1.0 Introduction

It is important that dogs receive a balanced diet appropriate to their life stage and, if applicable, workload (Wynn, 2013). There are various manufactured brands of tinned and dried feed, all of which claim to be nutritionally balanced (Pavia, 2015). It is not uncommon to find products aimed at specific life stages (Pavia, 2015). Regardless of choice, it is vital that the dog receives a balance of key nutrients and energy sources necessary for its life stage (Straus, 2006).

2.0 Canine nutrition

Protein Amino Acids

Amino acids are central to a dog’s health and fitness (Aspca, 2014). These are needed for the build-up of proteins. Proteins comprise amino acids, of which twenty-five are known to date (Volhard and Brow, 1995). Around ten or eleven of these (figures differ depending on the information source) are essential and cannot be produced naturally by the dog’s body. The other fourteen or fifteen amino acids can be created through a chemical chaining process, which takes place in the liver (Volhard, 1995).

Scientific studies have shown links between aggression and diet; this was thought to be due to the high ammonia concentrations in the blood (Ness, 2010). Ammonia is a nitrogen, the result of a waste product of protein, normally the urogenital system will work efficiently and it makes sure that any waste is safely excreted from the body (Fascetti, 2000). Animals that are fed a high quality, digestible, protein diet, which the dog finds easy to break down, are less likely to encounter problems (Fascetti, 2000). Amino acid concentrations (tryptophan) may be helpful in managing dogs’ behaviour alongside a behaviour modification programme (Becker, 2012). Diet does have an important part to play in canine behaviour. Katao’s (2012) study looked at dogs with issues of high anxiety; improvements were noted by the owners when the dogs were given dietary tryptophan. However, further observations would be needed in order to accurately record findings, as opposed to relying on owner judgements (Ness, 2010).

 

Dogs should be fed twice a day; when hungry they display the same signs as humans, namely their behaviour is affected, they may become irritable, lack concentration and experience energy dips. Blood glucose levels and serotonin are believed to have a strong influence on mood and behaviour in the dog (PDSA, no date). Some manufacturers do not produce a low protein diet, as there is no scientific evidence to prove high protein levels cause aggression (Kerns, 2016). Protein is an essential nutrient from amino acids; it helps support the body, whose structure and function depend on the amino acids to help aid muscle growth, tissue repair and immunity (Kerns, 2016).

 

It is important that the brain chemical receptors receive serotonin; the receptors are mainly made-up of essential fatty acids EPA and DHA. While serotonin is the messenger, it is necessary for the message to be received (Alban, no date). The brain chemical receptors are built principally from essential fatty acids, including EPA and DHA. Salmon oil is one of the best omega fatty acids for dogs (Straus, 2016). In humans an on-going supply of salmon oil, for 3-4 months, can help manage anxiety and depression (Alban, no date). The benefits of salmon oil are now becoming recognised in the nutritional management of behavioural problems in canines.

Carbohydrates

The metabolic requirements of all animals need to have a supply of glucose. This can be provided naturally through endogenous rate which is a natural process that the animal’s body can process or it can be provided through diet (Carbohydrate) (Fascetti A, 2010). There is evidence to show that dogs do not need to be fed carbohydrates as long as the dietary needs are met with a high enough fat and protein source (Rodier, 2016). If the dog’s diet mainly consists of carbohydrates – for example, cereals, wheat and corn – and vegetables then it is highly likely that the dog will have animal protein deficiency. This may lead to ear infections, some forms of epilepsy and cancer, rage syndrome and diseases of the skin, heart, kidneys, liver and reproductive system (Dogfoodadvisor 2014). According to Boler (2011) the dog’s diet should incorporate a balance of nutrients, carbohydrates and amino acids. The best choice for dogs with behavioural problems is a food with a low glycaemic index so that the dog’s energy does not spike in behaviour; with this diet stable blood sugar levels are promoted rather than glucose peaks (Boler, 2011). This helps to have a positive effect on the dog’s serotonin levels, which may help improve concentration and response to training (Boler, 2011).

 

Fats

According to Straus (2008) fat is necessary to provide the dog with energy, supple skin and good hair. The dog’s body also needs fat to help absorb nutrients. Every cell contains fat which helps pass the fat-soluble vitamins A, D, E and K (Table 1) through the body, as well as maintaining a healthy nervous system and transporting oxygen round the body. Studies have looked at diets deficient in fatty acids, reporting some behavioural changes in rodents; for instance, impaired learning ability, increased aggression and stress-related behaviours. Other studies found no difference in behaviours as a result of changing the diet in mice or rats (Bosch et al., 2007).

 

Table 1: Fat soluble vitamins (Foster and Smith, 2016).

Vitamin	Recommended Minimum Daily Dose for Dogs	Toxic Dose (This dose must be given daily for months to create toxicity.)	Sources	Signs of Deficiencies
A	2272 IU/lb of food consumed on a dry matter basis	113,600 IU/lb of food consumed on a dry matter basis	Liver, fish liver oil, vegetables, dairy products	Night blindness, retarded growth, poor quality skin and hair
D	227 IU/lb of food consumed on a dry matter basis	2272 IU/lb of food consumed on a dry matter basis	Sunshine, dairy products, fish liver oil	Rickets, poor eruption of permanent teeth
E	23 IU/lb of food consumed on a dry matter basis	455 IU/lb of food consumed on a dry matter basis	Cold pressed vegetable oils, meats, nuts, green leafy vegetables	Reproductive failure, brown bowel syndrome
K	Synthesized in the body	none	Kelp, alfalfa, egg yolk	Increased clotting time and hemorrhage

 

Water

Water is the most necessary nutrient, without which the dog would die within a couple days (Merck Manuals, 2013). The dog could live up to three weeks without food as long as they have water. Water is needed to digest food, breaking it down and absorbing the nutrients. It also helps the dog to maintain body temperature and flushes out toxins through the eliminative organs, keeping acid levels constant in the blood

3.0 How diet can influence a dog’s behaviour

Food and behaviour

Volhard & Brow (1995) state there is a strong link between what the dog eats and the behaviour it shows. Just as there are claims that many behavioural disorders in children are traced to colouring agents and preservatives in food, so too are some well-known and highly advertised branded dog foods alleged to have a negative impact on canine behaviour. Behavioural issues can be aggression, timidity, inability to learn, obsessive-compulsive disorder and uncontrolled barking (Bosch, 2007).

Preservatives

There are three main preservatives that a dog food manufacturer can opt to use: ethoxiquin, BHA and BHT (Strauss and Kerns, 2010). However, none of these is particularly good for the dog, especially ethoxiquin that has been linked with the cause of long-term illnesses (promoted kidney carcinogenesis, significantly increased the incidence of stomach tumours, enhanced bladder carcinogenesis, significantly increased the number of colon tumours). Furthermore, both BHA and BHT have been associated with cancer in humans. More preferable are natural preservatives such as tocopherols (vitamin E), citric acid (vitamin C) and rosemary extract (Jing Zhu, Weiran Chen, et al., 2013).

 

4.0 Nutritional requirements of the puppy

Puppies

 

(2010) State the milk from the mum remains important until the puppies’ digestive and immune systems have developed sufficiently to cope with new food sources.   There are various weaning complete feeds available that can be soaked. Wynn (2013) states it is fundamental that puppies receive a nutritionally balanced food which is highly digestible and palatable. It is important not to over-feed the puppy in an attempt to encourage quicker growth. This can result in an obese puppy and put undue stress on the pup’s skeletal system, causing bone abnormalities, especially in the larger breeds as they grow at a faster rate. Bone abnormalities can include hip dysplasia and wobbler syndrome (Richardson, no date). With a good quality diet, supplements are not needed; in fact, care needs to be taken with cod-liver oil, which is rich in vitamins A and D and can lead to skeletal abnormalities (Richardson, no date).

 

5.0 Nutritional requirements of the senior dog

Light Foods

 

foods are generally used for older or overweight dogs; however, they can be dangerous if not supplemented properly as they lack animal protein, are generally low in fat and high in fibre and mainly contain undesirable preservatives (Bosch, 2007). Dogs that reach the final third of their expected life span are classed as geriatric. The aim is to increase the life span of the dog and to help slow or prevent metabolic changes which can be seen in older dogs (Lane 1999). Senior dogs usually have 20% less energy than that of a younger adult dog; this can be because the dog finds it harder to move or due to a reduction in lean body tissue. Wilde (2007) states that more protein needs to be added to the dog’s diet, though this has to be of the right kind, since if the dog puts on too much weight this places strain on both the skeletal system and the heart. Older dogs can have issues with renal failure which a diet with a low phosphorus and reduce protein slightly see table 2 for further issues due to aging, normally protein levels in older dogs should be of biological value and palatable; if the food is not palatable the dog will not eat, thereby not receiving sufficient nutrition (Wilde, 2007).

 

6.0 Nutritional requirements of the adult dog

Life Style

There are various foods available in the supermarkets, varying from high quality ‘premium’ ranges to economy produce, the latter tending to contain cheap ingredients and bulking agents (Willows General Practice Service, no date). If the dog is a normal pet and stays at home all day then it would be better on a higher carbohydrate food as it helps to keep the dog calmer. Alternatively, if the dog goes out daily for long walks then a super-premium food would be better suited for its higher protein level and fat content. There are also foods created for working dogs; these are designed to release energy evenly throughout the day. If it’s a working dog it is necessary to know which types of food are best to use and why one third of the dog’s energy goes into digesting its food. Dry food stays in the digestive tract for fifteen to sixteen hours, canned food for eight to nine hours, and raw food four to five hours (Volhard, 1995). Case (2005) states that data collected from sleigh dogs in a racing team in the Alaskan bush showed that the dogs consumed more than 9000 calories a day. Dogs that take part in high-energy work in cold temperatures use more energy than if they were doing the same job in warm climates. See table 3 for what types are manufactured.

Table 3 Pet food manufactures (Lane, 1999)

7.0 Pet food manufacturers

There are many different foods to choose and each dog is different; just like humans one diet might work for one dog but not another. These diets include dry foods with a moisture content of 10%-14% and the option of complete or a mixer (Lane,1999). Wet food usually comes in cans with 60%-85% moisture, usually set in jelly or gravy. Semi-moist have 25%-40% moisture and have a mixture of cereal and meat content (Lane, 1999).

Labels

Ingredients are typically listed on dog food packaging, with the highest ingredient listed first (U.S. Food and Drug Administration, 2010). An example is shown in table 3 below:

Table 4: Composition of Eden Dog Food
Salmon	22.5%
Herring	21.5% (from Dried Herring)
Fish	7% (from dried fish) (including seasonally available* Cod, Haddock, Hake, Plaice and Pollock *dependent on the “Catch of the Day”)
Salmon	7% (from Dried Salmon)
White Fish	6%
Trout	6%
Salmon Oil	6%
Sweet Potato	6%
Potato	5.5%
Chickpea	5%
Pea Fiber	2.5%
Whole Egg	2.5% (from Dried Egg)
Salmon Stock	1.5%
Lucerne, Minerals & Vitamins, Carrot, Spinach, Apple, Rosehips, Camomile Powder, Burdock Root Powder, Aniseed & Fenugreek, Seaweed, Cranberry, Fructooligosaccharides (461 mg/kg), Glucosamine (341 mg/kg), MSM (341 mg/kg), Chondroitin Sulphate (240 mg/kg), Thyme, Marjoram, Oregano, Parsley, Sage.

 

 

 

 

8.0 Conclusion

 

Similar to humans, canines need essential amino acids, fatty acids, water, energy, vitamins and minerals (Lane, 1999). It is essential the diet caters for the breed, age and workload of the individual dog. The diet must contain the right balance of carbohydrates, fat and protein to enable the animal to have sufficient energy and nutrients (Lane, 1999). Many dog owners choose commercially-available food mixes and it is important that they select the most appropriate option for the animal’s life stage. If the dog is naturally excitable and a high protein food is added then there will be a lot more energy to burn.