Corn in dog & cat food: a nutritious grain or problematic filler? It’s an important question to ask yourself when choosing the best diet for your pet, and based on the title of this post, you probably already know on which side I stand. Please do read on, and I’ll let you in on the reasons I personally don’t feed Tonks & Ruby, my pets, foods with corn in them…
First, let’s talk about cats and corn:
I’ll keep it short and sweet: cats CANNOT digest corn, so don’t feed it to them. Alright, moving on to dogs… just kidding! I won’t keep it that short…
Cats are obligate carnivores, meaning that they eat only meat not by choice, but by necessity. While dogs, and even foxes, are actually omnivores and can derive value from non meat sources, at some point millions of years ago, our house cats’ ancestors lost that ability. Cats now, from lions and tigers to that little ball of fluff napping on your couch, are specialized meat eaters, and need way more protein than dogs do, because they get the majority of their nutrients and energy from meat based protein. Cats can metabolize fats and get energy from them of course, but that too must come from animal sources. All of this means that while corn (and other carbohydrates) may be fairly high in protein and vitamin/mineral content, cats cannot effectively digest and glean any value from them. Corn specifically spikes blood sugar, causes organ stress, and uses up your cat’s precious energy with absolutely no payoff.
Now, for dogs, it’s a bit more complicated, so I’ll break it down into points:
Dogs can technically digest corn, as they can function as omnivores, but it isn’t exactly easy for them. Dog food manufacturers try to help them out by grinding the corn before it’s cooked into the kibble; and the more finely ground it is, the more digestible it is. At the same time though: the more finely ground corn is, the higher its Glycemic Index. Therefore, the easier it is for dogs to digest, the worse it is for their blood sugar.
While corn does have some measurable biological value for dogs, it is pretty darn low. The proteins in corn are not particularly usable to dogs, it is a vitamin and mineral deficient foodstuff, and it doesn’t provide a significant amount of digestible energy.
Corn is not a common allergen for dogs, this is true; but it absolutely causes or exacerbates other allergies. Grain bins that corn is stored in after harvest are rife with dust, mites, and other contaminants. Even if the corn is thoroughly cleaned before grinding, the worst parts of these unwelcome additions can be absorbed into the grain before cleaning and still make their way into the kibble.
We’ve established that dogs can function as omnivores, so they can glean nutritional value from plant matter, but they do still need to get most of their protein, vitamins, and fat from meat. Commercial kibbles that do not get the majority of their protein content from animal sources (& this is most of them, yes, even Science Diet, and yes, even if meat is the first ingredient on the list) are not providing biologically appropriate and useful nutrition for your dog.
So why do we see corn as a major ingredient in so many dog and cat foods? And see commercial kibble companies putting out statements and articles touting the “benefits” of corn? Simply put: corn is cheap. It’s an inexpensive filler that raises those little percentages on the back of the bag. Adding corn makes the percentages on the label look good to consumers, even if the pets eating the food won’t gain any real nutritional value from those higher numbers.
For me and Tonks & Ruby corn just isn’t worth the risk. There are so so many other foods to feed your pets. Fresh is best, but even if kibble is the best option for your family, there are plenty of corn free, and grain free, options available. If you're looking to get corn out of your pets' diets, I’d love to talk to you about that and answer any questions you may have. You can contact me any time using the form on the homepage.
Originally Posted, by me, in 2018