Carbohydrate in dog food

Which carbohydrate foods are best suited for dogs? Should dogs eat wheat? Can dogs digest corn? Should dogs eat grains at all? Lets try to answer these questions by taking a closer look at carbohydrate in dog food.

It is thought that the ancestors of our domesticated dogs were feral or semi-domesticated scavengers, living alongside man for tens of thousands of years after divergence from their wolf forebears. Over that time period, they have adapted to share our food – and more recently – the food that we make specifically for them. Archaeological remains suggest that humans have been eating grains as part of their diet for all of that time; long before we began to cultivate grains around 12,000 years ago.

Genetic researchers have studied the genes that code for the enzymes amylase and maltase (both key players in the digestion of starchy grains) and found differences that indicate that dogs are likely to be around 5 times more able to digest carbohydrate in their diet than wolves. This is because living alongside humans created an environment where the dogs who digested starches more efficiently, were more likely to thrive, reproduce successfully and spread their genes.

However, while dogs can digest carbohydrate to a degree we need to be clear as to what this does and does not mean.

• Not all dogs have the same capacity to digest carbohydrates, and in one study, in some of the individuals tested, the ability to produce amylase was quite limited. This means that the nutrition those dogs can get from carbohydrates is restricted.
• Some dogs are intolerant of some grains, which can have a negative impact and cause symptoms such as diarrhoea.
• An ability to digest some carbohydrates, doesn’t mean that a dog can thrive on a high carbohydrate diet. Dogs are non-obligate carnivores rather than omnivores. Their digestive systems are predominantly developed to process animal tissue, but they have adapted (to varying degrees), to be able to glean some nutrition from plants.
• Not all carbohydrates are equally easy to digest. The nutrients in foods such as rice, potatoes and tapioca are more readily digested than in grains like wheat and corn.
• Sometimes the carbohydrate in dog food has been chosen primarily to keep costs down, rather than for digestibility. If this wasn’t true, all dog foods would contain the carbohydrates that are easier to digest (and cause less sensitivity problems), such as rice.
• Some indigestible fibre is useful to aid the digestive process in dogs, just as it is in humans.

So, how do we apply this to our 21st century dogs’ diet? Remember the ingredients lists we considered in part one of this series? To recap, the ingredients are listed in order of how much of a component is included in the feed, for example, if wheat is the first ingredient on the list, then there is more wheat in the feed than any other ingredient. It is widely considered beneficial to a dog if their food has meat (including fish) as a primary ingredient, or at the very least, a readily digestible carbohydrate, such as rice or potato.

Dogs with food sensitivities and intolerances will almost always benefit from a diet that is meat (usually poultry or fish) based, with rice, potato or tapioca and no added wheat or corn.

An easily digested diet will not produce large quantities of waste. It has been very educational for me to work with dogs on a raw food diet, as they usually pass small amounts of formed, inoffensive faeces and not as frequently as those on dry kibble. Their diet does not contain ‘fillers’ that remain undigested and pass out the other end.

Feeds also have indigestible carbohydrate (fibre) added to aid digestion. This will be discussed fully in another post.

Julio Mercader et al; Science, Dec 18, 2009. Mozambican grass seed consumption during the Middle Stone Age.

E.A. Ostrander, R.K. Wayne: : Genome Res 2005. 15: 1706-1716. The Canine Genome.