Why Man is Man’s Best Friend’s Worst Enemy: Dog Food & Human Disease

For thousands of years, dogs have been evolving by our side. From the wild plains of Siberia to bustling cities, their bond with humans has only strengthened. Yet, as our lifestyles have changed, so too have the diets of our loyal friends. Long gone are the days when dogs scavenged alongside us for scraps of meat or hunted in packs for survival. Today, many dogs are fed ultra-processed kibble, often packed with fillers, preservatives, and unnecessary carbohydrates. This shift raises an important question: Are we, in our quest for convenience, inadvertently harming our best friends? With obesity and diet-related diseases on the rise among dogs, it’s time to consider a more natural, evolutionarily consistent approach to their nutrition.

Domestication

A literature review of ancient DNA evidence suggests that dogs were domesticated in Siberia around 23,000 years ago and migrated with humans into the Americas about 15,000 years ago (1). This range aligns with the consensus amongst zooarchaeologists that dogs were domesticated well before the advent of agriculture (2). Agriculture is believed to have begun roughly 12000 years ago, suggesting the natural diet of dogs did not include any man-made crops.   

Pet Food and Disease

Much like the rise of ultra-processed foods for humans, which often use low-cost, waste materials like cottonseeds and sawdust, dog food has followed a similar trajectory. The first commercial dog food was developed in 1860 by an industrious businessman named James Spratt. He observed dogs eating leftover biscuits from ships and decided to formulate his own dog biscuits from food waste products. The model took off and was particularly popular during the great depression, as owners couldn’t afford to feed their dogs real food.

Since then the ultra-processed pet food market has taken off, with the global pet food market valued at USD 120.87 Billion in 2023. It is crucial to consider how these financial incentives might impact the literature and veterinary industry, potentially leading to the promotion of ultra-processed pet foods rich in carbohydrates and seed oils, while condemning raw meat and bones. The shift from a natural diet has led to the development of human diseases like obesity and diabetes being commonplace amongst dogs. The human obesity epidemic is paralleled among dogs, with an estimated 56% of U.S. dogs being overweight or obese (3). This suggests that ultra-processed diets contribute to similar health issues in both humans and dogs.

What Do Dogs Eat?

Dogs are facultative carnivores and scavengers by nature. Their diet in the wild would consist of a mix of animal protein, fat, and whatever they could scavenge. Dogs have unspecialised dentition and diverse feeding behaviours, which is reflective of their genus Canis. Their dietary behaviours extract elements from both their pack-hunting ancestor (wolf) and the significant intraspecific diversity developed through long-term domestication (4).

A 2017 self-selection, ad libitum (eat-to-satiety) study investigating macronutrient preferences amongst dogs found that when given a choice, dogs initially prefer energy-dense fat over protein, reflecting a "feast or famine" mentality inherited from their wolf ancestors. Over time, their intake shifts to a more balanced diet, increasing protein consumption while minimising carbohydrate intake, suggesting that dogs naturally avoid carbs as a significant dietary component (5). These findings are notable as most dog foods are loaded with carbohydrates, a nutrient that they instinctively would avoid. Further, the tendency to limit fat after the feast instinct has subsided, suggests that a higher protein diet is preferable over high fat.

Ketosis

Ketosis is a metabolic state in which the body uses fat, rather than carbohydrates, as its primary energy source, leading to the production of ketones in the liver. Ketosis may be a natural metabolic state for dogs, similar to humans. In the wild or during early domestication, dogs may have gone days without eating. During times of famine or migration, humans would have had little to feed them so meals would have been scarce.

Short-term feeding of a ketogenic diet in dogs may alter the metabolome toward an anti-tumorigenic (counteract tumour formation) profile, which could support the treatment of cancer (6). Ketogenic diets have also been shown to assist in the treatment of epilepsy, which is the most common neurological disorder in dogs (7). Consistent feeding schedules do not reflect natural feeding behaviours. Therefore, there may be value in being inconsistent.

The Ideal Diet for Dogs

The modern ultra-processed dog food diet has strayed far from an evolutionarily consistent diet. Due to the observed health issues plaguing modern dogs, raw meat-based diets (RMBDs) are gaining popularity. One study comparing RMBDs and kibble found that dogs fed a RMBD had a 50% lower serum alkaline phosphatase (ALP) activity and showed modest improvements in skin, dental, and overall clinical health compared to kibble-fed dogs, with faecal consistency also being firmer in RMBD-fed dogs (8).

The BARF (Biologically Appropriate Raw Food) diet, developed by Dr. Ian Billinghurst, advocates feeding dogs raw, unprocessed foods that mimic what their ancestors would have eaten in the wild. This diet includes:

• Raw meat: For protein, micronutrients and fat for energy.

• Raw bones: For bioavailable calcium, phosphorous, collagen and many other nutrients. Plus the mental health benefits and benefits for the jaw and teeth.

• Organs: Rich in essential nutrients.

• Fruits and vegetables: A small portion to mimic the stomach contents of prey animals, preferably fermented.

Proponents of the BARF diet claim it leads to better digestion, cleaner teeth, shinier coats, and stronger immune systems. It's important to consider concerns such as bacterial contamination risks (e.g., Salmonella, E. coli), nutritional imbalances, and potential choking or dental hazards from bones. Careful planning and strict hygiene are essential for safely feeding RMBDs.

Final Thought

In the world of food science, there is no money to be made eating whole foods. The profit comes from turning waste and scraps into a valuable product with margins. The pet food industry is no different, there is a vested interest in pushing ultra-processed kibble. Dogs need food that aligns with their evolutionary history, not chemically engineered products. The best diet for dogs may not be kibble or high-end steaks, but a variety of raw foods they have evolved to derive nutrients from.