The Potential Harms of Poor Dog Diets
‘Could their food be aging my dog?’ It’s a question most of us have probably never considered. We are all more likely to ask, ‘What’s the best food for my dog?’ Understanding what the best food to slow aging in our dogs is, requires us to understand what makes one food better than another.
In this article we look at what our dogs require from their nutrition to support their best health and wellbeing and those aspects of their nutrition that can be negative, and at times silently harmful, in the long-term.
The following are aspects of dog food that can have a negative impact on dog health.
For more detailed information navigate to the relevant section in the article below.
- High protein levels – consumption of high protein food over the long-term increases in metabolites associated with kidney dysfunction, inflammation, and proteolysis. May also lead to increased fat storage and all the health problems associated with being overweight
- Insufficient fibre levels – can lead to digestive issues, lack of satiety, anal gland problems, as well as reduced insulin management
- Carbohydrate types – wheat, corn and soy are amongst the top 10 allergens for dogs. Use of simple vs complex carbohydrates can lead to detrimental insulin responses
- Essential Fatty Acids – Omega-3 (DHA, EPA and DPA) are anti-inflammatory and vitally important for dogs immune and cognitive health. An Omega-6 : Omega-3 imbalance can be pro-inflammatory with negative impacts on dog health
- Mineral forms – inorganic minerals, particularly Zinc, are not absorbed and utilised by dogs as well as chelated minerals
- Production method – high temperature cooking can have many consequences including reduction of nutrients and denaturing of proteins, and the consumption of AGE’s (advanced glycation end products) is potentially harmful for dogs
Elements of Dog Food That Provide Natural Health Support
The following are aspects of dog foods that that elevate dog food beyond simple nutrition, providing dogs with complete and balanced nutrition that is also ant-inflammatory and antioxidative, both of which support your dog against the most common health issues they are likely to suffer from through their lives.
These will also help to support your dog against ageing, and declining health, caused by inflammation known as inflammaging.
- Medium protein levels – 21-29%
- Fibre levels between 4-6%
- Use of complex carbohydrates with low Glycaemic index and load
- Inclusion of Omega-3 with DHA and EPA and an Omega-6: Omega-3 ratio between 1:1 to 4:1
- Inclusion of effective probiotics
- Inclusion of prebiotic fibres to feed the dog microbiota
- Inclusion of clinically tested herbs, botanicals and adaptogens that provide holistic health support
- Food that is cooked at low temperatures to preserve nutrient integrity
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Contents:
- A Review of the Causes of Human Morbidity and Mortality and Translational Impacts for Dogs
- Chronic inflammation in the Aetiology of Disease Across the Life Span
- Causes of Chronic Inflammation and Senescence
- Strategies for the Prevention and Reduction of Inflammation
- Physical Activity and Exercise
- The Physical and Mental Benefits of Daily Activity
- Treatment and Prevention of Dysbiosis in Dogs
- How Nutrition Contributes to Inflammation and Ageing
A Review of the Causes of Human Morbidity and Mortality and Translational Impacts for Dogs
In answering this divisive, and controversial, question it is important to understand that Science is beginning to understand, notwithstanding the ethics and morals, that our dogs are excellent models for better understanding our own health. That our dogs provide a model for clinical trials, and health research, more closely aligned with, and resembling, our own than the porcine (pig), ovine (sheep) and murine (mouse and rat) models most often used in trials.
Current evidence suggests that dogs share important anatomical, physiological, histological, and molecular components of many of the chronic diseases humans suffer from – cancer, diabetes, obesity, osteoarthritis, cardiovascular, dementias, periodontal, epilepsy, hyperthyroidism and colitis and IBD (inflamed bowel disease), et al (1, 2. 3, 4)
The physiological similarities between humans and dogs mean that they are useful in various types of research. Their genome has been sequenced and because of our genetic similarities, they are often used in genetic studies.
They are primarily used in regulatory research, also known as toxicology or safety testing. This type of research is required by law to test the safety and effectiveness of potential new medicines and medical devices before they are given to human volunteers during clinical trials.
Dogs are also used to test the safety and efficacy of veterinary medicines, and in nutrition studies to ensure that pet dogs eat healthily, particularly when they are prescribed specialist diets by their vets.
Fewer dogs are used in translational research to help us learn about human and animal diseases so that we can develop treatments. Examples of specific translational diseases include Duchenne muscular dystrophy (DMD) and diabetes.
An early use of dogs in research was in the search for a treatment for diabetes, which resulted in the discovery of insulin (5). This discovery has resulted in millions of diabetes sufferers leading long, more comfortable, lives
Research suggests that the companion dogs may be the ideal translational model to study the many complex facets of human morbidity and mortality. (6, 7, 8, 9) In turn the reverse is true, understanding the impacts of various factors on human health and mortality can be translated to our dogs.
As significantly more research is conducted into the causes of human morbidity and mortality, we propose that identifying the greatest risks to human health, also identifies the greatest risk to dog health and longevity.
Chronic inflammation in the Aetiology of Disease Across the Life Span
Amongst the most important medical discoveries of the past two decades has been that the immune system and inflammatory processes are involved in not just a few select disorders, but a wide variety of mental and physical health problems that dominate present-day human morbidity and mortality. (10, 11, 12, 13)
Chronic inflammatory diseases have been recognised as the most significant cause of death today, with more than 50% of all deaths being attributable to inflammation-related diseases such as ischemic heart disease, stroke, cancer, diabetes mellitus, chronic kidney disease, non-alcoholic fatty liver disease (NAFLD) and autoimmune and neurodegenerative conditions. (14)
While a normal inflammatory response is characterised by a temporary, and restricted, upregulation of inflammatory activity when a threat is present, that resolves once the threat has passed (15 16 17 18),
However, chronic, persistent inflammation is entirely different. The presence of certain social, psychological, environmental and biological factors has been linked to the prevention of resolution of acute inflammation and, in turn, the promotion of a state of low-grade, non-infective systemic chronic inflammation (SCI) that is characterised by the activation of immune components that are often distinct from those engaged during an acute immune response. (16 19)
In plain English the differences can be described in this way: Acute inflammation: The response to sudden body damage, such as cutting your finger. To heal the cut, your body sends inflammatory cells to the injury. These cells start the healing process. Chronic inflammation: Your body continues sending inflammatory cells even when there is no outside danger.
While acute inflammation and chronic inflammation share many common mechanisms of reaction, the main difference lies in the resolution of the response in the case of acute inflammation, or lack of resolution in the case of chronic inflammation.
With acute inflammation, the body produces multiple molecules that contribute to the resolution of the inflammation (20, 21). In contrast, chronic inflammation is typically triggered in the absence of an acute infectious insult. Chronic inflammation typically increases with age (22)
Chronic inflammation (SCI) is low-grade and persistent and ultimately causes collateral damage to tissues and organs over time, by inducing oxidative stress (23, 24, 25,26)
The clinical consequences of SCI-driven damage can be severe and include an increased risk of the metabolic syndrome, which includes the unhealthy trio – hypertension, hyperglycaemia and dyslipidaemia (27 28); type 2 diabetes (27); non-alcoholic fatty liver disease (NAFLD) (27 29); hypertension (30); cardiovascular disease (CVD) (31 32); chronic kidney disease (32); various types of cancer (33); depression (34); neurodegenerative and autoimmune diseases (35 36 37); osteoporosis (38 39) and sarcopenia. (32)
Chronic inflammation in older individuals is thought to be caused in part by a complex process called cellular senescence, or inflammaging.
Senescent cells promote a multitude of chronic health conditions and diseases, including insulin resistance, CVD, pulmonary arterial hypertension, chronic obstructive pulmonary disorder, emphysema, Alzheimer’s and Parkinson’s diseases, macular degeneration, osteoarthritis and cancer. (40 41)
Causes of Chronic Inflammation and Senescence
How senescent cells generate is not fully understood, but existing research points to a combination of both endogenous (internal) and non-endogenous (external) social, environmental and lifestyle risk factors. Among the known endogenous causes are DNA damage, dysfunctional telomeres, epigenomic disruption, mitogenic signals and oxidative stress (42). The non-endogenous contributors are thought to include chronic infections (43), lifestyle-induced obesity (44), microbiome dysbiosis (45), diet (46), social and cultural changes (47 48) and environmental and industrial toxins. (49)
Chronic Infections:
Although chronic infections have been shown to increase the risks of a pro-inflammatory regime, and studies have reported associations between chronic infections and autoimmune diseases, certain cancers, neurodegenerative diseases and CVD, these infections have been shown in studies to react with environmental and genetic factors to influence health outcomes. (50 51 52)
Studies have shown that populations of hunter-gatherers and other existing non-industrialised societies such as the Shuar hunter-gatherers of the Ecuadorian Amazon (53 54), Tsimané forager-horticulturalists of Bolivia (55), Hadza hunter-gatherers from Tanzania (56), subsistence agriculturalists from rural Ghana (57) and traditional horticulturalists of Kitava (Papua New Guinea) (58)—all of whom are minimally exposed to industrialised environments but highly exposed to a variety of microbes—exhibit very low rates of inflammation-related chronic disease and substantial fluctuations in inflammatory markers that do not increase with age. (59 56 55 53 58)
Lifestyle, Social and Physical Environment
The relative absence of chronic inflammation related health problems in the populations noted above has not been attributed to genetics or to having a shorter life expectancy, but rather to lifestyle factors and the social and physical environments the people live in (60) . Their lifestyles, for example, are characterised by higher levels of physical activity (61 62 63), diets composed mainly of fresh or minimally processed food sources (64 65 66), and less exposure to environmental pollutants. (67) In addition, the social stressors they experience are different from those typically present in industrialised environments. (68)
These social and environmental characteristics are believed to have predominated during most of hominin evolutionary history until industrialisation (69 70 71).
Whilst industrialisation provided numerous benefits for man – social stability, improvements in medical technology and health management which improved longevity overall, more recently radical changes in lifestyles and diets are considered to be the most significant contributor to chronic inflammation, senescence and inflammaging. (71, 72 ,73, 74, 75)
Physical Activity
Industrialisation has led to a big drop in how active people are. A study found that 31% of people around the world don’t get enough exercise, and this is more common in richer countries. In the U.S., it’s even higher at about 50% of adults not being active enough. (76, 77)
Our muscles are not just for movement; they also release special proteins, called myokines, when they contract. These myokines can lower inflammation in our bodies (78). Not exercising enough is linked to higher levels of inflammation and other unhealthy changes in our bodies (79, 80, 81, 82). This can lead to problems like insulin resistance, high cholesterol, high blood pressure, and muscle loss (83). These issues increase the risk of heart disease, diabetes, liver disease, osteoporosis, certain cancers, depression, dementia, and Alzheimer’s disease, especially in people who don’t exercise regularly. (84, 85)
There’s strong evidence showing that not exercising enough can lead to more age-related diseases and even early death. A big study with over 1.6 million people showed that doing at least 150 minutes of moderate exercise a week can lower the risk of heart disease death by 23%, heart disease by 17%, and diabetes by 26% (86). Another study with 1.44 million people found that those who don’t exercise much have a much higher risk of getting several types of cancer (87). Also, older adults who meet exercise recommendations have a 40% lower risk of Alzheimer’s disease (88).
Not exercising can also increase the risk of diseases not spread by infections, partly because it’s linked to obesity (89). Extra fat, especially around the waist, causes inflammation (90, 91, 92). This fat is an active organ that can get bigger and cause inflammation by releasing harmful substances. This leads to more immune cells in the fat and more inflammation, which can become a long-term problem (93, 94, 95, 96). This process also causes issues like insulin resistance and can lead to fats building up in organs like the pancreas and liver, causing more health problems (97). Being overweight can speed up aging and increase the risk of heart and metabolic diseases, brain diseases, autoimmune diseases, and some cancers (98, 99, 100, 101, 102, 103). These problems start in childhood and can increase the risk of diseases related to aging later in life (104, 105).
Microbiome Dysbiosis
Obesity can lead to systemic chronic inflammation (SCI) partly because it changes the gut microbiome, the community of microorganisms living in our intestines (106). Studies in moderately obese Danes without diabetes (107) and severely obese French women (108) showed that changes in gut bacteria are linked to more body fat, inflammation, and insulin resistance. In older adults, these changes in gut bacteria affect several inflammation pathways (109).
Obesity is also connected to increased gut leakiness and endotoxemia, where harmful bacterial products enter the bloodstream (110, 111). This can trigger inflammation and lead to conditions like insulin resistance (112). High levels of zonulin, a protein that makes the gut leakier, are found in obese children and adults, people with diabetes, liver disease, heart disease, polycystic ovary syndrome, autoimmune diseases, and cancer (113, 114). High zonulin levels are also linked to inflammation and frailty (115).
Several factors may cause gut imbalance and leakiness, including overuse of antibiotics, anti-inflammatory drugs, and acid reducers (116, 117), excessive cleanliness, less contact with animals and nature (118, 119), and diet (120).
Diet
The typical modern diet, low in fruits, vegetables, and fibre-rich foods (121, 122, 123, 124), and high in refined grains (125), alcohol (126), and ultra-processed foods (127), can change gut bacteria and increase gut leakiness (128, 129, 130). This leads to low-grade endotoxemia and SCI (131, 132, 133). Processed foods, especially those cooked at high temperatures, can increase appetite and lead to overeating and inflammation (134). High-glycaemic foods like sugars and refined grains increase oxidative stress and inflammation (135).
Trans fats (136) and dietary salt also affect inflammation. Salt shifts immune cells towards a more inflammatory state and alters gut bacteria (137). A study found that a 10% increase in ultra-processed food consumption raised the risk of death by 14% (138).
Nutritional deficiencies, like in zinc (139) and magnesium (140), and low omega-3 levels (141) also promote inflammation. Omega-3 fatty acids, found in fish and salmon oil, krill and seaweed, help resolve inflammation (142, 143). However, low fish intake and high consumption of certain vegetable oils can lead to low omega-3 levels (144, 145). Omega-3 supplements can reduce inflammation (146, 147, 148).
Poor diet is a major death risk factor, with high trans fats, low omega-3s, and high salt being the top dietary risks in the U.S. in 2005. In 2017 (149), poor diet was the leading death risk factor globally, with excess sodium intake causing most diet-related deaths (150).
Eating highly processed foods, especially when combined with low physical activity, can change cell metabolism and lead to “inflammaging,” a state of chronic inflammation seen in older age (151, 152, 153).
Social and Cultural Changes
Changes in social interactions, sleep quality (154, 155), and increased psychological stress in the workplace can promote SCI and insulin resistance, increasing the risk for obesity, diabetes, heart disease, and overall mortality (156, 157, 158, 159, 160, 161). High job demand and low control can make the body less responsive to inflammation-regulating hormones, leading to poor health (162, 163).
Increased exposure to artificial blue light, especially at night, disrupts our body’s natural rhythms, promoting inflammation and increasing the risk for various diseases (164, 165, 166, 167). Night-shift work, for example, raises the risk for metabolic syndrome and various cancers (168).
Environmental and Industrial Toxicants
Urbanisation has led to more exposure to pollutants and chemicals that promote SCI (169, 170). Thousands of new chemicals are introduced yearly into everyday products (171). High-throughput screening, like the Tox21 Program, tests how these chemicals affect inflammation and disease risk (173, 174). Chemicals like phthalates, flame retardants, and others alter inflammation pathways and are linked to cancers, metabolic syndrome, heart disease, and other illnesses (175, 176). Tobacco smoking, another source of harmful chemicals, is linked to various inflammation-related diseases (177).
While the review of the science above is linked to inflammation, its causes and impact on human health, the great majority of this is equally applicable to our dogs. And if they did drink alcohol, the same impacts would apply to their health!
Unfortunately, our dogs are suffering from the same chronic diseases we are – cancer, diabetes, obesity, osteoarthritis, cardiovascular, dementia, IBD, periodontal and eye issues like cataracts.
While ageing is unavoidable, early ageing and decline, or inflammaging, can be slowed by avoiding, or minimising, triggers of chronic inflammation.
Strategies for the Prevention and Reduction of Inflammation
Fortunately there are a number of actions we can take to reduce, and hopefully prevent, inflammation in our dogs. This in turn will provide them with all they need to avoid the often dire consequences of inflammation.
Physical Activity and Exercise
As important as exercise is to us it is equally, if not, more important for our dogs.
Not only do they benefit from the aerobic activity that walking and playing provides but also from the stimulation they get – social interaction with other dogs and their humans, mental stimulation from the surroundings and the wealth of smells and sounds they encounter on their walks.
it’s crucial to understand that dogs, like humans, require regular exercise to maintain their health and happiness. However, the amount and type of exercise needed can vary greatly depending on several factors. We’ll explore the different exercise needs of dogs, as well as the physical and mental benefits that regular activity brings to our four-legged friends.
Different Dogs Need Different Levels of Daily Physical Activity
Breed-Specific Exercise Requirements
The exercise needs of dogs can vary significantly based on their breed. For example:
- Active Breeds: Breeds like Border Collies, Australian Shepherds, and Labrador Retrievers are known for their high energy levels. They typically require more than two hours of vigorous exercise daily.
- Giant Breeds: Larger breeds such as Great Danes and Mastiffs may need less intense exercise, given their size. Gentle walks and short play sessions are often sufficient.
- Small Breeds: Small breeds like Chihuahuas and Pomeranians need exercise to stay fit, but due to their size, they may tire more quickly. Shorter, more frequent walks are ideal.
- Brachycephalic Breeds: Dogs with short noses, such as Pugs and Bulldogs, often have breathing difficulties, so they require less strenuous activity.
It is estimated that only 60% of dog owners walk their dog (178). The exercise levels of dogs has been shown to be inversely associated with dog obesity, an increasing animal health, and welfare, issue (179, 180, 181).
With over 50% of dogs now considered to be overweight or obese (182, 183), providing our dogs with greater levels of daily physical activity is one way in which we can improve not only our dogs longevity, but also their mental wellbeing.
Age and Health Considerations
Puppies are generally more energetic and may need several short play sessions daily, along with opportunities for socialisation. Senior dogs, on the other hand, might require gentler, less frequent exercise. Always consider any health issues your dog may have, such as arthritis or heart problems, and adjust their exercise routine accordingly.
The Physical and Mental Benefits for Dogs of Daily Activity
Physical Health
Regular exercise is vital for maintaining a dog’s physical health. It helps:
- Keep the heart and lungs healthy.
- Maintain muscle tone and joint flexibility.
- Control body weight and prevent obesity, which can lead to other health issues.
- Improve digestion and reduce constipation.
Mental Stimulation and Behaviour
Exercise isn’t just about physical health; it’s also crucial for a dog’s mental well-being. Adequate physical activity can:
- Reduce anxiety and depression.
- Prevent boredom and associated destructive behaviours, such as chewing, digging, or excessive barking.
- Improve sleep quality.
- Enhance overall mood and happiness.
Socialisation and Training
Walks and play sessions are excellent opportunities for dogs to socialise with other dogs and people, which is crucial for their behavioural development. It also provides a great opportunity to reinforce training commands and improve leash manners.
Bonding Time
Exercise time is also bonding time. Engaging in activities like walking, playing fetch, or agility training strengthens the bond between you and your dog. It’s a chance to understand each other better and build trust and companionship.
In conclusion, dogs need regular exercise to remain physically and mentally healthy. The amount and type of exercise will depend on their breed, age, size, and health status. Regular physical activity not only keeps your dog fit but also enriches their life, reduces the likelihood of behavioural problems, and strengthens the bond you share with your furry friend. Always consult with a veterinarian to design an exercise program that’s tailored to your dog’s specific needs.
Treatment and Prevention of Dysbiosis in Dogs
Gut dysbiosis in dogs is a condition characterised by an imbalance in the gut microbiome. It can result from various factors, including diet, medications, stress, age, and underlying health conditions. Recognising the signs of gut dysbiosis and taking appropriate measures to address it, such as dietary modifications, probiotic supplementation, and stress reduction, can help restore a healthy balance in the gut microbiome and improve the overall health and well-being of your dog. Top of Form
- Diet Modification: A key approach to addressing gut dysbiosis is through dietary changes. Switching to a high-quality, balanced diet that supports gut health can help restore the microbiome’s balance. Consider incorporating probiotic-rich foods or supplements and prebiotic fibres to promote the growth of beneficial bacteria. (184)
- Probiotic and Enzyme Supplements: Probiotic supplements provide beneficial bacteria that can help restore the balance of the gut microbiome. These supplements introduce live cultures that can support a healthy gut environment. Digestive enzyme supplements can also aid in proper digestion and nutrient absorption. (185, 186)
- Minimising Stress: Minimising stress in a dog’s environment is crucial for maintaining a healthy gut microbiome. Provide a stable and calm environment, engage in regular exercise and mental stimulation, and ensure your dog feels safe and secure. (187, 188)
- Gradual Transitional Changes to Diet and Lifestyle: When introducing dietary or lifestyle changes, do so gradually to allow the dog’s digestive system to adapt and prevent further disruptions to the microbiome. Abrupt changes can cause digestive upset and exacerbate dysbiosis. The key to transitioning your dog to a new food is patience.
- Regular Veterinary Care: Regular veterinary check-ups are essential for monitoring your dog’s overall health, including the gut microbiome. Your veterinarian can provide guidance on specific dietary recommendations, supplementation, and any necessary medical treatments.
How Nutrition Contributes to Inflammation and Ageing
We are what we eat is accepted as a truism. What, and how much, we feed our dogs has a significant bearing on their health and wellbeing.
It is important to consider all the aspects of a dog’s diet and nutrition to understand how what we are feeding them may be detrimental to their health in both the short and long term.
Your dog’s nutritional health depends on receiving the correct amounts and proportions of nutrients from the six required groups: water, protein, fat, carbohydrate, minerals and vitamins. With the exception of water, commercial dog foods identified as 100% complete and balanced must contain all of these required nutrients.
Protein – Too Much Can Be Deadly
Protein is a very important part of a healthy, balanced dog’s diet. Protein has several roles in your dog’s body, such as building and repairing muscles and other body tissues. It is needed to form new skin cells, grow hair, build muscle tissue, and more. It also assists in creating body chemicals like hormones and enzymes that are needed for normal function. It provides energy (like carbohydrates and fats do) and keeps their immune system strong.
Proteins can be found in plants, algae, fungi and animals. Like us, dogs need nutrients not ingredients, to thrive physically and emotionally. Dogs are capable of digesting protein from a variety of sources and if they are getting the correct balance of amino acids from the protein they eat, they will thrive.
Many pet food manufacturers are including protein at levels that exceed our dog’s daily requirements, marketing them as high protein (greater than 30%) appealing to those who believe the more protein the better.
Unfortunately, these high protein foods could be harmful to both your dog’s health and the environment.
Dogs, like humans, can only use a certain amount of the protein that is digested and absorbed to repair and maintain muscles and other tissues. Any excess must be disposed of, which means it is broken down and burned for energy or stored as fat, and this fat can be very damaging to their health.
Overweight dogs are more likely to suffer from diabetes, heart disease and cancers as well as joint and mobility issues.
A study, Varying Protein Levels Influence Metabolomics and the Gut Microbiome in Healthy Adult Dogs, published in 2020 by Eden Ephraim et al found that consumption of high protein food over the long-term increases in metabolites associated with kidney dysfunction, inflammation, and proteolysis.
it’s not the amount of protein in a dog’s diet that is important, but the digestibility and bioavailability of amino acids. Often, high-protein, meat-based dog foods include protein sources that are neither highly digestible nor bioavailable to your dog. Unused protein ferments and goes into faecal matter, making your dog’s solid waste smellier. If you have yellow spots on your lawn, it is likely a result of excess amino acids from high protein foods that are excreted in your dog’s urine.
A medium protein dog food has a protein level between 21-29%, 25% being the mid-point and the level trialled in studies as a medium protein diet. This will provide your adult dog with all the amino acids it requires.
Carbohydrates – Unfairly Demonised
Carbohydrates, often misunderstood in dog nutrition, play a crucial role in a dog’s diet. Unlike their wolf ancestors, dogs have evolved to efficiently digest carbohydrates due to genetic adaptations. This evolution is marked by an increase in the amylase gene, responsible for starch digestion, where dogs possess significantly more copies than wolves, leading to a 2800% increase in gene activity in dogs (2, 6). Additionally, dogs have genetic variations in genes like MGAM, enhancing their ability to process carbohydrates into glucose efficiently (189, 190).
Nutritionally, carbohydrates are categorised into simple and complex forms. Simple carbohydrates, found in fruits and processed sugars, are quickly absorbed, potentially leading to rapid blood sugar spikes. On the other hand, complex carbohydrates, present in whole grains, legumes, and vegetables, contain longer sugar chains and fibre. This composition ensures a gradual absorption of glucose, providing a more stable energy supply and preventing sudden blood sugar spikes.
The glycaemic index (GI) and glycaemic load (GL) are key concepts in understanding a food’s impact on blood sugar levels. Foods with a high GI cause rapid increases in blood sugar, whereas those with a low GI lead to a slower, more controlled rise.
Foods with a high GI (higher than 70) are easily digested and cause a quick rise in blood sugar. Foods with a low GI (lower than 55) get digested more slowly and the blood sugar response is flatter.
Rice and maize (corn) have both been shown to increase the glycaemic response in dogs when compared with legumes such as peas, lentils, fava beans (191, 192)
The glycaemic load also accounts for the carbohydrate content in foods. Studies show that dogs respond to GI and GL in a manner similar to humans, affecting starch metabolism and blood sugar responses (193, 192, 194, 195, 196).
A diet with a low GI is beneficial for dogs, offering health advantages such as reduced insulin levels and resistance, better cholesterol balance, decreased risk of cardiovascular diseases and certain cancers, and lower abdominal fat (197, 198, 199). These benefits are particularly significant given the increasing prevalence of obesity, diabetes mellitus, and cardiovascular problems in dogs. Understanding and using GI and GL in choosing dog foods can significantly impact their health and longevity.
Fibre – The Forgotten Hero in Dog Food
Fibre, exclusively found in plants, is vital for many health aspects, including gut health and weight management. Not all fibres are the same, with some offering significant health benefits and others potentially causing digestive issues. In dogs, fibre is crucial as they lack enzymes to digest it, passing through their digestive system mostly unchanged.
Fibre is broadly categorised into two types (200):
- Dietary Fibre: Naturally found in foods.
- Functional Fibre: Extracted and added to processed foods.
However, this classification doesn’t reflect health effects. A more functional categorisation includes solubility (soluble vs. insoluble), viscosity, and fermentability.
- Soluble Fibre: Forms a gel-like substance in the gut, aiding in reducing blood sugar spikes and offering metabolic health benefits (201).
- Insoluble Fibre: Acts as a bulking agent, aiding in food and waste passage through the gut (202).
Fermentable fibres are crucial for gut health in dogs and humans, as they serve as prebiotics for gut bacteria, essential for weight management, blood sugar control, and mental health. These fibres increase friendly gut bacteria and produce beneficial short-chain fatty acids.
Viscous fibres, a type of soluble fibre, form a gel in the gut, slowing nutrient digestion and absorption, reducing appetite, and aiding in weight management (203).
Resistant starch, often considered a dietary fibre, resists digestion and functions like soluble, fermentable fibre in the gut. It offers multiple health benefits, including improved digestive health, insulin sensitivity, and appetite reduction (204, 205, 206, 207, 208, 209).
Specific fibres with notable health implications include:
- Fructans: Beneficial for gut bacteria but can cause digestive issues in sensitive individuals and dogs (28). The biggest source of fructans in the modern diet is wheat. Wheat is also one of the primary foods that causes digestive sensitivities in dogs.
- Beta-Glucans: Improve insulin sensitivity and cholesterol levels (210).
- Glucomannan: A viscous fibre used for weight loss and heart disease risk reduction.
Fibre’s role in dog health parallels its importance in human diets. It aids in digestion, managing healthy weight, supporting anal gland health, and improving diabetes management. Fibre ensures bowel regularity and helps dogs feel full with fewer calories, making it essential for weight management. Furthermore, it facilitates anal gland expression and stabilises blood sugar levels, beneficial for diabetic dogs.
Fats – The Good, The Bad and the Ugly
Fats are essential for dogs, offering numerous health benefits. They provide energy, support skin and coat health, aid nutrient absorption, transport fat-soluble vitamins (A, D, E, K), and are crucial for maintaining cellular integrity, nervous system, brain, liver, blood, hormone function, and regulating body temperature.
There are three primary types of fats: unsaturated, saturated, and trans fats. Unsaturated fats, typically from plants and seeds, and saturated fats, mostly found in animal products, are important for dogs. Trans fats, often resulting from food processing, are less common in nature.
Dogs require essential fatty acids (EFAs) that their bodies can’t produce, including Omega-6 fats (Linoleic acid, Arachidonic acid) and Omega-3 fats (Eicosapentaenoic acid – EPA, Docosahexaenoic acid – DHA, and Alpha-linolenic acid – ALA). Unsaturated fats can be further classified into monounsaturated and polyunsaturated fats (PUFAs), the latter providing many essential fatty acids.
Balancing saturated and unsaturated fats in a dog’s diet is crucial for optimal health. Fat digestion in dogs involves bile secretion from the gallbladder and enzyme release from the small intestine and pancreas. Excess fat, however, can lead to health issues like hyperlipidaemia, heart disease, and certain cancers.
Omega-6 fatty acids are essential for immune function, blood clotting, brain development, skin and hair growth, bone health, metabolism, and reproductive health. Omega-3 fatty acids are vital for cell membrane function, brain composition, and forming anti-inflammatory compounds.
Dogs inefficiently metabolise ALA from plant-based oils (e.g., flaxseed, rapeseed), making it less effective. Instead, EPA and DHA from sources like algae extract are more beneficial. Supplementing with EPA and DHA offers advantages for skin and coat health, cognitive function, heart health, and joint health. These fatty acids help in anti-inflammatory processes and improve cholesterol levels.
The inclusion of EPA and DHA in dog food, helps maintain this balance. The ideal Omega-6 to Omega-3 ratio for dogs is between 1:1 and 4:1.
Modern diets often have a high Omega-6 content due to intensive farming practices and animal feed compositions, mainly soy and corn, potentially leading to an inflammatory state. Balancing this ratio is key to supporting a healthy immune system and preventing chronic and autoimmune diseases, as well as inflammaging in dogs.
Vitamins and Minerals – Key Elements of Dog Nutrition
Minerals – Macro and Micro Both Are Vital
Minerals are vital for a dog’s health, with over 18 essential mineral elements needed. These include macrominerals (required in larger amounts) and microminerals or trace elements (needed in smaller quantities). Proper development and function of a dog’s body depend on these minerals in correct amounts in their diet.
Research by the University of Guelph indicates that plant-based dog foods may have similar or better digestibility of certain minerals (calcium, phosphorus, iron) compared to meat-based foods (4). Chelated minerals, which are organic forms of trace minerals like Copper, Iron, Manganese, Calcium, and Zinc, are better absorbed and utilised by dogs (211). These chelates, bound to amino acids, lead to lower excretion rates and reduced environmental contamination. In 2003, Europe legislated reduced feed concentrations of several trace metals due to environmental concerns (Co, Cu, Fe, Mn, Zn).
Chelation does not improve absorption rates for Calcium and Manganese, so their chelation is unnecessary.
Zinc is crucial for enzyme, protein, and hormone functions, immune and thyroid function. Deficiency can lead to infection vulnerability, abnormal iodine metabolism, and sexual dysfunction. Chelated Zinc is better absorbed (212, 213, 214).
Copper aids bone formation, nerve protection, and iron absorption, influencing coat colour and joint health. Chelated Copper is also better absorbed (212, 213) by dogs.
Iron, forming haemoglobin, is essential for oxygen transport and enzyme function. Iron deficiency can cause anaemia and growth issues. Natural Vitamin C sources.
Calcium is known for strong bones but also aids in digestion, blood clotting, muscle function, hormone release, and maintaining a regular heartbeat. Hypercalcaemia (calcium deficiency) can result from poor diets.
Manganese, vital for digesting proteins and carbohydrates, acts as a catalyst in enzymatic functions and bone formation. It’s an antioxidant, preventing harmful oxidation. Manganese deficiency is rare, but symptoms include poor growth and skeletal abnormalities. Chelated Manganese shows better absorption (212, 213).
Selenium, critical for immune system and thyroid gland functioning, has greater bioavailability in organoselenium compounds compared to inorganic forms (212). Selenium is noted for its anticancer, joint health, and antioxidant properties.
Vitamins – Fragility and Importance of Vital Nutrients
Vitamins are essential nutrients crucial for your dog’s growth, repair, and overall health, but an excess of certain vitamins can be harmful.
Dogs require both water-soluble and fat-soluble vitamins. Water-soluble vitamins (C and B-complex) are vital for bone, teeth, and connective tissue formation. Since they’re flushed out regularly, dogs need constant replenishment. Vitamin C is naturally produced by a dog’s body, and supplementation should only occur under veterinary guidance.
Fat-soluble vitamins (A, D, E, K) are absorbed through the intestine and stored for later use. Overaccumulation can cause physical abnormalities, especially in bones, so supplementation should be vet prescribed.
Vitamin A is vital for growth, vision, immune function, and organ health. While preformed vitamin A (from animal sources) can be toxic in excess, provitamin A (beta-carotene from plants) poses no overdose risk. Foods with high beta-carotene content reduces the need for added Vitamin A, lowering toxicity risks. Sources include sweet potatoes, carrots, and kale.
Vitamin D3 is crucial for muscle, nerve function, and calcium and phosphorus absorption. It’s essential for bone health and may influence cancer risk. Dogs can’t synthesise Vitamin D3 from sunlight and require dietary sources. Vitamin D3 (cholecalciferol) is preferred over D2 (ergocalciferol) for better calcifediol production, crucial for assessing vitamin D status (213, 214, 215).
Vitamin E, an antioxidant, supports the immune system, muscles, heart, liver, nerves, and skin.
Vitamin K is necessary for blood clotting and calcium metabolism. While most dogs produce enough Vitamin K internally, leafy greens like spinach provide natural sources.
Choline supports brain and liver function and is used in treating epilepsy.
Provitamins like Taurine and L-Carnitine are also crucial. Taurine supports heart health. L-Carnitine aids in energy production, and deficiency can lead to heart disease. Adequate L-Carnitine play an essential role in energy production and heart health (216, 217, 218, 219).
Vitamins, particularly the more heat sensitive vitamins, can be affected by heat extrusion processing reducing their levels and viability in dog food (220).
Food Quality – It’s All in the Cooking
Diet plays a crucial role in a pet’s health and wellbeing. Unfortunately, food processing methods, especially those altering the food from its raw state, can negatively impact its nutrient content. Extrusion, a common food manufacturing process used for various products including pet food, can particularly affect nutrient integrity.
Developed in the 1930s for dry pasta and breakfast cereals, extrusion technology expanded into pet food manufacturing by the 1950s. It simplifies texturisation, mixing, forming, and cooking of food. There are several types of extrusion processes: cold, hot, steam-induced, and co-extrusion. The basic process involves grinding dry ingredients, mixing with other components (vegetables, fruits, oils, fats, meat, or water), and then cooking through an extruder.
Around 95% of dry dog foods are processed using the ‘high temperature short time’ (HTST) extrusion method, heating ingredients to 110ºC-150ºC for 60-270 seconds (221, 222). This process can significantly impact nutrient integrity, especially for non-heat stable vitamins (B group, A, C, E) and requires manufacturers to add back excess vitamins (223). Minerals’ bioavailability may also be affected by heat (224). Essential fatty acids, like Omega 3, are sensitive to increased processing temperatures (225). Probiotics, beneficial for gut health, lose efficacy due to high heat (226). Additionally, high temperatures denature proteins and trigger the Maillard reaction, potentially forming harmful compounds like acrylamide and AGEs (advanced glycation end products).
The environmental impact of high-temperature cooking includes significant water and energy use, contributing to increased greenhouse gas emissions.
In contrast, cold extrusion, or cold pressed, uses lower temperatures (not exceeding 70ºC), preserving heat-sensitive ingredients like vitamins, minerals, omega-3s, phytonutrients, and probiotics. This method maintains nutritional integrity, minimises the need for synthetic nutrients, and results in lower lipid oxidation. It’s more environmentally friendly due to lower energy, water, and other inputs, reducing emissions. Additionally, cold extrusion allows for more ‘wet’ ingredients, enabling the inclusion of fresher components in the final food product.
