Vitamins

Dogs need vitamins. They are  critical for growth and  maintenance of good health. A diet lacking in a vitamin can produce a variety of nasty symptoms. On the other hand, too much of a vitamin will produce other symptoms.

Vitamins are divided into two groups: fat-soluble and water-soluble. The fat-soluble vitamins are A, D, E and K. The water-soluble vitamins include B12, biotin, C, choline, folic acid, niacin, pantothenic acid, pyridoxine (B6), riboflavin (B2), thiamine (B1), and B12.

Vitamins occur naturally in food, and can be purified into a crystalline powder. In the manufacture of most dog foods, the processing method destroys some vitamins. These are added back so the final product has a balanced amount of the necessary vitamins.

Fat-soluble vitamins are absorbed in the intestine just like any other dietary fat. These vitamins are then stored in fatty tissues. Most animals have enough of a reserve to carry them through times of deprivation.

Water-soluble vitamins are not stored in the body. Water, passing through the body daily, carries these vitamins away. They must be replaced every day.

Vitamin A is necessary for the production of visual pigment found in the retina’s rod cells. It also is important for bone growth and reproduction functions, and maintenance of epithelial tissue such as skin and the respiratory, urogenital and digestive tracts.
Young dogs are more susceptible to vitamin A deficiency than adult dogs. They have less storage space, and have not had the time to build up reserves.

Some vitamin A deficiency symptoms include stunted growth, loss of weight and appetite, night blindness, reproductive failure, a nervous incoordination (staggering walk), and xerophthalmia, which is an eye disease. Too much vitamin A has been associated with irregular and defective bone growth.

Vitamin D is critical to the dog’s ability to use calcium and phosphorus. These two minerals are required for bones and cartilage to develop properly. Without adequate vitamin D, the young will develop rickets, and adults will develop osteomalacia – two types of bone deformities.

Vitamin E is an antioxidant. It protects the cell membranes throughout the body from oxidative damage, which changes the nature of the cell. Vitamin E keeps muscles from degenerating and maintains proper reproductive performance. Vitamin E must be properly balanced with the mineral selenium.
Vitamin K is essential for normal blood coagulation and clotting. Deficiencies show up as bleeding that doesn’t stop.

The water-soluble vitamins are not stored and are washed out of the body every day. A deficiency is more likely than a toxicity.

Thiamin (vitamin B1) promotes a good appetite and normal growth. It is required for basic carbohydrate metabolism and thus, energy production. Deficiency of thiamin is rare, and is usually caused by an anti-thiamine factor in the diet. A deficiency will show up as anorexia or cardiovascular disturbances.

Riboflavin (vitamin B2) promotes growth and is involved in several enzyme systems. It’s also important in carbohydrate and amino acid metabolism. Puppies need more riboflavin than adult dogs. Deficiency symptoms may include weight loss and dry, flaky skin.

Pyridoxine (vitamin B6) is import-ant to nitrogen metabolism and red blood cell formation. Deficiencies show up as anorexia and poor growth. In severe cases, convulsions may occur.

Pantothenic acid is required for energy metabolism. It is a component of coenzyme A, a carrier protein in the process of metabolizing protein. Slow growth and loss of hair may be signs of a deficiency.

Niacin is a constituent of many coenzymes which help cells process carbohydrates, proteins and fats. A niacin deficiency in dogs shows up as a darkening of the tongue called Black Tongue Disease.

Vitamin B12 is a coenzyme necessary for normal DNA synthesis. It’s important for proper folic acid metabolism, so a deficiency in one can lead to a deficiency in the other. Slow or retarded growth is the main symptom of a deficiency. Pernicious anemia, where vitamin B12 is not absorbed properly in the intestine, results in a deficiency.

Folic acid is related to B12 metabolism and a variety of other bodily biochemical reactions. Slow growth and poor appetite are also symptoms of folic acid deficiency.

Biotin is a component of several enzyme systems. Symptoms of deficiency are nonspecific, but dermatitis is one which is sometimes seen.

Choline is involved in proper trans-mission of nerve impulses. It is also a component of certain fats.

Vitamin C is not required in the diet of dogs, as their body can synthesize it. People cannot do this. Vitamin C participates in a number of body development functions such as the formation of intracellular substances of the teeth, bone and soft tissue. Scurvy is the classical symptom of vitamin C deficiency in man. It is swollen and bleeding gums with a loosening of the teeth.

It’s not usually necessary to give your dog a vitamin pill. Most animals get all of the vitamins they need from a good, commercially produced diet.

Sugar: Is It Bad For Your Dog … Or Really Good?

Sugar comes in many forms. What we commonly think of as sugar, that white stuff, is refined sucrose. It comes from sugar beets. But there are many other kinds of sugar. Milk contains lactose, fruits contain fructose, and there’s dextrose from plants.

It comes from sugar beets. But there are many other kinds of sugar. Milk contains lactose, fruits contain fructose, and there’s dextrose from plants.

In dog treats and foods, you’ll find ingredients such as sugar (sucrose), brown sugar, dextrose, corn syrup (which is high in fructose), malto dextrins (a sweetener derived from corn starch), and molasses, which is actually a by-product of the sugar-making process.

All of these added sugars are used as sweeteners, to make a food taste better to your dog. They enter the bloodstream quickly, and can give your dog a fast energy boost. The protein and carbohydrates in the food are also being digested, and converted by the body into … sugar.

That’s right, one of the main purposes of eating is to supply the body with energy in the form of sugar. Glucose is the sugar the body makes from food.

Glucose is an incredibly important sugar, as it is the only nutrient which can cross the blood/brain barrier, a membrane which protects the brain. Glucose is brain food, the single nutrient that keeps gray matter humming. Because supplying energy to the brain is the single most important function for the rest of the body, glucose production takes priority over nearly every other activity. Also, most foods will end up being converted to glucose to supply the brain with power.

How does your dog’s body turn food into glucose? You could say the digestive process actually begins when a food is digested. To help with the digestive process, grains are milled, which breaks open the protective coat and exposes the nutrients inside. Cooking breaks down complex molecules into more readily accessible ones

Next, saliva and chewing continue the process, changing some starches into simple sugars. In the stomach, the acid environment breaks down the entire meal into its individual components – the nutrients. Carbohydrates break into starches and sugars. Proteins are broken into amino acids. Fats become fatty acids.

Next, at the small intestine, these nutrients are absorbed, and the bloodstream takes them to the tissues where they’re needed. At the tissue level, the nutrients are used for building tissue, repair work, or storage. The bloodstream also carries glucose to the brain for its critical work.

Amino acids, carbohydrates and fatty acids each have their own digestive or metabolic process. All are regulated by hormones.

Let’s take a look at each part of the food to see what happens to it.

Protein is made of amino acids. There are 22 amino acids. Most are supplied by the food. The essential amino acids must be included in the diet while others can be manufactured by the body from various building blocks. Insulin, a hormone made by the pancreas, helps transport the amino acid across each cell’s membrane and into the tissues. Once there, the cells put the amino acids to work.

Some of the protein’s amino acids are converted into energy in the form of glucose. Protein provides 5.65 kilocalories of gross energy per gram.

Carbohydrates can be used for energy, too. This frees up the protein’s amino acids for use in building tissues. When carbohydrates are converted into energy, they, too, produce glucose, along with other products.

Cereal grains, such as corn, wheat and barley, contain carbohydrates in the forms of sugar and starch. These, in turn, get broken down through digestion to make glucose. About 80% of the grains are starch, and there is a small portion which is sugar. The rest of the grain, between 2% and 15%, is what we call crude fiber – cellulose and hemicellulose. By comparison, green vegetables are about 20% sugar, 1% to 5% starch, and 10% to 20% fiber.

The main way your dog produces glucose is by digesting carbohydrates into starches and sugars. Starch provides 4.23 kilocalories (thousand calories) gross energy per gram, and just for reference, glucose itself provides 3.76 kcal of gross energy per gram and sucrose 3.96 kcal.

Fat has 9.45 kcal of gross energy per gram, but unfortunately, fat gets deposited in fatty tissue instead of being used for glucose production. Your brain wouldn’t  mind your being on a fat-free diet to lose weight, as long as it gets its glucose from somewhere. Fasting causes the body to use its fat stores for work, but it doesn’t supply the brain with glucose. That’s why people who fast drink juice – a source of fructose, which converts readily to glucose.

Is it bad for your dog … or really good?

Insulin plays a big part in all of this. It’s a hormone which stimulates amino acids to be transported into the cell membranes of muscle, the liver, and fat tissues. It helps the body rebuild amino acids into new proteins. (If the pancreas is not putting out enough insulin, diabetes results.)

Immediately after a meal, the glucose absorbed into the blood causes the rapid secretion of insulin. The insulin, in turn, causes the rapid uptake, storage and use of glucose by almost all tissues of the body, but especially by the liver, muscle and fat.

Insulin also promotes the conversion of glucose in the liver into fatty acids. Those not used are transported to adipose tissue (fat tissue), and deposited as fat.

Finally, let’s look at glucose and the muscles. During most of the day, muscles depend not on glucose but on glycogen, a stored form of glucose, for their energy.

The main reason why the normal, resting muscle doesn’t use glucose is that it is impermeable to glucose except when insulin is present. The muscle will only use glucose during heavy exercise, and in the few hours immediately after a meal.

After a meal, the blood glucose levels are high, as are the levels of insulin. This causes rapid transport of glucose into the muscle. Some dogs (and people) get a burst of energy an hour or so after a meal, and run around like nuts. That’s because all of the glucose goes straight into the muscle, where it is preferred over glycogen. If there’s no exercise going on, the muscles will take the glucose in and store it as glycogen.

A final note about glucose. You know how you feel good after you eat? That’s because glucose is feeding your brain, and your brain is extremely happy. There’s a release of endorphins, which make you feel good, and relax you. That’s why after a big meal you feel tired, and you’re ready for your nap. A few hours later, you’ll be raring to go.

So, what have you learned? That the body takes much of your food and converts it to glucose. That glucose is the only nutrient which can feed the brain. That carbohydrates provide a steady stream of glucose, freeing up the amino acids in proteins to work on building and repairing cells, not on producing glucose.

Sugar is an important part of the body’s functioning. It’s a natural outcome of the digestion of protein, starches and carbohydrates. There’s just no need for it to be added to your dog’s diet, except to make it taste better.

Carbohydrates and Crude Fiber

Understanding carbohydrates  and fiber sources is important  to understanding dog food labels and selecting the food which is right for your dog.

Nutrition means many things to many people. The truth is, though, nutrition is the process of assimilating food for the biochemical processes of life.

In this section, we’ll take a look at the energy (carbohydrate) and fiber components of several common ingredients of dog food. Which ingredients provide energy? Which provide fiber? Why are these facts important?

Nutritional Needs

The nutritional needs of your dog vary depending on his stage of life and amount of activity. Dogs who are growing puppies or adolescents, pregnant females and nursing mothers all need more energy than adult dogs. Behavior and amount of work also play an important role in deter-mining the nutritional needs of your dog. An active dog requires more energy than a sleepy, old dog.

Eating food is the way the body’s nutritional needs are met. Food consists of ingredients which the dog breaks down through the digestive process.

Each ingredient supplies a number of nutrients, which are released through digestion. The nutrients are utilized by the body, while the portions not digested are excreted as urine and feces.

What makes a food ingredient high quality or low? That depends on how much of each kind of nutrient is readily available for use by the dog. Nutrients are carbohydrates, fats, proteins, minerals, vitamins and water. Energy, although not considered a nutrient, is an important nutritional requirement. The nutrient profiles – how much of each nutrient is available from a given ingredient – are shown in the chart in an abbreviated version.

Energy

Carbohydrates, proteins and fats all supply the dog with energy. Fat supplies twice as much energy per gram as carbohydrates when digested.

Energy results from metabolizing carbohydrates, proteins and fats. Every movement and activity of the dog’s life involves the expenditure of energy, which is the body’s fuel supply. The dog needs fuel for breathing, eating, muscular movement and maintaining a constant body temperature. The amount of energy your dog requires is influenced by his metabolic rate, his age, stage of growth, activity level and the climate he lives in.

A dog living in a cold climate may need 80% more calories of energy than a similar dog in a hot climate. Dogs involved in hunting, herding or racing may require 100% to 300% more calories per day than the average house dog.

Energy is expressed in terms of calories. It is common to express the caloric content of dog food in terms of kilocalories per pound or kilocalories per cup. One kilocalorie equals 1000 calories.

Carbohydrates vs. Crude Fiber

Carbohydrates and fiber are abundant in plants and occur in a variety of forms. The digestible carbohydrate (nitrogen-free extract, or NFE) portion of the plant is in the form of starches and sugars. The non-digestible portion of the plant (crude fiber, or CF) is composed of cell walls, cellulose and lignin.

Adult maintenance, puppy and performance dry dog foods contain 3% to 6% crude fiber. Weight-reducing diets and light varieties of dry dog food contain 8% to 25% crude fiber. Nearly all (95%) of the crude fiber figure is cellulose. Cellulose is not digestible by dogs because they lack the enzymes necessary to break it down and utilize it.

Low Fiber vs. High Fiber Diets

A small amount of crude fiber is needed to promote good muscle tone and activity in the dog’s digestive tract. Too little fiber in the diet will cause a dog’s stool to become loose.

Dog food with a high fiber content passes rapidly through the dog’s system. Digestion is less efficient since the food doesn’t have enough time to be exposed to all of the digestive enzymes. Too much fiber (cellulose) in the diet can cause a dog to have hard, compacted stools.

Weight-Reducing Diets

There are two ways to decrease the caloric content of a diet. One is to simply decrease the amount of fat in the food. The other is to increase the fiber content of the food. For example, when fiber sources such as peanut hulls, rice hulls or oat hulls are added to a dog food formula, the overall nutrient (caloric) density of the diet decreases. The increase in fiber (bulk) causes the dog to consume less food. Since his stomach is filled faster with the bulky (fibrous) food, the dog takes in fewer calories. This is the idea behind some weight-reducing diets.

Carbohydrate and Fiber Sources

Beet Pulp

Many people think that beet pulp is added to a dog food as a source of fiber. While this is true, beet pulp is also a carbohydrate. Look at the chart to compare both fiber sources and carbohydrate sources.

Most dogs get their energy from the carbohydrates available in cereal grains such as wheat, corn or oats. Unfortunately, these have very little fiber. Beet pulp, on the other hand, gives your dog the fiber he needs as well as carbohydrates. Other benefits of adding beet pulp to a dog food include promoting muscle tone in the digestive tract and good stool quality.

There is nothing wrong in using beet pulp – in fact, it’s really a “good guy” ingredient. Contrary to some reports, it doesn’t turn a dog’s coat red – beet pulp is grayish white in color. Beet pulp is a great fiber source which will keep your dog’s intestines healthy.

Sources: Maynard, L.A. & J.K. Loosi, Animal Nutrition, 7th Edition, McGraw-Hill Book Co. Inc. 1979.
Ensminger, M.E. & C.G. Olentine, Feeds & Nutrition, 2nd Edition, Ensminger Publishing Co., CA 1990.