The Food

Food and the Essentials of Nutrition

Nutrition is crucial for a dog’s survival and well-being. It provides the energy and resources necessary for their overall health and activity. Nutrients are dietary components that play specific roles in the body. They can be classified as essential or non-essential. Essential nutrients must be obtained through the diet, while non-essential nutrients can be produced by the body if suitable precursor substances are present. A dog’s diet must include six types of nutrients: water, fat, protein, carbohydrate, vitamins, and minerals. Food also provides energy through dietary fat, protein, and carbohydrate - the macronutrients that provide energy.

The Components of Food

Food is composed of dry matter (DM) and water. High-moisture foods, such as raw meat or canned dog food, have lower levels of DM per volume than dry food. The DM contains the nutrients. The DM can be further divided into organic and inorganic fractions. These terms refer to the chemical composition of the compounds within these groups. Organic compounds contain the element carbon, while inorganic compounds do not.

The components of food.

The organic fraction of food DM includes fat, carbohydrate, protein, vitamins, and minor nutrients such as organic acids. The inorganic fraction contains minerals such as calcium and iron. This fraction is often listed on pet food labels as “ash,” which can cause confusion for caregivers. Ash refers to the minerals in the food and does not mean that ash has been added to the dog’s food.

Fat, protein, and carbohydrate provide energy in the diet and are considered macronutrients because they are needed in larger quantities than micronutrients. Micronutrients include vitamins and minerals, which are essential for health but only needed in small amounts. Laboratory tests are used to assess the nutrients and amounts supplied by food and individual ingredients. If you are preparing your dog’s food at home, you may use reference tables of this information to formulate the overall diet.

The Nutrients

Dogs require nutrients, and different food ingredients supply these nutrients in varying forms and amounts. Understanding the nutrients provided by ingredients is essential in formulating a dog’s diet. If you are using commercial dog food, knowing about the ingredients and their nutritional value can aid in decision-making. Assessing a diet based on its nutrient provision is more effective than simply looking at its ingredients.

Food ingredients provide the nutrients dogs need. Nutrients can be tailored to individual dogs and circumstances by changing the types or amounts of ingredients in their diet. If you are feeding commercial dog food, the ingredients may affect your purchasing choices. You may wish to avoid certain ingredients for health, welfare, sustainability, or price reasons. If you are preparing your dog’s food at home, you’ll need to understand how different ingredients can be combined to provide a nutritionally balanced and suitable diet. Not all nutrients are equal. For example, different sources of protein vary in digestibility. Fat may be sourced from plants or animals, affecting the overall composition. Carbohydrates can be soluble and rapidly digested or insoluble and indigestible.

Nutrients and Energy: Food as Fuel

Food not only supplies essential nutrients to dogs but also fuels them. It provides the energy they need to perform all their activities, and a constant source of energy is necessary for survival. While energy itself is not a nutrient, food must supply adequate levels of energy-providing nutrients to support health and well-being. A dog’s diet must meet their energy requirements first and foremost, with 50-80% of their DM intake used for energy. Energy-providing nutrients will meet energy needs before being used for any other purpose in the body. If a diet does not supply sufficient energy, a dog will lose weight and body condition and may even break down their own muscle mass to obtain energy. Prolonged energy deficits can result in ill-health and can eventually be fatal. Conversely, excess dietary energy can cause a dog to gain weight and potentially develop overweight or obesity.

How Does Food Supply Energy?

The nutrients that provide energy in a dog’s diet function as energy stores and fuel sources. They store energy in their chemical structure, and when this structure is broken down during digestion and absorption, energy is released. Dogs use this energy to support the maintenance of their body and their activity output.

How Much Energy Does My Dog Need from their Food?

Dogs require different amounts of food energy based on their individual circumstances, such as age and activity level. Young, active dogs need more energy to support growth and exercise than older, less active dogs. Many caregivers “feed by eye” and adjust the amount of food they give their dogs based on their appearance and performance. However, it is better to have an idea of how much energy a dog is likely to need and use calculations to make evidence-based dietary choices. This may involve changing the amounts of individual nutrients in the diet to make it more or less energy-dense.

Energy Requirements of Different Dogs

It is possible to calculate a dog’s estimated energy requirements based on their body weight and activity level. This provides an idea of the amount of energy a diet must supply each day to support the maintenance of body tissues and activity output.

Dog coats are useful to keep them clean and dry, but also reduce their daily energy requirements.

For many companion dogs, their energy requirement is that of maintenance - enough energy must be supplied to support the day-to-day maintenance of the body. Most companion dogs have limited energy expenditure, may be spayed or neutered, live in warm homes, and may even wear dog clothing. However, this same population of dogs is often given calorific treats and may have other lifestyle factors that predispose them to weight gain.

On the other hand, some dogs have increased energy requirements that must be reflected in their diet. A dog’s age affects their energy requirements throughout their life. Young, growing dogs have increased energy needs to support growth and the increased activity common in younger animals. Puppies also have limited thermoregulation capacity and need energy to generate body heat. As dogs mature, growth slows and body maintenance becomes a more consistent process of turnover, repair, and regeneration that requires less energy than active growth. Voluntary activity often decreases with maturity as well. Spaying or neutering can also reduce a dog’s energy requirements.

Illness, recovery, and healing after injury or surgery can increase a dog’s energy requirements. If illness has caused digestive upset and disturbance, a recovery diet may be needed for a prolonged period. A diet with increased energy provision can support the recovery process and allow for small, energy-rich, and nutritious meals to be provided.

As dogs age, wear and tear on the body and the aging process can affect activity levels, reducing energy needs even further. Musculoskeletal pain, such as from osteoarthritis, can limit movement and increase the risk of weight gain without careful management of dietary energy intake. Age-related changes to dentition and the digestive system can also impair food intake and energy acquisition from the diet.

Pregnant dogs require an increased amount of dietary energy during the last weeks of pregnancy. They may also need more frequent meals to compensate for the reduced capacity of the digestive system to handle large volumes of food if carrying a large litter. Lactation is extremely energy-demanding and requires additional dietary energy. For dogs nursing large litters, milk production can place an incredible demand on the body when puppies are between three and five weeks old. It is essential that the diet provides enough energy to support both the mother and her puppies.

Pregnancy and lactation require additional dietary energy.

Highly active and working dogs require an increased supply of energy through their diet. Handlers of hard-working or highly active dogs often report that their dogs struggle to maintain body weight during a working or competitive season. The demands of hard work, high levels of daily activity, travel, competition stress, and other factors can make it difficult for these dogs to eat and digest enough calories each day to maintain body condition. Sled dogs competing in long-distance races can lose a substantial percentage of their body weight during the race and may have a daily calorie requirement exceeding 10,000 kilocalories (kcal) per day. For comparison, the recommended daily calorie intake for an adult human female is approximately 2,000kcal per day.

Assessing an individual dog’s energy requirements based on their age, breed/type, lifestyle, activity level, health, and other factors is essential. If you would like to take a more scientific approach to calculating their needs, Chapter Energy explores how to do so.

Ingredients and Sustainability

When considering our dog’s food, we have a responsibility to consider its nutritional value, the energy and nutrients it provides, and its environmental impact. Balancing these factors against our own and our dog’s needs requires careful consideration. Awareness of the origin of ingredients is increasingly important from a sustainability perspective. Environmental and geopolitical challenges can make some ingredients difficult to source or expensive. Ingredients that must be transported across the world have a significant carbon footprint. Animal-derived ingredients can be particularly problematic due to their environmental impact during production and their use in dog food may compete with the human food chain. This is a growing concern with the rise in the use of “human-grade” material in dog food. As a result, alternative ingredients, such as insect proteins, are being used. These ingredients are nutritionally valuable and acceptable to dogs, but some caregivers remain concerned that diets including these ingredients are not appropriate for dogs. The debate about “species-appropriate” feeding continues. Sustainability, availability, and affordability will all impact how and what we feed our dogs in the future.

Digestibility of Food

The digestibility of food is an important factor in determining whether and how much of its nutrients are available to dogs. No food is 100% digestible, and there is always some indigestible material that passes through the digestive system and is eliminated as waste. Much of this indigestible material is fiber, which is still beneficial for the health of the digestive system by providing material for the intestinal microbiome to feed on, bulking stools, and removing old cells from the digestive tract.

Digestibility is affected by several factors, including the level of processing, ingredients, fiber content, and the health and activity level of the dog. Dietary fat is approximately 90% digestible, while carbohydrate and protein are approximately 85% and 80% digestible, respectively. However, not all forms of nutrients are the same. For example, shoe leather is high in protein but not very digestible. Raw meat is considered highly digestible compared to heavily processed diets. However, comparisons of different food types suggest that lightly cooked/steamed chicken breast is more digestible than raw chicken, which in turn is more digestible than dry chicken-based dog food.

In general, high-quality, well-prepared and formulated diets tend to be more digestible than low-quality diets. This means that less of a highly digestible diet needs to be fed to meet nutritional needs. However, appetite and gut fill must also be considered - we don’t want our dogs to feel hungry all the time. A balance often needs to be struck between digestibility and the volume of food fed. Sometimes highly digestible diets fail to satisfy our dogs because of the small nutrient-dense volume fed. In such cases, alternatives may be needed.

What about ‘Fillers’ in Dog Food?

Fillers are often described as low-cost ingredients with no nutritional value in dog food. However, all ingredients have either a nutritional or processing role, so the term “filler” is somewhat inaccurate. Some ingredients, such as indigestible fiber, may be used to provide bulk to a diet. This can be useful in weight-management diets and can help bulk stools and support anal gland emptying. Water and air can also be considered fillers - both can make a meal appear larger than it would otherwise be (think of the difference between popcorn kernels and popped corn). Both are used to aid feelings of fullness in dogs. While water is an important nutrient, air can justifiably be considered a true filler.

The Importance of Water – the First Limiting Nutrient

Water is essential for supporting life and is one of the most basic requirements for any living organism. It is often taken for granted, but its importance cannot be overstated. Water is considered the first limiting nutrient because deficiency can have rapid and significant impacts. Even mild dehydration can affect a dog’s ability to exercise, learn, and regulate their body temperature. About 65% of a dog’s body weight is water. A loss of 10% body water can result in severe health consequences, and a loss of up to 15% can be fatal.

Water supports temperature regulation, waste removal, and digestive function. It is called the universal solvent because many substances can dissolve in it and metabolic reactions depend on it. The minimum daily water requirement for dogs varies based on individual circumstances. Dogs continually lose water through evaporation from the respiratory system, urination, and in their feces. Dogs can be negatively affected by a lack of water within hours, while a lack of food takes much longer to have a significant impact. For this reason, a constant supply of drinking water is recommended.

Sources of Water

There are three sources of water for dogs: drinking water, water in food, and metabolic water produced as a by-product of metabolic reactions in the body. Drinking is the most significant source of water for most dogs. Food with high moisture content can also provide a useful source of water, and dogs fed wet food often drink less than those on dry diets.

The three sources of water: 1, Drinking. 2, Food. 3, Metabolic

Drinking Water

Dogs may drink from a variety of water sources, including those that are less than ideal and may be contaminated, such as puddles. While drinking from unclean sources should be discouraged and not relied upon as a source of drinking water, most healthy dogs show no ill effects. However, there is a risk of ingesting disease-causing organisms such as Leptospira spp. (a bacteria typically spread by rats) and Giardia spp. (a parasite originating from livestock and infected dogs) that can cause illness. Providing a consistent and clean supply of drinking water in a bowl large enough for your dog to safely fit their muzzle and lap from is a simple but essential aspect of canine care. While bowls are available in various materials, a stainless-steel bowl is easy to clean and sterilize and is less likely to harbor potentially pathogenic organisms than other materials.

Dogs will often be less choosy about where they drink than we might like.

Water in Food

Raw or moist diets can contain up to 80% moisture, but drinking water is still necessary. Water intake is much higher for dogs fed dry food. Soaking dry food can encourage water intake and support digestion and palatability. Dry foods are often coated with fats and oils that are released when water is added, enhancing the smell, taste, and acceptance for some dogs. However, boiling water should not be added to dry food as it can destroy heat-sensitive nutrients. Additionally, soaked food should not be left uneaten at room temperature for extended periods due to the risk of bacterial growth.

Metabolic Water

Metabolic water production accounts for only a small proportion of a dog’s daily water requirement (between 5 and 10%) and cannot be relied upon exclusively as a source of water.

Practical Water Provision for Your Dog

It is good practice to know your dog’s typical daily water intake. While this may increase if temperatures are high or your dog has been active, unusual and unexplained increases in water consumption may indicate other problems. Seek veterinary advice if there are sudden changes in your dog’s drinking habits. This is especially important for unspayed female dogs, as increased drinking can be a sign of pyometra (infection of the uterus) and requires prompt veterinary attention. For older dogs, changes in drinking habits may suggest age-related disease, so it is important to speak to your vet.

Many factors affect how much water a dog will drink each day, including diet, temperature, exercise, age, health, and individuality. Increased ambient temperatures, extreme exercise, and high-fat, high-protein diets all increase water intake to support metabolism, cooling, and waste removal. Pregnant, whelping, and lactating female dogs also increase their water intake, especially if they have a large litter and during weeks three to five after whelping when milk production and consumption are at their highest.

A useful way to check your dog’s hydration status is to assess their urine output, frequency of urination, and urine color. If urine is very dark and passed infrequently or in small amounts, this may indicate dehydration. Healthy urine should be lightly straw-colored and not excessively smelly. If there are significant changes in urine output, appearance or frequency, seek veterinary advice.

Keeping water bowls clean and regularly refilled with fresh, clean water is one of the simplest things we can do to support our dogs’ overall health and well-being in addition to feeding them well.

A fresh, clean supply of drinking water should be always available. Water bowls should be cleaned and refilled regularly.

The Importance of Dry Matter (DM) for Nutrition

To accurately evaluate the nutritional value of dog food, it is important to determine its dry matter (DM) fraction and moisture content. Wet dog food has a higher moisture content than dry dog food. The DM basis of a food is crucial in calculating the amount required to meet a dog’s nutritional needs and in comparing the nutrition provided by different foods. Nutrient values on dog food labels are listed as percentages under the heading ‘analytical constituents’ and are based on total weight, including moisture. However, to effectively compare nutrient values across different types of food, they must be evaluated on a DM basis (DMB).

How Can I Calculate Nutrient Content on a DMB?

To compare the nutrition provided by different foods, it is necessary to calculate the nutrient content of each food on a dry matter basis (DMB). This requires knowledge of the nutrient values declared on the label and the moisture content of the food. If the moisture content is not specified, as is often the case with dry food, a typical moisture content of 8% can be assumed. The calculated DMB value will generally be higher than the labeled nutrient value due to the removal of water from the calculation. For high-moisture foods, calculated DMB values will be higher than for dry diets. The following steps can be used to calculate the amount of a nutrient on a DMB:

1. Calculate the dry matter content of the food by subtracting the moisture content from 100, e.g. a dry food with a moisture content of 8%:

   100 — 8 = dry matter of 92%

2. Divide the percentage value of the nutrient of interest by the dry matter value, e.g. a dry food with 24% protein and dry matter of 92%:

   24 ÷ 92 = 0.26

3. Multiply the value from step 2 by 100 to give the DMB percentage, e.g. calculated 0.26 protein in step 2 (above):

   0.26 × 100 = 26% protein DMB

Example of a DMB calculation for the protein and fat content of a wet dog-food.

Calculating nutrient levels on a dry matter basis (DMB) allows for the comparison of the nutritional value of different types of dog food. For instance, at first glance, it may appear that feeding a raw diet would result in a lower protein intake for your dog due to the lower percentage of protein listed on the packaging compared to dry food. However, when calculated on a DMB, the protein content may actually be higher than initially thought. This is important when considering the role of food in your dog’s nutrition.

What Do these Percentage Values for Nutrients Mean?

The analytical values on labels and those calculated on a dry matter basis (DMB) provide an indication of the amount of a given nutrient supplied in a specific quantity of food. For example, if the protein content is calculated to be 32% DMB, this means that 32% of the food on a DMB is protein. In other words, if you feed your dog 100g of food on a dry matter basis, 32g of that will be protein. However, it is important to note that not all of the protein will be available to your dog as not all of it will be digestible or bioavailable. These values can be used to determine if your dog’s food is providing the right amount of nutrients and to make dietary adjustments to meet your dog’s needs.

Summary

• Dogs require nutrients, which are supplied by food in varying forms and quantities.
• Food is composed of a dry matter (DM) fraction and water, and different types of food can be compared on a dry matter basis (DMB).
• There are six classes of nutrients: proteins, fats, carbohydrates, vitamins, minerals, and water.
• Proteins, fats, and carbohydrates are macronutrients that provide energy in addition to performing other biological functions.
• Vitamins and minerals are micronutrients that are essential for normal bodily function.
• A dog’s energy needs must be met by their diet before anything else, and water is also crucial for survival.