Nothing stirs a passionate debate among avid raw food feeders (and vets sometimes!) than the topic of feeding vegetables to your dog.
The staunch prey model enthusiasts say absolutely not – dogs are carnivores and can get all the nutrients they need from meat sources. Some conventional veterinarians advise pet owners not to feed their dogs “human foods” at all. Others uphold the idea that dogs are actually omnivores, able to feed on a wide variety of foods including grain, vegetables and fruits. At the other end of the spectrum, there are pet owners who choose to feed vegetarian or more extreme vegan diets to their dogs.
How do you decide with all this conflicting information and very little useful independent research on the topic to guide you?
I found the following considerations useful for helping my decision to add vegetables (and fruits) as a component of my dogs’ diet:
Dog ancestors’ eating habits
Despite the diverse range shapes and sizes of our dogs today – from the tiniest chihuahua to the regally giant Great Dane – they all fundamentally have the same physiological digestive tracts as that of their ancient wild dog ancestors (wolves, coyotes, jackals and foxes), who hunted prey as their main source of food. So does this mean because our dog’s ancestors were physiologically designed to eat meat, that’s all we should feed our dog’s today?
If we look to current wild dog populations, who continue to share the same digestive physiology of our dogs, they are considered scavenging or opportunistic carnivores, which means they would prefer to eat prey first and foremost when they could, but in lean times, could survive by scavenging other food sources, including fruits and plants matter.
Another way they may have consumed plant matter is through the contents of the herbivorous prey they caught. And so their digestive systems were able to assimilate and make use of these foods to help sustain them. As with our domestic dogs, they produce the enzyme amylase, which helps digest starch, in their pancreas (as opposed to the mouth as in humans).
If our dogs were able to consume whole wild prey on a regular basis like their ancestors, (bones, meat, organs, skin, fur etc) they would likely have a greater chance of consuming a more nutritionally optimal diet. Important minerals such as manganese, copper, iron and zinc, vitamins and fatty acids are mainly contained in the organs and glands of animals, while fur and feathers are a valuable source of fibre. For most of us wanting to feed fresh foods though, it is neither practical nor sustainable to feed our dogs whole prey, so we turn to the agricultural alternatives more readily available to us to try and mimic some of these components of prey.
Changes in our environment and the food chain
Modern food production methods for both domestic livestock and agricultural crops tend to have significantly lower nutritional values compared with their wild counterparts. This is due to a combination of factors including soil degradation, genetic selection for higher yields and disease resistance, pesticides and decreasing bio-diversity.
While many vegetables and fruits produced through modern methods are also likely to have suffered some reduced nutritional value, when combined with a good mix of meat sources, can supply a unique composition of vitamins, minerals and fibre that complement a pet’s diet. Fruits and vegetables are also the only main source of anti-oxidants, which are important to help combat the effects of modern urban living that can lead to disease and ill-health in our dogs. Other fruits such as pineapple contain enzymes that can support good digestion.
Those who choose to feed their dog dry or other processed foods can also add a great source of additional whole food nutrients by adding vegetables and fruits to their dog’s diet.
What about vegetarian or vegan diets?
I know anecdotally of a number of dogs that have lived well on a vegetarian diet. Apparently one of the longest living dogs in the Guinness Book of Records was a Border Collie called Bramble in the UK, who lived to 27 years old on a diet of grains, legumes and vegetables. Of course, it’s unclear from much of the information about dogs like Bramble if they were fed that diet their whole lives, whether they may have had access to hunt their own small prey without the knowledge of their owners, or if their genetic composition was in fact more resilient than most other dogs to eating a vegetation based diet.
It seems possible for some dogs to do really well on a vegetarian diet, particularly if it is mainly composed of fresh ingredients with the correct nutrient mix, and is prepared to maximise the nutrient extraction (which to do properly would require a lot of work and effort to ensure it is delivering the appropriate levels of nutrition). But until there is some sound, longitudinal research to compare the relative impacts on health from a meat based versus a vegetarian or vegan diet, I cannot wholeheartedly recommend these diets for most dogs (and definitely not for cats), even though I philosophically prefer not to eat most types of meat myself.
Vegetables and fruits your dog shouldn’t have
While some take an extreme view about giving dogs any vegetables and fruits, suggesting they are either unnecessary, to the other extreme of being downright toxic, I am yet to see any compelling research to support either of the views. There are certain vegetables and fruits however that have been shown to be unsuitable for dogs causing anything from mild digestive upset to seizures and organ failure in extreme cases. These include:
- Onions – can cause anaemia
- Grapes – have caused toxicity to some dogs
- Fruit pips and seeds – can become lodged and contain some toxic substances
Others in contention as being beneficial or harmful are:
- Garlic – part of the onion family. However some contend small amounts offer more health benefits than the risk of anaemia.
- Mushrooms – some believe all mushrooms are toxic but they can be a great source of vitamins and minerals and some mushroom varieties have strong medicinal properties. The general rule is, don’t feed wild mushrooms or those that you are not sure are suitable for human consumption.
- Pomegranates and citrus – not considered poisonous but could cause stomach upset in some dogs. If your dog tolerates them well, they offer a great source of vitamins and antioxidants.
- Avocados – the stone and skin are toxic but there are mixed views and myths about feeding the flesh of an avocado. A study funded my Proctor and Gamble in 2012 found that avocado flesh is safe to feed to dogs; the leaves, bark, skin and pit should not be fed as they are toxic.
I personally feed occasional small doses of garlic, market bought mushrooms (although my dogs are so keen on them!), pomegranate and citrus as my dogs seem to do well on them, but err on the side of caution with other contentious foods.
My fruit and vegetable additions
I have found a small proportion of vegetables and fruits used as whole food supplements work well for my dogs, and I prefer to add them rather than rely on extracted or synthetic vitamin supplements. These comprise about 5% of my dog’s meal on average and I usually focus on nutrient dense leafy greens or culinary herbs rather than starchy vegetables and on the fruit side, berries feature most prominently. Spouts are also an excellent source of nutrients. My ultimate addition though is my homemade fermented vegetables, packing an extra probiotic punch for great gut health.
If you’ve made the decision to include vegetables and fruits in your dog’s diet, my next blog will explain what vegetables and fruits to include from your dog’s diet, the ideal proportions and how to prepare them so your dog can extract the maximum benefits these life enhancing foods offer.
Here are some of the books and papers I’ve found useful to help shape my views on this topic:
Bailey, S (2008), The Naturally Healthy Dog; Real Dogs Don’t Eat Kibble, Creative Genius, USA.
Billinghurst, Dr I (1993) Give Your Dog A Bone, 10th Print, Billinghurst Australia.
Brown, S (2010), Unlocking the Canine Ancestral Diet, Dogwise, USA.
Davis, D et al (2004), Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999, MD Journal of the American College of Nutrition, Vol. 23, No. 6, 669–682 Published by the American College of Nutrition
Middle, Dr C (2008), Real Food for Dogs & Cats, Fremantle Press, Australia.
Olsen, L (2010), Raw & Natural Nutrition for Dogs, North Atlantic Books, USA.
Pitcairn, Dr R & Pitcairn, S (2005), Complete Guide to Natural Health for Dogs & Cats, Rodale, USA.
Schultze, K (1998), Natural Nutrition for Dogs and Cats – The Ultimate Diet, Hay House, USA.
Taylor, B & Becker, K (2009), Dr Becker’s Real Food for Healthy Dogs & Cats, Natural Pet Productions, USA.
Wakefield L, Shofer F, Michel K (2006) “Evaluation of cats fed vegetarian diets and attitudes of their caregivers”, JAVMA, Vol 229, No. 1, July