and amylase.  These represent a family of enzymes responsible for the digestion of the three types of foods animals eat.  Proteases digest proteins, lipases digest fats, and amylases digest carbohydrates, (sugars).  They are produced in, and excreted by, the pancreas.  Pancreatitis can sometimes be effectively treated by supplementation of these enzymes by adding them to pet foods just prior to feeding.  They need to be administered in relatively high doses so that some of them survive the acid conditions of the stomach.  In human pancreatitis they are coated so that they do not release until they reach the small intestine.  This is just one example.  There are many problems associated with the lack of production, over production, release of, or regulation of enzymes.

Since enzymes catalyze virtually every biochemical process inside the cell it is no surprise that they are very highly regulated.  This regulation is extremely complex and beyond the scope of this discussion.  However, it is valuable to mention that inhibition of enzymes and modulation of their regulatory processes represents one of the most important areas in drug design.

Remember enzymes are not living entities!  They are truly remarkable molecules that require very specific conditions, co-factors or co-enzymes, and regulatory molecules to keep them functioning properly.  The finely orchestrated interplay of the myriad of conditions that ensure proper enzymatic activity make enzymes one of the most remarkable and fascinating of all biomolecules that make life possible.  Even the slightest disruption of any these conditions can have deleterious or even fatal consequences for living organisms.  Their importance and complexity can not be overstated.  However, their beauty can be simply appreciated!

How Many Carbs Are In My Pets Food?

How Many Carbs Are In My Pets’ Food?

Ever Wonder… How much carbohydrates are in your pet’s food?

Well, here is how to figure it out for yourself!

The amount of carbohydrates (SUGAR) in pet foods is not listed anywhere on the bag because neither dogs nor cats need them in their diet.  Since they are both carnivores, they have NO dietary requirement for carbohydrates (sugar).  This is why the pet food manufacturers aren’t required to put it on the label, and as you will see they do not want you to know how much sugar is in their foods.  Sugar is cheap, and many foods are close to 50% or greater sugar!  Below is how to calculate how much of your pet’s food is carbohydrates (sugar).

Knowing that everything in the food adds up to 100%, all you need do is subtract what is known from the Guaranteed Analysis Statement on the bag, plus the average value of ash found in quality foods (6-8%), use 7% as a middle value, and what you have left is the carbs - SUGAR.  Fiber is a type of sugar so it is NOT subtracted!

100 - % protein - % Fat - 8% ash - % Moisture = % Carbs 

From an actual Guaranteed Analysis of an expensive food.

24% Protein

15% Fat

10% Moisture

~ 8% Ash (not listed on the label)

100 - 24% protein - 15% Fat - 8% Ash - 10% moisture = 43 % Carbs (SUGAR)  

That means 4.3 pounds of sugar in a 10 pound bag of food! 

Sugar isn’t necessary in our pet’s diet nor is it good for our pets.  With diabetes up 32% in dogs since 2006 and 16% in cats* isn’t it time we start looking more carefully at our pet’s foods and paying for what they need in their diet like meat and not sugar!

*Source: Analysis from 770 Banfield Animal Hospitals medical data on 2.2 million dogs and 450,00 cats!

Myth Busters

MYTH BUSTERS

by: Mark E. Rogers

There are many myths about companion animal health and nutrition.  Some of these myths are amusing, make you laugh, and walk away smiling.  Many are of them are just wrong or dangerous and jeopardize the quality and longevity of our best friend’s lives.  The origins of these myths are varied, and often obscured in anecdotal clouds of here-say and folklore.  But origins are unimportant.  What is important, is looking to the best available scientific evidence and research findings to dispel these myths and protect the health and well being of our faithful companions, provide them the best environment and nutrition so they can thrive, and not let the many animals lives that have been given up for a better understanding of their needs to have been done so in vain.  For after all the world is Not flat and the Moon is Not made of cheese.

MYTH - “Dogs are not true carnivores.”

FALSE - Dogs and Cats ARE Carnivores!

The anatomical features of carnivores are:

SHORT , SIMPLE , & ACIDIC DIGESTIVE TRACTS. Protein and fat from animal source are quickly and easily digested – hence the short digestive system of dogs and cats.

The ability of dogs and cats to secrete hydrochloric acid is also exceptional. To facilitate protein breakdown and kill the bacteria found in decaying meats, dogs and cats are able to keep their gastric pH around 1-2.

SHARP TEETH (designed for slicing meat, not grinding plants). Carnivores have elongated teeth designed for tearing and killing prey.

Their molars are triangular with jagged edges that function like serrated-edged blades that give a smooth cutting motion like the blades on a pair of shears.

JAWS MOVE VERTICALLY unlike herbivores and omnivores that grind their food by side to side chewing, the jaws of dogs and cats operate vertically to provide a smooth cutting motion, and open widely to swallow large chunks of meat.

NO AMYLASE IN SALIVA. Amylase in saliva is something omnivorous and herbivorous animals possess, but not carnivorous animals like dogs or cats.

As amylase is not present in saliva, the burden is entirely on the pancreas to produce the amylase needed to digest carbohydrates.

Feeding dogs as though they were omnivores or herbivores makes the pancreas work harder in order to digest the carbohydrate-filled foods (instead of just producing normal amounts of the enzymes needed to digest proteins and fats).

Several key anatomical features separate dogs and cats from omnivores and herbivores, while clearly classifying them as carnivores with an adaptation for an almost exclusively meat based diet.

Dogs & cats posses a short, simple gastrointestinal tract. Because meat is easily digested (relative to plants) their small intestines are short.

A high concentration of stomach acid helps quickly break down proteins (Carnivores have a stomach acidity of about pH 1 - compared to humans at pH 4 to 5).

A large mouth opening with a single hinge joint adapted for swallowing whole chunks of meat.

Short and pointed teeth designed for grasping, ripping and shredding meat (not grinding grains).

Teeth and jaws designed to swallow food whole (not for chewing or crushing plants).

Adapted to break down protein and fat from meat (not plants or grains), the

saliva of dogs and cats does not contain the digestive enzyme amylase.

Carnivores don‘t chew their food. Unlike carbohydrate-digesting enzymes, protein-digesting enzymes cannot be released in the mouth due to the potential of damaging the oral cavity (auto digestion).

Therefore, carnivores do not mix their food with saliva—they simply bite off huge chunks of meat and swallow them whole.

Where the notion that dogs are omnivores ever started is unclear.  The FACT is that they are Not omnivores they ARE carnivores and should be treated and fed as such!

MYTH - “High protein diets will burn up or destroy my dogs kidneys.”

FALSE -  Not only is there no scientific evidence to support this claim, there are numerous scientific studies that demonstrate diets containing high quality animal protein have no deleterious effect on canine or feline kidney function. ^1-6  High protein diets are far more biologically appropriate then diets low in protein (< 30%).  Since Dogs and Cats ARE carnivores, protein and fat are what they are biologically designed to eat. Further, numerous studies have shown that except in extreme cases of very advanced kidney disease and renal failure, low protein diets can cause more harm then good.^4-6  Low protein diets may extend the life of animals whose normal kidney function has dropped below 25% of normal but unfortunately, at that stage little to nothing that can be done for the animal except to make its remaining time as comfortable as possible.  

1. Mythology of Protein Restriction for Dogs with Reduced Renal Function

Kenneth C. Bovée, DVM, MMedSc

Department of Clinical Studies School of Veterinary Medicine University of Pennsylvania Philadelphia, Pennsylvania Supplement to Compendium on Continuing Education for the Practicing Veterinarian Vol. 21, No. 11(K), Nov. 1999.

2. Robertson JL, Goldschmidt M, Kronfeld DS, et al: Long- term renal responses to high dietary protein in dogs with 75% nephrectomy. Kidney Int 29:511–519, 1986.

3. Delmar R. Finco et. al. Effects of Aging and Dietary Protein Intake on Uninephrectomized Geriatric Dogs Am J Vet Res. 1994 Sep;55(9):1282-90

4. Delmar R. Finco et. al. Protein and Calorie Effects on the Progression of Chronic Renal Failure in Cats American Journal of Veterinary Research vol 59 (5) may 1998

5.  Peter J. Markwell BSc, BVetMed, MRCVS Dietary Management of Renal Failure in the Dog and Cat  WALTHAM Centre for Pet Nutrition, UK

6. The Eleventh Annual Canine Medicine Symposium May 10-11, 2008 - UCDAVIS

Denise A. Elliott, BVsc, PhD, DACVIM, DACVN Nutritional Management of Renal Disease:  Myths, Realities, and Tips for Success

MYTH - “High protein diets fed to puppies lead to rapid bone growth and skeletal disease especially in large breed dogs, e.g., Great Danes.”

FALSE - There is no scientific evidence to support the claim that high protein diets cause rapid growth of any kind.  In fact, it was demonstrated as early as 1991 that high protein diets have nothing to do with rapid bone growth and did not contribute to osteochondrosis specifically in Great Dane puppies.¹  On the contrary, a diet high in quality animal protein increases the palatability and aids in restricting the fat content of foods without the inclusion of unnecessary carbohydrates.  It has been shown that higher protein to calorie ratios are even more important for puppies and kittens then for adult animals.  The proteins and fats need to be high quality to ensure a high degree of digestibility and bioavailability of essential amino acids and essential fatty acids.  The primary cause for non-genetic skeletal abnormalities in large breed dogs is overfeeding.^2-4  Providing energy and nutrition in excess of need is the cause of rapid growth rate, and the source of energy, protein, fat, or carbohydrate, is of less importance then the total metabolizable energy fed.  No correlation has ever been made between growth rate in puppies and achievement of full growth potential in adult dogs.^2-5  Home cooked or prepared meals can often be more at fault, though their nutritional value can be far superior, then commercially available foods due to the simple fact that the total metabolizable energy is more difficult to determine accurately.

Energy requirements for dogs and cats can be determined with a fair degree of confidence.  The energy requirement calculations take into account several variables that are beyond the scope and intent of this discussion.  The reader is referred to reference 5 for a detailed description and simple to follow instructions to determine the approximate energy requirements for their animal.  This is of critical importance in light of the current discussion to ensure that growing puppies( especially large breeds) and kittens nutritional needs are met without overfeeding.  This is unquestionably the most prudent practice, a lean dog is far healthier then an over fed dog, and this is the best measure to prevent skeletal and muscular disease related to over nutrition.  Unfortunately, their is no magic formula, and certainly no magic food formulation available that can be fed according to generalized feeding guidelines.  Each dog is an individual.  The responsible animal owner can and should make the relatively small investment in time and energy required to provide their growing animals with optimal nutrition in the correct proportions to the best of their ability.  Do not fall prey to superstition, fear, myths, and emotion.

The calculated energy requirements alone should not be used as the sole determinant of how much food should be fed.  They do provide a solid, scientifically based starting point and useful tool to help prevent to rapid a growth rate and weight gain in the growing animal. 

1. Nap RC, Hazewinkel HAW, Voorhout G et al. Growth and skeletal development in Great Dane pups fed different levels of protein intake. J Nutr 1991; 121: S107-113.

2. Encyclopedia of Canine Clinical Nutrition, Pibot P., Biourge V. and Elliott D.A. (Eds.). International Veterinary Information Service, Ithaca NY, Last updated: 17-Jul-2008; A4211.0708

Main Nutritional Imbalances in Osteoarticular Diseases

H.A.W. Hazewinkel1 and J. Mott2

1Utrecht University, Utrecht, Netherlands. 2South Pasadena, CA, USA.

3. Proceeding of the NAVC

North American Veterinary Conference Jan. 8-12, 2005, Orlando, Florida

NUTRITION AND DEVELOPMENTAL ORTHOPEDIC DISEASES IN LARGE BREED DOGS

Allan J. Lepine, PhD

4. Proceeding of the SEVC Southern European Veterinary Conference

Oct. 17-19, 2008 – Barcelona, Spain

ORTHOPEDICS

Growth Abnormalities: The Role of Nutrition

Prof. Dr. med. vet. J. Zentek

5. National Research Council of the National Academies (NRC). Nutrient Requirements of Dogs and Cats(2006). The National Academies Press, Washington D.C. Ch. 3 & Ch. 11.

MYTH - “Older dogs need less protein.”

FALSE -  While older dogs energy requirements tend to decrease, their protein requirement increases by as much as 50%! ¹  Not only is protein restriction in older dogs not necessary it can be very debilitating leading to age related loss of lean body mass and contribute to early mortality.

1. Pet food safety: dietary protein. Laflamme D.P. Top Companion Anim Med. 2008 Aug;23(3):154-7

MYTH - “Dogs (and cats) need carbohydrates (sugar) for energy.”

FALSE - Neither has a requirement for carbohydrates (NRC, AAFCO).  Although both utilize glucose for a variety of biological functions including energy they have no dietary requirement since they can produce all they need from the metabolites of protein and fat through a process called gluconeogenesis.  Glucose is stored in the liver of animals as glycogen, a polymer of glucose, and is released and utilized under the control of the pancreatic hormone glucagon.  Insulin, another pancreatic hormone, is used to lower blood glucose and promote its storage in the liver, glucagon is used to raise blood glucose levels and promote its release.

Fluctuations of blood glucose levels that result from eating high starch (plant polymer of glucose) foods especially those with a high glycemic index, tax a carnivores pancreas to release both amylase to digest the starch and insulin to sequester the resulting glucose from the blood stream.   This in turn can lead to storage of excess sugar as fat not lean body tissue, and promote diseases such as obesity and diabetes.¹   The more biologically appropriate energy source for dogs is fat.^2-4  While carbohydrates are not in and of themselves bad, they are not a natural component of a carnivores diet and therefore their inclusion in there diet such be kept at a minimum.

1. Patrick Nguyen, Henri Dumon, Vincent Biourge and Etienne Pouteau, Glycemic and Insulinemic Responses after Ingestion of Commercial Foods in Healthy Dogs: Influence of Food Composition, J. Nutr. 128: 2654S–2658S, 1998.

2. Theriault DG, Beller GA, Smoake JA, et al. Intramuscular energy sources in dogs during physical work. J Lipid Res 1973; 14:54-61. 

3. Hammel EP, Kronfeld DS, Ganjan VK, Dunlap HL. Metabolic responses to exhaustive exercise in racing sled dogs fed diets containing medium, low, or zero carbohydrate. Am J Clin Nutr 1976; 30:409-418.

4. Reynolds AJ, Fuhrer L, Dunlap HL, Finke M, Kallfelz FA. Effect of diet and training on muscle glycogen storage and utilization in sled dogs. J Appl Physiol 1995; 79:1601-1607.

MYTH - “Canned food has less protein and fat then dry food.”

FALSE - Canned foods and raw foods have more fat and protein then the majority of dry foods.  To accurately compare canned, raw, and dry foods they must all be on a level playing field.  That means you must compare the protein, fat, and carbohydrates on a dry matter basis.  Canned and raw foods are typically between 65 and 85% water where dry foods are only 10-12% water.  To make an accurate comparison you must remove the water content from the formulation then compare the % composition of each nutritive ingredient.  This is easy to accomplish.  Recall that the listed percentages on the label are as fed.  since the total contents must equal 100% simply remove the % moisture and recalculate the % of the ingredient now based on a dry matter amount.  So in a can of food that lists protein as 10%, fat as 8%, and moisture as 78% the calculations are as follows:  100 - 78 = 22.  So 10(p) ÷ 22 = 45% protein, 8(f) ÷ 22 = 36% fat, on a dry matter basis.  In a dry food that lists protein as 28% and fat as 14% and moisture as 10% the calculation becomes:  100 - 10 = 90.  28(p) ÷ 90 = 31% protein, 14(f) ÷ 90 = 15.5% fat, on a dry matter basis.  This type of comparison can be made between any foods whose moisture content and as fed ingredient % are known.

What about the missing ingredient carbohydrates(sugar)?  This can easily be estimated by the following equation.  First, remember fiber is a form of carbohydrates and second, the ash content if not listed can be estimated to be no more then 8%.  This will get you within about 1-3%.  So in a typical grain free food: 100% (total) - 10% (water) -32% (protein) - 18% (fat) - 8% ash = 32% carbohydrates = (SUGAR)!  That means in a 30 lb bag of food there is ~10 lbs of SUGAR! - Food for thought!

MYTH - “Gastric Dilation Volvulus (BLOAT) is caused by - dehydrated raw foods, cereal based foods, high protein foods, citric acid, and/or a host of other food related issues.”

FALSE - Gastric Dilation Volvulus GDV or Bloat is NOT caused by any of these!  While the exact cause or causes of GDV are not clearly known or understood, Dr. Glickman at Purdue University who is considered one of the foremost experts on this often fatal condition has over the past 30 years identified several causative factors and ruled out others.  Dogs with narrow deep chests are at greatest risk for GDV as are those with a history of the condition in a first degree relative.  Other causative factors include but are not limited to; eating large meals once daily, eating from raised bowels, high speed of eating, eating less canned foods, fewer snacks, temperament - aggression toward people or other dogs, stressful situations.  Factors that DO NOT contribute to the incidence of GDV are; feeding cereal based foods, dry food moistened with water, supplements, vitamins, multiple animal households, other pre -existing diseases, vaccinations, citric acid, raw food.  One recent study has determined that the only food related causative factor is a 2.4 fold increase in GDV for dogs fed a dry food listing oils or animal fat as the fourth ingredient “can predispose a high risk dog to GDV”.¹  The only two effective preventative measures to date are to avoid breeding effected animals and those that have an effected first degree relative, and surgical tacking - or gastroplexy.

1. Journal of the American Animal Hospital Association January/February 2006 vol. 42 no. 1 28-36 

The Effect of Ingredients in Dry Dog Foods on the Risk of Gastric Dilatation-Volvulus in Dogs

Malathi Raghaven DVM, PhD, Nita W. Glickman MPH, PhD and Lawrence T. Glickman, VMD, DrPH.

2. GASTRIC DILATATION/VOLVULUS SYNDROME IN DOGS Greg Marsolais, DVM, MS, Diplomate ACVS, Small Animal Surgery 2007Reviewed and updated 12/25/2008 by Mitchell A. Robbins DVM, Diplomate ACVS - ACVS Article available on web

3. Proceedings of the 34th World Small Animal Veterinary Congress WSAVA 2009 São Paulo, Brazil - 2009 GASTRIC DILATATION VOLVULUS: WHAT’S NEW? Theresa W. Fossum DVM, MS, PhD, Diplomate ACVS Texas A&M University College of Veterinary Medicine, College Station, TX 77843-4474

4. Encyclopedia of Canine Clinical Nutrition, Pibot P., Biourge V. and Elliott D.A. (Eds.). International Veterinary Information Service, Ithaca NY  Last updated: 8-Jan-2008; A4203.0108

The Most Common Digestive Diseases: The Role of Nutrition

A.J. German1 and J. Zentek2

1Faculty of Veterinary Sciences, University of Liverpool, United Kingdom. 2Faculty of Veterinary Medicine, University of Berlin, Germany.

MYTH - “Beet pulp turns my dogs coat red.”

FALSE - The beet pulp used in pet food formulations is colorless and has NO effect on coat color.  The truth is that tyrosine (an amino acid) deficiency NOT beet pulp is responsible for the so called red coat syndrome.^1-2 Tyrosine is a key precursor of the skin and hair pigment melanin.  Insufficient amounts of tyrosine can lead to a lightening of the coat of dark colored dogs and cats  due to lack of sufficient melanin synthesis.  Supplementation of free tyrosine above the AAFCO minimum requirements can alleviate this syndrome.

More importantly, dietary fiber inclusion in pet food formulations has been shown to improve intestinal health, specifically the large intestine, and increase nutrient absorption.^2-3  Often called prebiotics because they feed the intestinal microflora and produce small chain fatty acids (SCFAs) which improve fecal composition and the health of the large intestine mucosal membrane.  Combinations of prebiotics and probiotics offer many advantages to the overall health of the GI tract of companion animals and beet pulp and rice bran appear to be optimal fiber (prebiotic) sources for this purpose.⁴ 

1. Proceedings of the 27^th  WSAVA Congress 2002 Biourge, Renauld Sergheraert, Red Coat Syndrome:  A Dietary Cause 

2. Fabienne Dethioux, Nutrition, Skin Health and Coat Quality, Veterinary Focus, Vol18 No 1, 2008.

3. Kelly S. Swanson, Christine M. Grieshop, Elizabeth A. Flickinger, Laura L. Bauer, JoMay Chow, Bryan W. Wolf, Keith A. Garleb and George C. Fahey, Jr. Fructooligosaccharides and Lactobacillus acidophilus Modify Gut Microbial Populations, Total Tract Nutrient Digestibilities and Fecal Protein Catabolite Concentrations in Healthy Adult Dogs, J. Nutr. 132: 3721–3731, 2002.

4. G. D. Sunvold, G. C. Fahey, Jr, N. R. Merchen, E. C. Titgemeyer, L. D. Bourquin, L. L. Bauer and G. A. Reinhart Dietary fiber for dogs: IV. In vitro fermentation of selected fiber sources by dog fecal inoculum and in vivo digestion and metabolism of fiber-supplemented diets, J ANIM SCI 1995, 73:1099-1109.

MYTH -  “Obese dogs and cats should be fed low protein, low calorie diets.”

FALSE - It has been repeatedly demonstrated that the best dietary management for both obese dogs and cats is to feed high protein, low carbohydrate diets.^1-5 This dietary protocol along with regular exercise is the best method for not only achieving the desired weight loss but also ensuring the animal retains and even gains the more desired lean body mass. Although the weight loss observed through high protein low carbohydrate diets, is at a slightly slower rate then that observed with reduced calorie high carbohydrate diets the resulting body tissue is of a more desirable lean muscle to fat ratio.  The animals appetite is more correctly satiated by the more biologically appropriate food - protein.  Sugar causes a blood sugar rise and crash that makes the animal believe it’s hungry when in fact its energy requirements have been met.  This makes weight loss more difficult to achieve for the owner and animal alike.  Finally, and just as importantly a high protein diet will greatly reduce the risk of the obese animal developing the many debilitating illnesses associated with obesity especially diabetes.

1. Marianne Diez, Patrick Nguyen, Isabelle Jeusette, Claire Devois, Louis Istasse and Vincent Biourge Weight Loss in Obese Dogs: Evaluation of a High-Protein, Low-Carbohydrate Diet J. Nutr. 132: 1685S–1687S, 2002.

2. Dorothy P. Laflamme, DVM, PhD Steven S. Hannah, PhD  Increased Dietary Protein Promotes Fat Loss and Reduces Loss of Lean Body Mass During Weight Loss in Cats Intern J Appl Res Vet Med • Vol. 3, No. 2, 2005

3. Tiffany Linn Bierer and Linh M. Bui High-Protein Low-Carbohydrate Diets Enhance Weight Loss in Dogs J. Nutr. 134: 2087S–2089S.

4. Patrick Nguyen, Véronique Leray, Henri Dumon, Lucile Martin, Brigitte Siliart, Marianne Diez and Vincent Biourge High Protein Intake Affects Lean Body Mass but Not Energy Expenditure in Nonobese Neutered Cats J. Nutr. 134:2084S-2086S, August 2004.

5.Geraldine Blanchard, Patrick Nguyen, Constance Gayet, Isabelle Leriche, Brigitte Siliart, and Bernard-Marie Paragon, Rapid Weight Loss with a High-Protein Low-Energy Diet Allows the Recovery of Ideal Body Composition and Insulin Sensitivity in Obese Dogs, J. Nutr. 134: 2148S–2150S, 2004.

MYTH - “Only prescriptive diets should be fed to diabetic dogs and cats.”

FALSE -  As controversial as this may sound current scientific research would say NO!  The current research available in this area indicates that high protein low carbohydrate diets, first and foremost, are the best choice for both diabetic cats and dogs.^1-5 A quick review of the most popular prescriptive diets for dogs and cats will show anyone looking at these foods that they DO NOT fit this criteria!.  In cats over 50% of the animals fed high protein low carb diets were able to completely stop receiving insulin injections and >30% of those still receiving injections were able to reduce their dosage.  In dogs similar results have been observed.² Diabetic diets for cats and dogs should be carefully tailored to meet the specific needs of each individual as many other debilitating conditions can arise and occur concomitantly with diabetes.  Many animals also suffer from obesity, see above, and other conditions that require special attention.  However, the overwhelming body of evidence shows that diabetic animals like people should restrict their carbohydrate (SUGAR) intake!  This is especially true for carnivorous animals (cats and dogs) which are not designed to consume carbohydrates.  Just because they can eat carbohydrates does not mean they should!  One popular and very expensive prescriptive “diabetic diet” which will not be named lists the following information - you be the judge!

Ingredients:  Rice, ground corn, chicken meal, powdered cellulose, corn gluten meal, wheat, natural flavors, chicken fat, rice hulls, monocalcium phosphate, vegetable oil, potassium chloride, guar gum, calcium carbonate, salt, choline chloride, taurine, vitamins [DL-alpha tocopherol acetate (source of vitamin E), biotin, D-calcium pantothenate, pyridoxine hydrochloride (vitamin B6), vitamin A acetate, niacin supplement, thiamine mononitrate (vitamin B1), riboflavin supplement (vitamin B2), folic acid, vitamin B12 supplement, vitamin D3 supplement], trace minerals [zinc oxide, ferrous sulfate, copper sulfate, manganous oxide, calcium iodate, sodium selenite], rosemary extract, preserved with natural mixed tocopherols and citric acid.

per 1000 kcal

Protein g 67.4

Fat g 31.2

Crude Fiber g 34.9

Total Dietary Fiber g 63.5

Carbohydrate g 142.4

Since protein and carbohydrates have an equal number of calories per g (~4 kcal/g) you can see this diabetic food has more then twice its calories from sugar then from protein (570 vs 270)!

1. Renee Rucinsky, DVM, ABVP (Feline) (Chair), Audrey Cook, BVM&S, MRCVS, Diplomate ACVIM-SAIM, Diplomate ECVIM-CA, Steve Haley, DVM,Richard Nelson, DVM, Diplomate ACVIM, Debra L. Zoran, DVM, PhD, Diplomate ACVIM, Melanie Poundstone, DVM, ABVP AAHA Diabetes Management Guidelines for Dogs and Cats, Journal of the American Animal Hospital Association 2010; 46:215-224.

2. Deborah S. Greco, Dietary Treatment of Diabetes Mellitus in Dogs and Cats: Part of the 2009 Nestlé Purina Veterinary Symposium Publication Jun 1, 2009.

3. Jacquie S. Rand, Linda M. Fleeman, Heidi A. Farrow, Delisa J. Appleton, and Rose Lederer, Canine and Feline Diabetes Mellitus: Nature or Nurture?  J. Nutr. 134: 2072S–2080S, 2004.

4. Encyclopedia of Canine Nutrition: L.M. Freeman and J.S. Rand Diabetes Mellitus: Nutritional Strategies Last updated: 31-Mar-2008; A4206.0308.

5. Geraldine Blanchard, Patrick Nguyen, Constance Gayet, Isabelle Leriche, Brigitte Siliart, and Bernard-Marie Paragon, Rapid Weight Loss with a High-Protein Low-Energy Diet Allows the Recovery of Ideal Body Composition and Insulin Sensitivity in Obese Dogs, J. Nutr. 134: 2148S–2150S, 2004.

MYTH - “Serological (blood) tests can be used to determine food allergies in dogs.”

FALSE - It has been known for decades that blood tests and skin test are inaccurate to the point of being USLESS for determining food allergies in companion animals.¹  Only strict elimination diets followed by single protein ingredient provocation and rescue protocols can be used to accurately determine true food allergies.  Many food allergies are more correctly termed food sensitivities and can be alleviated when the underlying allergy or other immune system debilitating condition has been treated.  Food allergy in dogs is estimated to be quite low <10% of all animals.  However, the incidence of dermatological allergic conditions has been shown to be greater in counties that have small animal dermatology practices.²

1.Proceedings of the Southern European Veterinary Conference - SEVC Sep. 30-Oct. 3, 2010, Barcelona, Spain Dermatology, Peter J. Ihrke, VMD, Diplomate A.C.V.D.

2. Marie Sallander*, Josefina Adolfsson, Kerstin Bergvall, Åke Hedhammar and Ane Nødtvedt The Effect of Early Diet on Canine Atopic Dermatitis (CAD) in Three High-Risk Breed The Open Dermatology Journal, 2009, 3, 73-80.

MYTH - “My dog/cat is allergic to chicken fat, or other animal fat, all grains, etc.”

FALSE - Allergic responses can only be to proteins or small molecules that either bind to cell surfaces or circulating proteins in the blood stream.  Food allergens must be proteins that are stable to heat, strong acid, and the action of protease enzymes and meet specific size criteria that allows them to pass through the lumen of the small intestine.  See any general biology text on allergies.

Grain Free Dog - To Feed or Not To Feed? That Is THE Question!

Grain Free Pet Food - To Feed Or Not To Feed  - That is THE Question

By Mark E. Rogers - Green Dog Promotions, LLC

Much has been said recently in the media and medical circles about the alarming increase in obesity in humans and their companion animals, cats and dogs.  The number and severity of deleterious health conditions that result from the general state of obesity appear in many cases to be consistent across species.  Some of the more serious conditions include but are not limited to; diabetes, heart and other cardiovascular diseases, liver disease, pancreatic disorders other then diabetes, kidney disease, and increased joint stress.  The near epidemic incidence of obesity in humans has lead to numerous scientific studies and dietary recommendations, diet plans and medications.  Many diets and medications make far reaching and amazing claims of near instant success and prey upon peoples emotions with promises of beautiful outward appearances and overnight good health.  One very useful concept, founded in science, that has arisen out of this flurry of science and emotion that has been made popular by the “Atkins” and “South Beach” diets and is now the basis of many “medical breakthrough diets” and “Gimmick Pills” is the Glycemic Index (GI).  The GI is a quantifiable measure of blood glucose level (blood sugar level) after consumption of a carbohydrate (sugar) containing food stuff such as bread, table sugar, fruit, grains, etc.  This article briefly addresses the GI in relation to pet foods and pet diets.

Glycemic Index

In the past, carbohydrates were classified as simple or complex based on the number of simple sugars in the molecule.  Carbohydrates composed of one or two simple sugars like fructose or sucrose (table sugar; a disaccharide composed of one molecule of glucose and one molecule of fructose) were labeled simple, while starchy foods were labeled complex because starch is composed of long chains of the simple sugar, glucose.  Advice to eat less simple and more complex carbohydrates (i.e., polysaccharides) was based on the assumption that consuming starchy foods would lead to smaller increases in blood glucose than sugary foods. This assumption turned out to be too simplistic since the blood glucose (glycemic) response to “complex” carbohydrates has been found to vary considerably.  A more accurate indicator of the relative glycemic response to dietary carbohydrates should be glycemic load, which incorporates the relative quality and quantity of carbohydrates in the diet characterized by the glycemic index (GI).

Measuring the Glycemic Index

To determine the glycemic index of a food, volunteers are typically given a test food that provides 50 grams of carbohydrate and a control food (white bread or pure glucose) that provides the same amount of carbohydrate on different days. Blood samples for the determination of glucose are taken prior to eating and at regular intervals after eating over the next several hours. The changes in blood glucose over time are plotted as a curve. The glycemic index is calculated as the area under the glucose curve after the test food is eaten, divided by the corresponding area after the control food is eaten. The value is multiplied by 100 to represent a percentage of the control food. For example, a baked potato has a glycemic index of 76 relative to glucose and 108 relative to white bread, which means that the blood glucose response to the carbohydrate in a baked potato is 76% of the blood glucose response to the same amount of carbohydrate in pure glucose and 108% of the blood glucose response to the same amount of carbohydrate in white bread . In contrast, cooked brown rice has a glycemic index of 55 relative to glucose and 79 relative to white bread. In the traditional system of classifying carbohydrates, both brown rice and potato would be classified as complex carbohydrates despite the difference in their effects on blood glucose levels.

Physiological Responses to High- versus Low-Glycemic Index Foods

By definition, the consumption of high-glycemic index foods results in higher and more rapid increases in blood glucose levels than the consumption of low-glycemic index foods. Rapid increases in blood glucose are potent signals to the beta-cells of the pancreas to increase insulin secretion. Over the next few hours, the high insulin levels induced by consumption of high-glycemic index foods may cause a sharp decrease in blood glucose levels (hypoglycemia). In contrast, the consumption of low-glycemic index foods results in lower but more sustained increases in blood glucose and lower insulin demands on pancreatic beta-cells.

Glycemic Load

The glycemic index compares the potential of foods containing the same amount of carbohydrate to raise blood glucose. However, the amount of carbohydrate consumed also affects blood glucose levels and insulin responses. The glycemic load (GL) of a food is calculated by multiplying the glycemic index by the amount of carbohydrate in grams provided by a food and dividing the total by 100. Dietary glycemic load is the sum of the glycemic loads for all foods consumed in the diet. The concept of glycemic load was developed by scientists to simultaneously describe the quality (glycemic index) and quantity of carbohydrate in a meal or diet.

Dog and Cat Food 

Kibbled dog and cat food is perhaps the most popular type of food fed to most companion animals.  The reasons are obvious.  It is convenient and cost effective for those who do not have the time, money, or knowledge to do a raw diet that would most closely resemble what a feline or canine would eat in the wild.  They are generally formulated so that, at the very least, they meet the minimum requirements established by AFCO (American Association Of Feed Control Officials) to provide the quantities of nutrients that are considered essential to keep an animal alive.  These minimum AFCO requirements do not in any way reflect the quality, bio-availability, or sources of these nutrients, or their effect on the overall health of the animal.   However, there are hundreds perhaps thousands to choose from and the manufacturers use clever marketing and advertising campaigns to appeal to the emotions of the pet owner and are unfortunately not always as concerned with the welfare of the animal as they would have you believe.  Many use inexpensive sources of protein and fat (such as meat of unknown or questionable origin), and fillers and binders such as grains, potatoes, tapioca, legumes etc.  These fillers are of questionable digestibility, nutrient availability, and may have a deleterious effect on the metabolic health of the animal.  These fillers are, by their very nature as plant products, high in carbohydrates and starch.  This is where the problem arises when considering the GI and GL of a particular kibbled food.

Until recently, most kibbled foods contained some type of grain product that served as both a binding material to hold the food together, and an inexpensive source of energy and nutrients.  They are not necessarily bad for the animals but they are not a main staple of a carnivores natural diet.  A new trend has developed that preys upon a common misconception that grains are a major source of allergies in dogs and to a lesser extent cats.  This is evidenced by the explosion of “grain free” foods now available.  The fact is that food allergies in dogs account for less then 10% of allergic conditions.(5-8) The marketing and advertising campaigns for these foods would have one believe that the “grain free” diets are much closer to a “wild and natural diet.”  This could not be further from the truth.  The most common replacements for the grains are potatoes and tapioca, and less often peas.  The tubers and peas are not found in the “wild diets” of carnivores.  

The idea being forwarded by the manufacturers of these foods is that your dog or cat will not suffer from allergies any longer.  Recall the incidence of food allergies is less then 10%!  The truly alarming feature of these grain replacements is that they are, in most incidences, worse for the animal in relation to their GI then the presumed problems from allergies to grains.  See the accompanying table at the end of this article for some values of the GI for various grains and “grain replacements.”  

As discussed previously, the GI of a carbohydrate source has a direct and pronounced effect on the blood sugar response to a food.  Potatoes and tapioca have a very high GI as does rice and several other carbohydrate sources.  Many are similar to feeding sugar itself!  This will effect the health of a companion animal far more then the allergy the animal is believed to experience from grains or other ingredients in the pet foods.  The high “bounce” of blood sugar and insulin response to high blood sugar is a far more serious problem then allergies that are often misdiagnosed as being caused by food stuffs!  Diabetes, obesity, pancreatitis, kidney failure, and other conditions that arise from eating high GI foods are far more deadly then the most common symptoms of allergic reactions.  The bottom line is that starch is starch, and starch is sugar!  So why not feed a starch free food?

Most raw diets are by their very nature are starch free.  Most of the commercial raw diets are either frozen or dehydrated.  However, their cost is often prohibitive to the average pet owner.  So what is the concerned pet owner to do?

Fortunately, recent technological advancements have allowed for the production of kibbled diets that contain meat percentages far greater then any seen in the past.  Many of these diets rival their raw diet counterparts.  A new line of foods developed by Wysong Corporation is actually a completely starch free kibbled canine and feline diet!  The line is called Epigen™, and is available in a 60% meat (three flavors) and 90% meat (chicken formula)!

Since a dog or cat food diet that consists of feeding the same kibbled food everyday has a relatively consistent formulation, the GL of the diet is consistent as well and can be determined using the formula above and the total values and forms of carbohydrates as provided by the manufacturer.

Glycemic Index of Selected Foods  

Food Stuff	Preparation Method	GI (Relative to Glucose)
Sweet Corn	Boiled	55 (Average)
Corn Meal	NA	55
White Rice	Boiled	82 (Average)
Brown Rice	Boiled	75 (Average)
Wheat	NA	60 (Average)
Barley (Pearled)	Boiled	25 (Average)
Oats (Rolled Uncooked)	NA	59
White Potato	Baked	111
White Potato	Boiled	78 (Average)
Tapioca	Steamed	70
Blueberries	Boiled	53
Sucrose (Table Sugar)	NA	65
Glucose	NA	100

Source: Sydney University Glycemic Index Service

General references used in preparing this manuscript:

1. Linus Pauling Institute, Oregon State University
2. Nutrient Requirements of Dogs and Cats, National Research Council, The National Academic Press 2006.
3. Encyclopedia of Canine Nutrition, Royal Canin - Source IVIS.
4. Early Nutritional Management to Reduce The Risk of Diabetes and Obesity, The IAMS Company - Source IVIS.

1. Proceedings of the North American Veterinary Conference, Orlando, FL, January 2007 - Source IVIS.
2. Proceedings of the Southern European Veterinary Conference, Barcelona, Spain, Sept. 30 - Oct. 3, 2010 - Source IVIS.
3. Personal Communication Steve Milden, VMD Delaware Valley Veterinary Hospital, Mullica Hill, NJ.
4. Whole Dog Journal Volume14, Number 4, April 2011.