TOPICS IN NUTRITION
By Geneva
Coats, R.N.
Part 1
DIET and HEALTH
Scientists have long advised
us that fresh, whole, raw foods provide greater nutritional benefits than processed foods. Eating processed foods with supplements
added does not provide the same level of nutritional benefits as eating whole foods. We also are learning that the nutrients
in whole foods work best in combination. Does this knowledge apply to feeding our dogs? Of course! We’ve probably all
been advised to avoid giving our dogs “table scraps”, “leftovers”, and “people food”.
We’ve heard that it is best to buy a commercial “complete and balanced” dog food. But where can we get advice
on how to formulate a fresh, wholesome diet? Exactly what do our dogs need to eat? How can we “balance” their
diet?
In recent years, we seem
to be noticing an increase in skin and coat problems, allergies, cancer, arthritis and other degenerative diseases in our
dogs. Is this more than a coincidence? Lifespans also seem to be getting shorter
than they were just a few generations ago, and chronic illnesses are being noted at an earlier age. Naturally, there are genetic
and environmental factors which can adversely affect health, but diet is a major factor over which we do have some control.
YOUR DOG IS A CARNIVORE
The dog’s anatomy
and physiology provide us with clues to understanding his food requirements. Over thousands of years, dogs evolved from wolves.
They became our work partners and our pets, sharing in the hunt, the resultant meals, and they also scavenged from our trash
heaps. Genetically speaking, the dog today remains nearly identical to the wolf.
In 1997, UCLA molecular biologist Robert Wayne conducted a study comparing the genes of dogs, wolves, coyotes and jackals.
He found that dogs and wolves share 99.8% of their mitochondrial DNA. Mitochondrial DNA is inherited through the tail female
line. In dogs, this genetic material goes back to a few original common ancestors. According to Wayne,
¾ of modern dogs resulted from a single female wolf lineage. Dogs
clearly originated from wolves, and have recently been classified as a subspecies of the grey wolf: Canis lupus familiaris.
Dogs have the same basic
anatomy as wolves. Both the wolf and the dog have a digestive tract that is custom-designed to efficiently process meat and
bone. They have sharp teeth designed for ripping and tearing. Molars are pointed for tearing, not flat for grinding; and the
molars mesh in a jigsaw manner, further hindering the ability to grind food. A
cow or a human can chew and grind by using a side-to-side jaw motion, but a dog physically cannot. The canine jaw opens wide,
is heavily muscled, and has a hinge design for swallowing chunks; however, the jaw cannot move side-to-side. Food remains
in a dog’s stomach for many hours, where meaty, bony meals are easily digested in an extremely acid environment. Their
intestinal tract is much shorter, smoother and more muscular than ours.
Human saliva contains amylase,
an enzyme which begins the process of digesting starchy carbohydrates. The dog’s saliva contains no digestive enzymes,
so carbohydrates must be digested entirely in the intestines. However, the dog’s intestinal tract is short, only about
one third as long as ours. Grains and other high-carbohydrate foods require a long time in the intestines to be broken down.
Ruminant animals have multi-chambered stomachs, processing and fermenting grass and grains. A dog’s short digestive
tract cannot do this. Their short muscular intestine is designed for rapid absorption of fats and amino acids. If all that
wasn’t enough, dogs do not produce the digestive enzyme cellulase, which is the enzyme needed to break down the fibrous
cell walls of plant-based foods. The dog is highly efficient at digesting proteins and fats, but less efficient digesting
plant matter such as grains, fruits and vegetables. No question about it, just
like the wolf, your dog is a carnivore!
Dogs have traditionally
survived quite handily on man’s table leftovers. However, in the early 20th century, food producers thought
of a way to change what would otherwise be waste material into profits. Using slaughter waste and grain remnants, they began
to make canned and kibbled pet food.
COMMERCIAL DOG FOOD
For thousands of years,
dogs ate raw, unprocessed, whole foods. Dogs have only been consuming processed commercial food for less than 100 years. In
that time, man has radically changed their diet. From a primarily moist, protein-based diet, with a wide range of naturally-occurring
microbes, enzymes, vitamins and full complement of amino acids; we have change their diet to a dry, carbohydrate-based food,
devoid of most natural nutrients.
Over the past decades,
the pet food industry has perpetuated these myths:
Myth #1: Commercial pet
food is complete and balanced
Myth #2: Dry food is all
your dog should ever eat.
Myth #3: It’s best
to stick with one diet and not ever change it.
Myth #4: Dogs should not
eat “table scraps” or “people food”.
Myth #5: Adding fresh foods
to a commercial diet will “unbalance” it.
Myth #6: Dry food cleans
the teeth.
Myth #7: Cooking meat is
necessary for “safety”
Regardless of how many
of our pets are sickened or killed by commercial dog food, these myths persist. Over 150 brands of commercial foods were recently
affected by manufacturer recalls due to melamine contamination. Aflatoxin poisoning in pets is also a recurrent problem, ever
since the first kibbles were invented. Toxic levels of Vitamin D and zinc have been the cause of some deaths, resulting in
more recalls. Most recently, cats in Australia
have suffered with neurologic problems resulting in death; all these cats have in common the same commercial diet. Irradiation
of this commercial kibble upon import is suspected to have resulted in dangerous vitamin deficiencies (and possibly free radical
production) causing the illnesses and deaths. The troublesome fact is that commercial dog food is not safe, and likely not
truly “complete” or “balanced”, either.
As public awareness heightens
to the dangers of commercial foods, consumer demand for safe and nutritious pet food has produced a dizzying array of choices. “Organic” “Human Grade”
and “Premium” have become buzz words. Raw diets have rightfully come into vogue, and commercially prepared raw
diets are readily available. We have come to realize that “balance” is not needed within each individual bite,
but is achieved over time. Many people have decided that home-prepared meals aren’t such a bad idea after all!
With today’s economy,
costs are an important consideration; fresh foods are often much more expensive than commercial dog foods. And, in today’s
fast-paced world, pre-packaged dog foods are convenient, and may need to be relied on as a large part of the diet. In this series, we’ll look at the basics of canine nutrition; as well as address some factors to consider
when preparing or selecting food for your dog. I hope to provide you with some inspiration for adding fresh items to the menu,
and also some practical ideas for keeping your food costs within your budget.
BASICS OF NUTRITION
Proteins, carbohydrates,
and fats are the three basic nutrients derived from food. These three major ingredients are called “Macronutrients”.
These macronutrients provide energy, while proteins also provide building material called “amino acids”. Foods
(particularly fresh, whole foods) also contain varying amounts of “micronutrients”; vitamins, minerals, antioxidants
probiotics and enzymes. There are untold thousands of different micronutrients. More are being discovered every day.
The dog’s digestive
system is not designed to process carbohydrates, so calories should be obtained primarily from protein and fat. Fiber can
also be included, although fiber is not digestible by dogs, and is non-nutritious. Fiber can, however, serve to provide some
bulk to the stool.
Water is the most important
substance in the diet; and, even though not a “food”, should always be made readily available. Filtered or purified
water may be advisable if you live in an area where the quality of the tap water is in doubt.
PROTEIN
Protein is “the staff
of life”, and should be a mainstay in the diet of the dog. Protein is necessary for tissue growth, maintenance and repair.
High dietary protein levels are necessary during periods of growth and reproduction. Studies show that high dietary protein
levels are also beneficial for older dogs. Foods high in protein include muscle meats, organ meats, fish, dairy products,
and eggs.
Proteins are made up of chains of amino acids. In the stomach, the pancreas secretes enzymes to break down these proteins into their amino acid components.
The amino acids are absorbed through the intestinal wall into the bloodstream, and then reassembled by the body into various
new proteins. Animals need specific
amino acids, not just any “protein”.
The
nutritional value of protein depends on its amino acid profile and its digestibility. There are two types of amino acids in
dietary protein:
ESSENTIAL
amino acids – must be included in the diet, and
NON-ESSENTIAL
amino acids– can be made by the body.
To
be maximally useful, a protein should contain all of the amino acids in its makeup. Lack of any essential amino acid will eventually produce illness.
Essential amino acids for
dogs include:
Arginine
Histidine
Isolueucine
Leucine
Lysine
Methionine
Phenylalanine
Trypotophan
Threonine
Valine
Taurine
(conditionally essential)
Nonessential
amino acids include:
Alanine
Asparagine
Aspartate
Carnitine
Cysteine
Glutamate
Glutamine
Glycine
Lysine
Hydroxylysine
Proline
Serine
Tyrosine
Meat,
fish, eggs and dairy products all contain high amounts of protein. Plant foods such as corn, wheat and soy also supply some
protein; however, there is a difference in the quality of protein. Animal proteins contain all the essential amino acids,
and are considered very high quality, “complete” sources of protein. Plant proteins do not contain all the essential
amino acids, so these plant proteins are considered “incomplete” proteins.
Amino acids that are often
missing in plant proteins include arginine, taurine, methionine, lysine and tryptophan. Corn does not contain any glycine,
lysine or tryptophan. Wheat is low in lysine, methionine, and threonine. Rice
is also low in lysine, but high in methionine. Lack of some essential amino acids means the protein from these plant sources
is of lower quality.
Most
of us are in the habit of checking labels to see what percent of protein that food contains. However, more important to consider
is: how much of the food's protein can be utilized once it is eaten?
The
Biological Value scale is a measurement of effectiveness for protein. Eggs are considered the “gold standard”
for complete, digestible protein. They rate 100 on the Biological Value scale, meaning that eggs are the most useful form
of protein known. By comparison, animal protein (derived from meat and organs) is rated around 80-90, while plant proteins
such as those in corn or wheat may rate as low as 40.
Every amino acid has specific
roles in metabolism. For one example let’s look at tyrosine. Tyrosine is needed for synthesis of the chemicals epinephrine,
norepinephrine, dopamine and serotonin, important neurochemicals which can affect mood. Tyrosine also aids in the production of melanin (a pigment responsible for hair
and skin color) and in making and regulating hormones produced by the adrenal, thyroid, and pituitary glands. Tyrosine can be manufactured in the body from the essential amino acid phenylalanine.
Meat sources are rich in both phenylalanine and tyrosine, so deficiency is unlikely.
Overcooking can destroy vital amino acids. Those most susceptible to heat damage
include lysine, taurine, methionine, carnitine and histidine. Shorter cooking times and lower heats will cause less damage.
Luckily, dogs have digestive tracts designed to readily and easily digest raw meat.
When reading dog food labels,
look closely at the source of protein. You want to see listed in the first few ingredients quality protein sources such as
beef, venison, pork, lamb, fish, poultry or eggs, and avoid such ingredients as unspecified “meat”, meat meal,
corn gluten, wheat gluten, rice protein or soy. Remember that the grains in the food contribute to the listed percentage of
protein content, but do not provide the complete proteins that are necessary to maintain a healthy body.
Proteins derived from grains
are not readily digestible, and can contribute to formation of allergies, bloat and gas. Cooking a protein alters its structure,
and this may also contribute to the formation of allergies. When people suffer from allergies, we sneeze and sniffle as our
bodies respond to histamine released by mast cells in our nose and upper airways. Our pets, however, have very different symptoms
when they develop an allergy. Dogs and cats have many more histamine receptors in the skin, and few in the nose. While we
may sneeze, our allergic dog will instead typically develop itchy, inflamed skin. Allergic skin problems are very commonly
seen in our companion animals. It is estimated that up to 2/3 of allergies in
dogs are related to food.
Contrary to popular belief, high levels of dietary protein do NOT cause liver
or kidney problems, nor does this cause bone or joint problems in large breed puppies. Protein restriction may sometimes be
indicated as therapeutic treatment for dogs with pre-existing liver and kidney disease. When protein is metabolized, nitrogenous
waste products are produced. Normally, the liver and/or kidneys filter out these waste products, but if these organs aren’t
working well, waste products can build up in the bloodstream, making the dog ill. A low protein diet helps to keep down the
levels of these waste products in situations where liver or kidneys are not functioning properly.
Excess amino acids can
be stripped of their nitrogen and converted into glucose. This glucose can be used immediately for energy, or can be stored
in the liver as a glycogen reserve “bank” for future energy needs.
Normally, intact proteins
cannot be absorbed. However, puppies during the first 24-48 hours after birth are able to absorb large protein antibody molecules
from the colostrum in breast milk. This allows them to temporarily enjoy the same protective immunity to diseases that their
mother has been exposed to, or was vaccinated against.
GLUTENS and melamine toxicity
Gluten is a sticky protein
substance that remains when starch is removed from cereal grains such as wheat, rye, barley and corn. Glutens are added to
pet foods as an inexpensive protein source. The protein obtained from gluten is plant protein, which lacks one or more amino
acids, and is also poorly digestable.
There are bigger problems
with gluten, however, than their low basic nutritional value. Recently, melamine was found contaminating glutens and rice
proteins sourced from China. Melamine,
a high-nitrogen chemical, was intentionally added to glutens to artificially boost their measured protein levels. Melamine,
however, can crystallize in the kidneys and cause kidney failure. This reaction was noted most particularly when melamine
was ingested in combination with cyanuric acid, another contaminant found in some glutens.
Melamine contamination
has been found in wheat gluten, rice protein product, corn gluten, and in chicken jerky. All these were sourced from China. The U.S. Food and Drug Administration has received reports of approximately 8500 animal deaths, including
at least 1950 cats and 2200 dogs who have died after eating melamine-contaminated food.
Melamine has since has been found in
milk produced in China. The latest contamination
has caused kidney stones and kidney disease in more than 50,000 human infants and caused the deaths of several human babies
when melamine found its way into infant formula.
Avoid
products which contain any sort of “gluten” or “rice protein” in their list of ingredients. Also,
avoid commercial puppy milk replacer formulas. These may be contaminated with melamine, just as human infant formulas have
been in recent months. There are several recipes out there for making your own puppy milk replacer formula using fresh ingredients…that
is a topic for another day!
“BY-PRODUCTS”
Our little wolves don’t just eat muscle meat, they eat bones and organs,
too. This helps to balance their diet. “By-products” is the term for non-muscle meat ingredients used in pet food,
such as liver, kidney, heart, and intestines. These are usually derived from healthy animals slaughtered for human consumption.
As such, they can be a very valuable source of nutrition. By-products can be
a protein source in commercial foods which is far superior to plant glutens.
It is desirable if the
manufacturer is willing to specify the exact by-product, such as “Chicken liver meal”; however, few producers
are willing to commit to the use of a specific quality ingredient. The content of by-products can vary greatly from batch
to batch. Allowable ingredients for “meat by-products” can include liver, lungs, spleen, brain, blood, bone, and
cleaned intestines. These are usually derived from cattle or swine.
Chicken by-products: “Consists of the ground, rendered, clean parts of the carcass of slaughtered
chicken, such as necks, feet, undeveloped eggs and intestines...” (AAFCO definition). Some food producers claim to only
use organ meat for their chicken by-products and not feet etc. Realistically, when many of the high-end foods are manufactured
at the same plants as the grocery store brands, can we really believe that the bulk ingredients included will be different?
RAW EGG WHITES
In the 1920's, an experimental diet in rats included large amounts of raw egg
whites. This diet produced symptoms of toxicity within a few weeks. These symptoms became known as egg-white injury
syndrome. The syndrome was caused by a lack of the B vitamin biotin. Biotin is essential for healthy hair, nails and nerves.
The major findings with this diet included severe dermatitis, loss of hair, and lack of muscular coordination. Biotin deficiency
isn't common unless you feed raw egg white, which contains a protein called avidin. Avidin blocks the absorption of biotin.
Cooking egg white inactivates avidin so that it won't pull biotin out of the
diet. Avoid feeding raw egg whites on a regular basis. Egg yolk is high in biotin, so biotin deficiency from consumption of
whole raw eggs would be unlikely.
TAURINE
Taurine is an amino
acid, found in protein foods like meat. Taurine is not generally believed to be an "essential" amino acid for dogs because
they can convert carnitine to taurine. Both carnitine and taurine, however, are destroyed by heat and processing. Some evidence
is now surfacing that cardiomyopathy in dogs may be related to taurine deficiencies. Large dogs in particular may not be able
to convert as much carnitine into taurine as they need to maintain good health.
Taurine deficiency can
result in heart failure (cardiomyopathy) and retinal degeneration leading to blindness. In the 1970s and 1980s, cats
were dying by the thousands from heart failure. The problem was determined to be a dietary deficiency of taurine. Cats in
particular must have adequate amounts of taurine in their diet, they cannot synthesize taurine as many other animals can.
Taurine is abundant in meat, fish, chicken, organ meats and shellfish. However, when cooked, a large percentage of taurine
is destroyed. It is estimated that about 50% of the taurine in meat is destroyed
by heat.
Commercial cat foods now
are all supplemented with taurine. Unfortunately, the world’s major supplier of supplemental taurine (as well as many
other vitamins and supplements) is China.
Contamination of these imported ingredients is a real concern at this point in time.
POTTENGER’S CATS
In the 1930s, Dr Francis
Pottenger conducted a feeding study on over 900 cats. He fed one group of cats a diet of raw foods including meat, bone, milk,
and fish oil. Another group of cats was fed the same diet, but the food was cooked. After observing the effects over several
generations, Pottenger found the raw-fed cats completely healthy, while those fed the cooked foods developed health problems
such as arthritis, skeletal anomalies, mouth and gum disease, thyroid problems, bladder inflammation and decline in reproductive
capability.
The reason for failure
to thrive of the cats fed the cooked diet was not understood at the time, but in retrospect it is believed that probably taurine
deficiency was one important factor involved. It took Pottenger another four generations feeding a raw diet to restore
health to the line of cats that had been previously sustained on the cooked diet.
(See the Price-Pottenger
website for more information: http://www.ppnf.org)
This raises an interesting
question: Is that health problem that you are noticing in your line due to genetics, or could it perhaps be related to dietary
deficiencies? Several generations of an improved diet consisting of fresh foods may possibly restore health and vigor to your
dogs.
CALCIUM and PHOSPHORUS
Calcium is the major mineral needed in the diet.
Along with calcium, phosphorus is needed for building healthy strong bone and teeth. Calcium and phosphorus in partnership give bones and
teeth their strength and rigidity, and are present in a 2:1 ratio in bone. Calcium in the body is also relied on for nerve conduction, blood clotting, and muscle contraction. Phosphorus represents a structural
component of cells, including soft tissue. Muscle tissue contains high levels of phosphorus.
Calcium and phosphorus
intake should be balanced in a ratio of approximately 1:1 or 2:1; in other words, between one to two parts calcium for every
part phosphorus. Phosphorus is abundant in the diet. Meats and organs are very high in phosphorus, but contain little or no
calcium. The calcium:phosphorus ratio in meat can be as high as 1:20 (1 part calcium to 20 parts phosphorus). The ratio in
some organ meats such as liver can be as high as 1:50! A diet based on just meats and organs is very high in phosphorus, and
needs to have some bone or other supplemental calcium added to provide balance.
Carnivores
like dogs and cats have a very high requirement for calcium due to the high level of phosphorus in their nearly all meat diet.
People require less calcium, if they are eating a primarily plant-based diet. Herbivores require even less calcium, and all
the calcium and phosphorus they need is contained within the plants they eat.
The need for calcium in
the diet will be even greater if the food contains large amounts of grains. Phytates (which are found in grains, nuts, and
seeds) and oxalates (found in many fruits and vegetables) bind with calcium and block absorption. Most commercial dog foods
rely heavily on grains, so they need to add more calcium to balance out their formulas.
Availability of calcium
for absorption is referred to as “bioavailability”, and is influenced by factors such as the presence of phosphorus
and Vitamin D, amount of plant matter in the diet, and by whether or not elemental calcium is released from bonds which it
has formed with carbonate, phosphate, and oxalate.
Calcium is stored in the
bones as a sort of “bank”. When blood levels of calcium drop, hormones will stimulate release of calcium from
the bones to keep blood levels of calcium where they need to be. A high phosphorus diet will draw calcium from the bones, because phosphorus has a high affinity
for calcium. Over time, this can result in bone weakness, deformities and fractures. The same happens in humans. A diet of
hamburger and soda pop is very high in phosphorus, but lacks calcium. Osteoporosis can be the end result.
Dogs who have some raw
meaty bones included in their diet will get enough calcium, in an optimal ratio. This is logical since they are approximating
their natural diet. Soft raw bones such as ribs, backs and necks are preferable to the harder, weight-bearing bones such as
leg and thigh bones. Bones should never be served cooked as they become brittle when cooked and may splinter.
Some people have safety
concerns about serving raw bones, and choose to omit them from the diet entirely. If you are feeding meat (either raw or cooked)
without any bone, calcium should be added to the diet in the form of a calcium supplement, bone meal, or ground eggshells.
Add ½ tsp ground eggshells, or 1000 mg supplemental calcium, or 1-1/2 tsp bone meal per pound of food. This will provide the
proper calcium/phosphorus ratio. If you add grains to the diet you will need to add a bit more calcium. If bones are not included
in the diet, you will need to add some vegetables or fruits to the diet. This will provide some bulk to help maintain firm
stools.
Calcium supplements such
as calcium lactate, calcium citrate or calcium carbonate can be used. “Tums” brand is a calcium product; it contains
primarily calcium carbonate derived from limestone. It is intended for use as an antacid but can be used as a source of calcium.
Tums does not contain aluminum as other antacids do; however, Tums may contain other undesirable ingredients such as sugar,
starches, herbs and flavors.
Dairy products including
cheese and yogurt can be a way to include calcium, and these foods also include some vitamin D, which enhances absorption
and metabolism of calcium. Ricotta cheese, hard cheeses, yogurt and evaporated milk are all good sources of calcium. Cottage
cheese is much lower in calcium than most other dairy products, and is also high in sodium and phosphorus. Some dogs, like
some humans, can have difficulty digesting milk products.
What about bone meal? Ground eggshells contain 98% pure calcium carbonate, while bone meal contains calcium, phosphorus,
magnesium and other trace minerals. Bone meal contains two parts calcium to one part phosphorus. When using bone meal, you
are not just adding calcium, but you are also adding more phosphorus to the diet as well. So, you will need to add to food
a larger amount of bone meal than you would ground eggshells. Instead of ½ tsp of eggshell per pound of food, you would need
to add about 1-1/2 tsp bone meal. Research in the 1980s found that many bone meal preparations were contaminated with lead
and other toxic metals. Look for a high-quality bone meal intended for human consumption.
Do not add calcium to commercial
diets that advertise as being ”balanced”, since they already include calcium and phosphorus in their proper ratio.
If you are feeding raw meaty bones on a daily basis, you do not need to add any supplemental calcium.
Overuse of calcium may
cause magnesium deficiency and constipation. Too much calcium also inhibits zinc, copper and iodine absorption. Excess calcium
in the diet is not absorbed from the intestines, and is excreted in the feces. The exception to this is young puppies under
six months old. There are indications that overfeeding calcium to large breed puppies may have an adverse effect on bone growth
and development.
Excessive calcium intake
during pregnancy may cause problems. The parathyroid gland responds to low blood calcium levels, and releases a hormone to
stimulate calcium release from bones. This maintains calcium balance in the bloodstream. The prevailing theory is that if
you are feeding a steady supply of calcium to the mother, her bloodstream maintains constant levels of calcium. The parathyroid
gland then becomes inactive, since it is not needed. Later, when parathyroid hormone is needed to manage calcium levels during
birth and lactation, the gland may become “lazy” and not work as well as it should. Dangerous low blood calcium
levels can occur. The end result could be the need for a c-section, as the uterus may not contract well due to low blood calcium
levels. Another life-threatening problem from low calcium is eclampsia, a condition where the dam has seizures. Once the puppies
are born, plenty of calcium should be added to the bitch’s diet, but prior to birth do not fall into the habit of including
excessive amounts of calcium in her diet.
Vitamin D is necessary
in the diet for proper calcium metabolism. Vitamin D is needed to absorb calcium, to regulate blood levels of calcium and
to enable bone mineralization. Fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Vitamin
D is also found in beef liver, cheese, and egg yolks. Vitamin C in the diet will also enhance calcium absorption.
Cod liver oil contains
both vitamins A and D, but don’t overdo it! These fat-soluble vitamins are stored by the body and can be toxic in large
amounts. Nutri-Cal and Nutri-Stat both contain substantial amounts of cod liver oil, so please use those products sparingly.
When fed to the bitch during early pregnancy, too much of these vitamins can cause birth defects.
In Part Two, we will cover
fats, fatty acids, fish and fish oils, and Vitamin E. See you next issue!
