By Gael Goldsack. Dip. Med. Tech., C. Biol. MIBiol.
Dogs, like their ancestor, the wolf, are classified as carnivores. Wild dogs are traditionally hunters, scavengers, opportunists and omnivores rather than true carnivores as their classification suggests. They are hunters, meaning they hunt and kill small game such as small mammals or birds. They are also scavengers that eat carrion and opportunists meaning they eat some vegetable matter such as berries.
When the dogs dine on their catch or find, they will devour the whole animal including the skin, bone, hair feathers and the contents of the animal’s gut. Dogs can easily digest the flesh and bones of their prey and the partly digested stomach contents. Dogs also eat fruits and other vegetable matter, but are unable to digest the cellulose plant fibres as their short gut is used to digestion of meat.
Domesticated dogs have the same short gut as their wild ancestors; therefore their diet should be similar. They need a high quality protein source, some fat, bone and roughage.
For normal growth and maintenance of condition all dogs require a balanced diet of the following elements:
Protein – obtained from lean meat, fish, eggs, cottage cheese, etc. Good quality protein should form 25% of a balanced canine diet. A dog’s ability to digest protein is variable. Protein from fresh (uncooked) meat sources is 90-95% digestible, whereas protein from vegetable sources is only 60-80% digestible. Protein is required to build body tissues. A deficiency will result in muscle wastage.
Carbohydrates – obtained from raw vegetables, grains, etc. Dogs require glucose, which is derived from the digestion of more complex carbohydrates. The glucose supplies energy for body function. A glucose deficiency may result in dull unresponsive dogs and may lead to mental unsoundness.
Fats (more specifically, omega 3 and omega 6 fatty acids) – obtained from pork or chicken fat, raw egg yolks and some vegetable oils. Fats should comprise 5-20% of balanced diet. They are efficiently digested in dogs.
Fats are required for healthy skin and coat growth so a fatty acid deficiency may result in dry itchy skin and coarse hair.
Minerals – obtained from raw bones. Never feed cooked bones! There are two mineral groups required by dogs: the “Macro” minerals, such as calcium, phosphorus, sodium, potassium and magnesium, are required in milligram quantities an a balanced diet and the “Micro” minerals, such as iron, copper, zinc, manganese and iodine, are required in microgram quantities in a balanced diet. Minerals are required for healthy bone growth so a mineral deficiency may result in poor or deformed bone growth.
Of all the minerals, calcium and phosphorus are the most important to dogs. A calcium to phosphorus ratio of 1.2 – 1.4 to 1 by weight is required in a balanced canine diet. The presence of vitamin D is required to facilitate calcium and phosphorus absorption. If the calcium to phosphorus ratio is correct, but there is no vitamin D in the diet, a calcium and phosphorus deficiency develops. If vitamin D is fed in excess, not only are the calcium and phosphorus absorbed from the diet into the blood stream but also from the bones. The calcium is then deposited elsewhere, in organs such as in the kidneys, with sometimes fatal results. An all meat diet is very low in calcium (raw meat contains 2.6% phosphorus) giving a calcium to phosphorus ratio of 1:20
Vitamins – Dogs require thirteen major vitamins; the best know are vitamins A, D, E, K, B1, B2, B6, and B12.
Fibre is obtained from vegetable pulp, grains, etc.
As in humans, dogs require some fibre in their diets to ensure a healthy digestive system.
Water – Over 90% of a dog’s body mass is water. Fresh water should be available to your dog at all times.
A balanced diet of the above elements should be fed to ensure good heath, growth and reproduction. A balanced diet is one that contains the above elements in the correct proportions. An unbalanced diet may lead to health problems including obesity, diseases of the gums and the inability to breed and reproduce.
Dog food manufacturers go to extraordinary lengths to formulate, manufacture and market their products. Complete dog foods, such as those available in dry, semi-moist and canned varieties, have been formulated by the pet food industry to provide a balanced diet for your dog. A commercial diet will suffice, that is your dog will theoretically receive the correct nutrition, but may suffer from diseases of the teeth and gums (such as periodontal disease), skin diseases, obesity or reproductive problems without supplementation with additional fresh food.
Complete dry dog food contains approximately 10% water, an excess of cereal products, may be deficient in essential fatty acids and could contain low quality protein. Dogs fed on an exclusively dry diet may be prone to skin diseases.
Semi-moist dog food contains 30% approximately water and may be high in carbohydrates. Dogs fed on an exclusively semi-moist diet may be prone to obesity.
Canned dog food contains 80% approximately water. It contains less cereal and more animal tissue than dry food, but may contain a high proportion of vegetable protein (usually soy – an allergen in some dogs). It is on the whole more digestible than dry food. Dogs fed on an exclusively canned diet may be prone to diseases of the gums, bad breath, etc.
All commercial dog foods are high in soluble carbohydrates and salt. This may lead to heart disease or tartar formation and subsequent periodontal disease.
So, what are the alternatives?
The home made “stew” is a poor replacement for a commercial diet. It generally contains cooked meat, vegetables and grains. That is similar ingredients to commercial dog foods, and consequently may cause similar problems.
An all meat diet is high in protein and consequently high in phosphorus and low in calcium, iodine, copper, vitamins A and E.
Table scraps usually lack protein, are high in carbohydrate and fat and may contain cooked bones.
BARF diets are becoming increasingly popular amongst Australian dog owners. BARF stands for Bones And Raw Food or Biologically Appropriate Raw Food. Two notable examples of these diets are those advocated by Billinghurst and Pitcairn. They are based on the theory that 40 years ago, when commercial dog food was not available, most pet dogs were fed on fresh bones and leftovers. Consequently, most dogs were healthy, with no growth or reproductive problems, few skin diseases and very little arthritis or cancer.
Dr Ian Billinghurst is an Australian veterinary surgeon who has written several books on the subject. The Billinghurst Diet is based on raw meaty bones that comprise 60% of the dog’s diet. He says that dogs should be fed on as wide a variety of food as possible – bones, meat, vegetables, fruits, dairy products, eggs, seafood, grains, pulses, brewers yeast, kelp powder, etc. It is important to balance the dog’s diet over many meals, not every meal.
While there may be reasons for cooking some food; to kill germs and the toxins they produce, to kill parasites, to enable storage and transport etc., the emphasis is on raw food as cooking destroys vitamins, enzymes, and anti-oxidants and reduces protein availability.
Basically, these BARF diets make available all the elements required for good nutrition. To make some elements, such as those available in fresh vegetables and fruit, available to the dog the vegetables must be pulverised (in a blender), as dogs are unable to digest cellulose. Fruit should be fed very ripe, but not rotten.
It is important when feeding your dog that he doesn’t get overweight. Regardless of what diet you feed your dog or puppy, you should let his waistline be the guide. You won’t be able to easily feel the ribs on a fat dog or puppy and he will not have a “waistline”. Obesity in dogs, as in humans, can lead to heart disease and other health problems.
There is much discussion on the best feeding regime for puppies and dogs. Generally, puppies from 8 to 16 weeks of age need 3 meals per day. This can be dropped to two meals per day until he reaches 9 months of age, then one meal per day. You may want to continue with two meals per day for the rest of your dog’s life, especially if it is a large deep-chested breed that may be prone to bloat. Bloat is a life-threatening condition in some breeds (eg Dobermans, Weimeraners, Great Danes, Rottweillers, most of the large sighthounds etc.) where the stomach fills with gas. If not treated immediately, the stomach may torsion and the dog will quickly go into shock
and die. Dogs prone to bloat should be fed two smaller meals each day instead of one large one and not exercised for at least an hour before or after eating.