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Foods You Should Never Feed Your Dog

Many common human foods are toxic to dogs and can cause severe illness or even death; for example, chocolate and grapes are inherently unsafe for canine consumption. While these obviously dangerous foods are easy to identify and avoid feeding dogs, some ingredients that appear innocuous and healthy actually create issues at a cellular level when consumed by canines. These problematic ingredients masquerade as functional foods for dogs when in fact they should also be avoided.

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Foods that are never functional for dogs include:

  • Alcohol

  • Chocolate

  • Coffee, tea & cola – any caffeine products

  • Grapes and raisins/sultanas

  • All onions, including leeks and shallots but excluding garlic, which is very good in small amounts

  • Xylitol (artificial sweetener)

  • Spoiled or mouldy foods contain toxins that can cause severe gastrointestinal upset


Stay away from high glycaemic carbohydrates

The Glycemic Index (GI) ranks carbohydrates based on their effect on blood sugar levels. High GI foods cause the body to produce chronic inflammation, which can contribute to health problems like obesity, diabetes, heart disease, arthritis, and cancer.

Avoid feeding your dog these high-glycaemic carbs:

  • Corn

  • Sugar

  • Wheat

  • White rice


You’ll notice that these ingredients are commonly found in commercial pet foods.  Instead of feeding your dog these high-GI carbs, try adding some functional carbs to its bowl.  See my article on functional foods.


Food that causes sensitivity/intolerance

Many dogs develop food intolerances or sensitivities from eating low-quality commercial dog food daily, which can cause gastrointestinal issues like leaky gut syndrome that disrupt the immune system. Foods that provoke adverse reactions in a dog are not considered ‘functional’. The most common problem foods are:


  • Beef

  • Chicken

  • Corn

  • Cows milk products

  • Soy

  • Wheat


You’ll notice that most of these ingredients are commonly found in many mass-market, commercial foods. This is because they are cheap to produce. Dogs fed the same diet over many months and years can develop an intolerance to the proteins within, which can cause them to suffer needlessly.

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Cut back on Corn consumption

Corn, a highly cultivated genetically engineered crop, is a prevalent ingredient in commercial pet food.  It is unsuitable for dogs because they lack the enzymes to digest it properly. As carnivores, dogs are not biologically adapted to process plant foods like corn efficiently. Filler ingredients like corn in processed dog foods can cause inflammation, allergies, and other health issues.  It is also a major cause of food sensitivities and obesity due to its high glycemic index rating.

Is Wheat protein making your dog sick?

Wheat contains gluten, a protein linked to serious health issues in both humans and dogs. Some dogs, like Irish Setters, are genetically intolerant to gluten, suffering gas, bloating, diarrhea, and more severe problems. However, all dogs can experience harmful inflammation from gluten, potentially causing disease in every organ, brain inflammation, and age-related dementia.  Eliminating wheat and its inflammatory gluten protein can greatly benefit a dog's health.

The controversy with soy

Soy is commonly used in dog food as a cheap source of protein. However, soy is not biologically suitable for dogs and can cause various health issues. Soy is a common dog allergen and can lead to skin, digestive, and even thyroid problems. Additionally, soy contains high levels of phytoestrogens, which can disrupt hormonal balance in dogs.

This is definitely a controversial ingredient in dog foods, as there are conflicting studies for and against its benefits.  After reviewing the research on soy, I believe that the key to enjoying it as part of a healthy, balanced diet hinges on three key factors:

  1. Consuming it in moderation

  2. Steer clear of genetically modified soybeans

  3. Avoid it in the most highly processed forms, as seen in most commercial pet foods


Cows milk may get your dog moooving

Cows' milk is unsuitable as a primary ingredient in dog food, since most dogs are lactose intolerant and cannot properly digest lactose, the sugar in milk. Feeding dogs cow's milk or dog food containing it often leads to digestive issues like diarrhea and gas. While some dog foods may have small amounts of milk products, it is best to choose formulations made specifically for canine nutritional needs without cow's milk. The one nutritious exception is probiotic yogurt and kefir made from cow's milk, which are very low in lactose and can be fed in small quantities without adverse effects.

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Some food additives are not welcome

While some dog foods may contain additives, therefore choosing products that use natural and beneficial additives is important. Not all additives are harmful, and some can provide nutritional benefits to dogs. However, it is crucial to read the ingredient list and choose dog foods that prioritise real, whole ingredients over artificial additives. Look for dog foods that use natural preservatives like vitamin E instead of chemical preservatives. Additionally, avoid dog foods that contain artificial colours, flavours, or fillers. Opt for dog foods that are transparent about their ingredients and sourcing practices.


It is important to note that the focus should be on providing dogs with biologically appropriate, fresh, and species-appropriate diets. Non-functional foods, such as heavily processed dry kibble or vegetarian/vegan pet foods, may not meet the nutritional needs of dogs. These diets often lack essential bioactive compounds found in animal-based ingredients that dogs have evolved to require. It is crucial to prioritise real, whole ingredients and avoid ultra-processed foods that may contain allergens, chemicals, and low-quality ingredients. Feeding a balanced, fresh/raw diet is generally considered the best approach for optimal canine nutrition.

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