When it comes to food, nutrients are what really matter

Formulating a balanced food for dogs is a complicated task. Dogs have to take in around fifty nutrients through their food, in the appropriate proportions. These nutrients all have to fit together like jigsaw pieces, which demands knowledge of their complementary nature.

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Like all animals, dogs are made up of tens of millions of cells, each of which produces the energy and the building blocks the body needs. The mitochondrion of each cell is a mini power plant, which runs on fuel provided in the diet and oxygen provided through respiration, conveyed by red blood cells. When this system works properly, the dog’s temperature is maintained at a constant level and the body is able to continuously rebuild and repair itself.

Without a good understanding of the roles of nutrition, including all the exchanges between the body and the exterior environment, it will not be possible to provide the dog with all the nutrients it needs.

A guide to these essential nutrients follows.

CARBOHYDRATES

Carbohydrates is a term that covers molecules composed of carbon, oxygen and hydrogen that have certain chemical characteristics in common. Carbohydrates are predominantly vegetable, with the exception of blood glucose, glycogen in the muscles and the liver, and milk lactose.

All vegetables contain carbohydrates, ranging from saccharose in beet to the most indigestible fibre in tree bark.

Dogs can live without carbohydrates in their food, as they synthesise the carbohydrate they need for the cells from amino acids. The intake of carbohydrates does however greatly improve the body’s functioning.

While glucose, saccharose, lactose and starch have the sole function of furnishing energy, their botanical origin and how well they are cooked influence their digestion.

The presence in the food of poorly cooked starch can cause diarrhoea. Fibre, which is also a carbohydrate, is very good for transit and for the balance of bacterial flora. This is true of fructo-oligosaccharides (FOS) and mannan-oligosaccharides (MOS) for instance.

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Starches

Health and prevention

To be digested by dogs, starch must be very well cooked or it will ferment in the large intestine and cause diarrhoea. Too much starch can have the same result if the amount ingested exceeds the animal’s enzymatic digestive capacity (in Nordic dogs for instance).

A little background information

Starches are carbohydrate molecules in which thousands of glucose molecules are linked together by simple chemicals bonds.

Its role in the body

Starches are used only to provide energy to the
animal, after being degraded by the digestive process to help the intestine gradually absorb the glucose molecules.

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Sugars

also known as: Simple carbohydrates, Di- and Tri-saccharides

Health and prevention

Sugars have no preventive or curative functions in dogs. But, when in excess in the food, they can lead to obesity and in some cases the development of diabetes.

A little background information

In everyday language, when we talk about sugar, we refer to the sweetening power and taste of carbohydrates like saccharose (sucrose) or fructose. With no qualifier, this term usually refers to saccharose (beet or cane sugar), but it could just as well refer to glucose (grape sugar), fructose (fruit sugar) or lactose (milk sugar).

Its role in the body

While lactose provides immediate energy to unweaned puppies, a digestive enzyme, lactase, is necessary to make it biologically available; lactase disappears once the animal stops feeding on milk. Since later on dogs cannot taste “sweet” things and since they can synthesise their own blood glucose from proteins autonomously, sugars have no nutritional value for them.

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Cellulose

also known as: Total dietary fibre (TDF)

Health and prevention

Thanks to recent advances in scientific knowledge on the raw fibre components of food,
diseases like obesity, diabetes, constipation or diarrhoea can be prevented or cured more effectively by adding these components in the right quality and amount to an animal’s diet.

A little background information

Cellulose is a very large molecule consisting of thousands of glucose units linked together by stronger chemical bonds than those found in starch. But cellulose represents only part of the total fibre in food. The term includes other soluble or insoluble fibrous plant substances, such as hemicelluloses, pectin, lignin and oligosaccharide fibres. On its own, cellulose does not have much of a nutritional effect, despite the raw cellulose content being stated on labels.

Its role in the body

The role of fibres in the body is dependent on their nature. Indigestible and insoluble fibres (pure cellulose, lignin) act as ballast in the bowels, helping them to function mechanically by stimulating contraction (peristalsis). Soluble fibres can be important for the health and hygiene of the digestive tract (FOS, MOS). The intake of sufficient fibre is important to produce a feeling of satiety in animals at risk of becoming overweight.

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FOS

also known as: Fructo-oligosaccharides, Prebiotics

Health and prevention

The addition of FOS to a food prevents infectious diarrhoea caused by the proliferation of dangerous bacteria in the intestine, while providing adequate nourishment to intestinal cells to facilitate their regular regeneration.

A little background information

Fructo-oligosaccharides (FOS) are fermentable fibres. They are not digested, but are nevertheless rapidly fermented by the bacteria in the colon, resulting in the release of small-sized fatty acids (known as volatile fatty acids) that:
- acidify the intestinal medium;
- are excellent nutrients for cell maintenance and renewal;
- line the walls of the large intestine.

Its role in the body

Through fermentation, FOS are a direct source of nourishment for the cells of the large intestine. But they particularly promote the growth of specific bacterial flora (bifidus and lactobacillus) that have well-known beneficial effects on the health of the digestive tract:
- they inhibit the development of pathogenic bacteria;
- they improve digestion and nutrient absorption.
FOS supplementation in the food of bitches used for breeding helps increase the antibody count (IgM) in the milk, which promotes good immunity in the puppies.

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MOS

also known as: Mannan-oligosaccharides

Health and prevention

MOS contribute to an adequately balanced bacterial population in the bowels, and have a direct and indirect effect on the health of the digestive tract. Thus, they are very effective in preventing diarrhoea and contribute to the prevention of digestion-related infectious diseases.

A little background information

Mannan-oligosaccharides belong to the large category of fibre, which means they are non-digestible carbohydrates. Just like FOS, they are effective against harmful bacteria living in the intestinal lumen, but have a different mode of action. They are composed of two sugars: glucose and mannose.

Its role in the body

These yeast fibres are beneficial to the digestive tract by acting in two ways:
- they prevent the development of pathogenic bacteria by stopping them from attaching themselves to the intestinal mucosa;
- they directly enhance the effectiveness of the body’s immune system, helping the body resist pathogenic agents.

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Mucilage

Example: psyllium fibre

Health and prevention

Mucilage is the soluble fibre used to treat problems of digestive transit. It regulates transit and facilitates faecal elimination.

A little background information

Psyllium grains are a very good source of mucilage. Psyllium comes from the Greek “psyllia”, which means flea. The grains, black or golden depending on the species, resemble tiny psyllids. Psyllium is very commonly used in the food of sled dogs, to prevent stress diarrhoea.

Its role in the body

The mucilage that makes up the exterior layer of psyllium grains has a large water retaining capacity. It puffs up by capturing water and creating a gel that increases the viscosity of the contents of the intestine (chyme). Psyllium improves digestive transit.
It therefore combats constipation, which is its main indication in human medicine. The advancement of faecal matter through the colon is more regular and the lubrication induced by psyllium facilitates faecal elimination.

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LIPIDS

Dogs are naturally attracted to foods rich in lipids, but they must be limited when the animal does not get a lot of physical exercise.

In the absence of very strict rationing an excess intake of lipids leads to obesity, but animals cannot do without them, as they provide energy and essential fatty acids.

Lipids constitute a family of organic substances more commonly known as fats. Fatty acids and glycerol, which together form the triglycerides, are the main elements. Lipids may be simple (triglycerides, waxes) or complex (containing many other elements). Cell membranes for example are composed of phospholipids.

Fats are the benchmark energy source for dogs, which oxidise them to extract the energy they need. A gram of lipids represents approximately 9 kcal of metabolisable energy, two and a half times more than that provided by a gram of carbohydrates or proteins.

Some fatty acids – termed essential – also have structural roles for the cell or act as precursors to specific hormones.

Dietary lipid sources are all foods rich in animal fats (butter, tallow, lard, eggs, poultry fat, fish oil) and vegetable fats (oils, oilseeds).

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Fatty acids

Health and prevention

Polyunsaturated fatty acids, which are abundant in dietary oils, are degraded by oxygen, heat and light. This phenomenon of rancidity may become dangerous due to the formation of complex compounds (hydroperoxides). This is why the addition of antioxidants to food is indispensable.

A little background information

Fatty acids are the main constituents of lipids. They are characterised by the number of carbon atoms they possess, hence the expressions short-, medium- or long-chain fatty acids. They can be saturated (no double chemical bond between 2 carbons) or unsaturated (with 1 to 6 double bonds). Though the latter, more fragile, are subject to rancidity, they include many fatty acids that are essential to vital functions.

Its role in the body

Saturated fatty acids are exclusively energy sources (referred to as “empty” calories since they play no other role). Short-chain saturated fatty acids (6-10 carbon atoms) are a very good source of fast energy for sports dogs, diabetic animals and newborn puppies. The function of polyunsaturated fatty acids is structural (in membranes or in blood lipoproteins); they include the omega 3 and omega 6 chemical series that have vital functions and cannot be synthesised by the body.

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Omega 6 fatty acids

Health and prevention

The intake of linoleic acid is indispensable to the synthesis of cell membranes. Deficiency provokes the appearance of dry, brittle and thin hair. It also affects the integrity of the skin barrier: the skin becomes more sensitive to dehydration and infection.

A little background information

The omega 6 series of fatty acids are biologically indispensable fatty acids that are derived from an essential fatty acid containing 18 carbon atoms and two chemical double links, known as linoleic acid. Two other long-chain fatty acids are derived from linoleic acid: gamma-linolenic acid (GLA) and arachidonic acid.

Its role in the body

Indispensable to the synthesis of prostaglandins, hormonally active molecules, omega 6 fatty acids have a positive effect on the health of the skin and the quality of the hair, as well as the animal’s reproductive system.

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Gamma-linolenic acid

also known as: GLA

Health and prevention

Gamma-linolenic acid (GLA) can play a significant role in combating all inflammatory problems, particularly dermatological diseases. The positive effects are particularly clear in allergic animals.

A little background information

GLA is used in cosmetics products that claim to restore the skin’s elasticity. It is especially good for dry skin or when excessive sebum is produced (seborrhoea).

Its role in the body

Enriching the food with GLA helps its incorporation in the liver, red blood cells and the vessel walls.
Unsaturated fatty acids such as GLA help the cell membranes maintain their fluidity, which is an essential condition for vital exchanges between cells. GLA supplementation intensifies the production of hormones with well-documented anti-inflammatory effects, type 1 prostaglandins. This production is at the expense of the synthesis of type 2 prostaglandins, which have a pro-inflammatory effect.

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Omega 3 fatty acids

Health and prevention

Due to their biological roles, omega 3 fatty acids are used in food for sports dogs, ageing dogs, and animals suffering from chronic inflammatory disorders (osteoarthritis, chronic renal failure, inflammatory diarrhoea, skin diseases).

A little background information

Omega 3 fatty acids form a specific family in the class of polyunsaturated fatty acids. This family is derived from alpha-linolenic acid (ALA), a fatty acid containing 18 carbon atoms and three double chemical bonds. Two other longer but very important fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are derived from ALA.

Its role in the body

The essential functions of omega 3 fatty acids make them interesting in many respects:
- they are anti-inflammatory agents, inhibiting the synthesis of certain chemical inflammation mediators;
- they improve brain oxygenation (especially in old animals) and enhance the performance of dogs active in sports;
- they stimulate the learning capacity of puppies.

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EPA et DHA

also known as: eicosapentaenoic acid and docosahexaenoic acid

Health and prevention

Very long-chain omega 3 fatty acids (EPA and DHA) are especially known for their anti-inflammatory role. Enriching the food with EPA and DHA has many other benefits however:
- they protect the cardiac and kidney functions (blood thinning and anti-hypertensive action)
- they limit the risk of tumours.
There is a high concentration of EPA and DHA in the retina: supplementation during gestation and the first weeks of life increases the animal’s visual acuity.

A little background information

DHA is sometimes known as cervonic acid, because the brain is the organ with the highest concentration. Wild carnivores, especially felines, consume DHA when they eat the brains of their prey.

Its role in the body

Present in maternal milk, EPA and DHA are indispensable to the development of the embryo’s and the foetus’s brain and retinas. The higher the DHA concentration in the maternal milk, the greater the maturity of the young animal’s nervous system.

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Conjugated

fatty acids also known as: CLA

Health and prevention

Conjugated fatty acids derived from linoleic acid – conjugated linoleic acid (CLA) – have been studied as part of the fight against obesity. A particular form of CLA (or isomer) prevents the build up of triglycerides in adipocyte cultures.

A little background information

CLA does not reduce the body weight of human obesity patients, but it does help increase the lean mass (muscles) at the expense of fat (adipose tissue). CLA also has a positive effect on the body composition of dogs fed ad libitum.

Its role in the body

CLA’s anti-adipogenic action is said to be due to an effect of the regulation of glucose and fatty acid metabolism in the adipose cells. The various CLA isomers have been widely studied due to their potential beneficial properties: effects on cancers, atherosclerosis, the immune function and diabetes.

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PROTEINS

Dogs require a lot of proteins. Some physiological conditions are more demanding than others: generation or regeneration phenomena like growth, gestation, lactation and physical effort for example.

Proteins are molecules made up of amino acids in a predefined chain that determine their nature and their roles. Amino acids, which are produced by the degradation of dietary proteins in the digestive tract, then serve as a basis of the body’s synthesis of the proteins it needs to build or regenerate its organs and structures, convey certain molecules, send messages from one organ to another (hormones) and combat disease (antibodies), among other things.

Proteins are found in concentrated form in animal products (meat, fish, eggs, dairy products) and some vegetable products (cereal gluten, lentils, peas, soy, yeast). The cereals added to dog food also help provide proteins.

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Amino acids

Health and prevention

Some proteins are so complex and chemically “solid” that they cannot be broken down by digestion so the amino acids cannot be absorbed in the intestine. They accordingly have no dietary or nutritional value for the animal. This is the case with feathers and hair for example.

A little background information

Amino acids are the building blocks of proteins and their derivatives. Proteins contain a total of about 20 amino acids, only 10 dogs of which must be provided in dog food as they are not produced by the body. Other amino acids must also be provided in food, but they make up a relatively smaller proportion of the total protein intake, as their role is less specific.

Its role in the body

Amino acids from dietary proteins are the building blocks of all proteins synthesised by the body to ensure its vital operation and physiological functions.

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Essential amino acids

Arginine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine

Health and prevention

The absence in the diet of any of these essential amino acids stops the synthesis of life-sustaining proteins. The animal then uses its natural proteins to synthesise what it needs, which gradually puts its survival in danger.

A little background information

Essential amino acids cannot be synthesised by the body and must therefore be provided by the food in appropriate quantities.

Its role in the body

Essential amino acids are aptly named, since, without them, the body cannot realise any normal protein synthesis.
The growth of puppies will be slowed down, while essential functions such as nitrogenous waste elimination and haemoglobin synthesis will be disrupted in adult animals.

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Sulphur amino acids

Methionine and Cystine

Health and prevention

Sulphur amino acids are essential to the synthesis of the main hair protein keratin. A sulphur amino acid deficiency results in hair loss, a slow down in growth and a generally dry, brittle appearance of the hair.

A little background information

The synthesis required for the maintenance of the skin and the hair may represent up to 30% of an adult dog’s daily protein requirement.

Its role in the body

Only methionine is considered to be an essential amino acid. If cystine is provided in sufficient quantities however, it helps free up methionine for other functions. The metabolism of sulphur amino acids produces sulphuric acid, which is eliminated through the urine. A carnivore’s natural diet, which is rich in sulphur amino acids therefore tends to produce acidic urine.

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Arginine

Health and prevention

Arginine is an essential amino acid for dogs. Newborn puppies fed with mothers’ milk with an arginine deficiency soon develop cataracts that lead to blindness. Arginine is also a nitric oxide (NO) precursor, which relaxes the smooth muscles of the blood vessels. Arginine supplementation may accordingly have beneficial effects in case of heart or kidney disease.