This article was updated on November, 3rd 2013 to include additional information and studies
Nothing is more perplexing to pet parents researching raw diets or new raw feeders than the great debate over fruits and veggies in a dog’s diet. Once the decision to feed a raw diet has been made, most people are completely overwhelmed by all the conflicting viewpoints on carbohydrates.
The general public is quickly realizing that grains are not a healthful addition to a dog’s diet. This is something that most, if not all, knowledgeable raw feeders have known for some time and it’s great to see the pet food companies adapting to this. However, there’s more to the carbohydrate puzzle besides grains.
Fruits and vegetables are also carbohydrates and this is where some raw feeding ideologies take different paths. Some commercial raw pet food companies and BARF feeders believe that fruits and vegetables belong in a dog’s diet. On the other paw, Prey Model feeders advocate that as true carnivores, dogs have no need for plant matter and it isn’t a biologically appropriate food.
How do we get to the bottom of this ongoing argument? They may never be a clear victor in this great debate but we can analyze a carnivore’s natural diet in addition to their anatomy and physiology to made some educated inferences. Some of this information can be found in the Canine Evolution and Anatomy page. But, let’s recap some of the reasons that support the idea that dog’s don’t require carbohydrates (i.e. grains, fruits and vegetables).
What’s the Natural Diet for a Carnivore?
Most people are aware of a typical carnivore’s diet. Carnivores survive on other animals – more specifically, the muscle meat, bone, organs, connective tissue, fat, skin, and hide of its prey.
However, when it comes to domesticated carnivores, the vast majority of people have a different set of beliefs. Because cats and dogs have been surviving on grains, fruits, and vegetables in addition to meat, many people claim that their natural diet also included this type of food and they’re equipped to handle it.
In fact, many argue that a change in diet fueled the domestication from wolf to dog. They believed this occurred when wolves had a reduced need to hunt and began hanging around the permanent settlements of man, scavenging for food.
For example, wolves eat the muscle meat, fat, skin, hide, fur, and organs of their prey. They also eat some bone, depending on the size of the animal. Smaller, more pliable bones are crushed and swallowed. However, wolves don’t generally eat weight-bearing bones of large prey (i.e. leg bones on deer and other large mammals) because their too dense to crush through. This is why when you see pictures of wolves or other carnivores feeding, most of the inner body cavity is eaten with large bones and other parts remaining.
What About the Stomach Contents of a Wolf’s Prey?
To support the theory that wolves and domesticated dogs require plant matter, many people claim that wolves eat the partially digested stomach contents of their herbivorous prey, and therefore, do need plant matter for optimal health. In my opinion, it’s just a claim to help support the current industry’s practices of feeding carbohydrates.
When it comes to the stomach contents, the answer is – well, it depends. If a wolf was to catch something small, similar to the size of a squirrel, they’ll most likely eat it whole. So, yes, in this circumstance the stomach and it’s contents would be consumed.
What about the rest of the time, when a wolf catches much larger prey? According to leading wolf researcher David L. Mech who is a senior scientist with the Biological Resource Division and U.S. Geological Survey, wolves do not eat stomach contents. Mech has been studying wolves and their prey since 1958, and is quoted saying, “the vegetation in the intestinal tract is of no interest to the wolves” in his book Wolves:Behavior, Ecology, and Conservation. He also goes on to say, “The wolf’s diet consists mostly of muscle meat and fatty tissue from various animals. Heart, lung, liver and other internal organs are eaten. Bones are crushed to get at the marrow, and bone fragments are eaten as well. Even the hair and skin are sometimes consumed. The only part consistently ignored is the stomach and it’s contents.” You can find more quotes on the diet of wolves and the role stomach contents play by reading Dr. Mech’s books. You can also find more quotes from David L Mech here.
Other wolf researchers have confirmed the same finding, that wolves generally avoid the stomach contents and intestines of their prey animals.
Anatomical and Physiological Traits of Carnivores
We can garner that dogs were designed to eat meat by comparing their anatomy and physiology to their carnivorous relatives.
If you were to study other carnivores in the wild (lions, tigers, wolves, etc.). You’ll notice they too only eat meat. No other carnivore in a natural setting has a need for plant matter. If no other carnivore in the animal kingdom needs grains, fruits, or vegetables to be in optimal condition, then why do our dogs? Dogs come equipped with essentially the same anatomy and physiology as their wolf counterparts (remember they differ genetically by 0.2%) which should prove that just as their carnivorous relatives, our dog’s were NOT meant to eat grains, fruits or vegetables.
Teeth are specialized tools that we’re all equipped with. More importantly, they’re structured for the natural diet of the animal. Dogs lack flat molars, which are used for grinding, plant matter. Many herbivores (cows, deer) and omnivores (bears, humans) have these flat back molars. Instead, carnivores have sharp, pointy carnassial teeth in place of traditional molars. All the teeth in a carnivore’s mouth are set in a scissors bite. This is why carnivores are capable of crushing bones, ripping, shredding, and tearing through muscle meat.
Dogs, in addition to other carnivorous mammals also have powerful jaw and neck muscles compared to other animals. These assist in catching and eating prey. Once they grab hold of their prety, their strong muscles allow them to stay latched on while pulling down a prey animal and making the kill. Their muscles allow them to crush through bone and tear meat.
In fact, their strong jaws hinge open, allowing them to swallow big pieces of meat and bone. Their jaws cannot move side to side, only up and down. Because of these characteristics, carnivores have heavy skulls. They also possess sharp claws and powerful, muscular bodies that allow them to chase and effectively take down prey.
Dogs have elastic stomachs designed to stretch and accommodate large amounts of meat, bones, organs and hide – which is much more dense and heavy than plant matter. With short intestines and a short colon, food is able to pass through a carnivore’s digestive system quickly.
In contrast, the intestines of an omnivore or herbivore are longer to accommodate the fermentation times required when digesting carbohydrates. In a carnivore, plant matter is expelled quickly, before it can be fully digested and the vitamins and minerals can be absorbed because of their short digestive tract. This is EXACTLY why many BARF feeders puree their fruits and veggies before serving them to their dogs.
Carnivores also lack salivary amylase, the enzyme necessary for beginning the break down of carbs and starches before they enter the stomach. It’s responsible for the majority of starch digestion. Herbivorous and omnivorous animals produce amylase in their salivary glands, carnivores do not. Carnivores also lack the specific bacteria that aids in the break down of cellulose and starch. Because of the difference in their digestive systems, dogs cannot properly break down and assimilate the nutrients from plant matter before they’re digested and expelled from the body. This is why commercial pet food manufacturers often add vitamins and mineral back to the food (that and because cooking destroys valuable enzymes and reducing vitamins and minerals).
What About All The Studies?
What about all the scientific studies suggesting that dogs are capable of handling starchy carbohydrates? There are many studies out there that attempt to prove dogs can digest grains, fruits, and vegetables. However, their findings are just one small piece to the puzzle, not concrete evidence that dogs can handle this type of diet without negative health effects down the line.
A summary of one in particular concludes that a dog’s digestive system is “geared up for rice and potatoes.” The study compared dog and wolf DNA with the hopes of finding clues about which genes drove dog domestication. About half of them had to do with the brain which isn’t surprising since dogs became more comfortable, social and submissive around man.
The other half had to do with digestion. It found that dogs had significantly more copies of the gene for amylase compared to their wolf counterparts, therefore meaning dogs are better at handling starch. They found this to be true in varying populations of humans as well. Those from Japanese and European cultures had more copies for the gene than did people with low starch diets such as those in Mbuti, Africa. It also found that dogs carry extra copies and longer versions of another gene that codes for maltase, another enzyme helpful in starch break down.
What Does This Tell Us?
It merely states a fact: dogs have more copies of these particular genes. Yet, the issue is more complex and not quite so cut and dry. If there was a comparative study showing the health differences between naturally reared, raw fed dogs compared to dogs fed grains fruits or vegetables, the results would be eye opening.
Dogs needed to evolve with the extra copies of these genes to survive. As dogs lingered in the more permanent settlements of early man and scavenged for food, natural selection occurred. Remember, dogs are opportunistic carnivores and scavenging was easier and safer than competing with other carnivores for food. The early wolves or wild dogs that tolerated starches and carbohydrates the best survived, and over time evolved to have extra copies of the genes, passing those on to subsequent generations. The dogs that were able to handle this type of food survived and went on to reproduce, whole those that couldn’t, did not survive.
We’re aware that dogs and wolves, though still sharing an almost identical genetic blueprint, do in fact, have differences. But what we need to remember, is just because dogs are surviving on a new food – a food that was not biologically appropriate or natural to them – doesn’t mean they are thriving on this new type of food. Too much emphasis is put on whether or not an animal can survive on something, not if it’s optimal for good health.
Because dogs lack salivary amylase, their bodies produce it later in digestion. Herbivores and omnivores produce it in their saliva and it gets to work breaking down the starch and carbs before it enters the stomach. Then it goes through the much longer and more complicated digestive tract of these animals where there’s time for the food to be fully digested and the nutrients absorbed.
In a carnivore’s digestive system, breakdown of these foods doesn’t start until the food reaches the pancreas and intestines. And because we know how short a carnivore’s intestine are, the food will be eliminated before it’s fully digested, meaning the animal isn’t able to absorb the nutrients and benefit from the food completely. It keeps them alive but dogs on diets high in carbs have compromised immune systems and suffer over time leaving room for illness and disease. This is evident by all the chronically sick pets today.
What Else Can We Conclude From These Studies?
I approach studies with caution. It’s not that the facts are wrong by any means but the big picture still needs to be analyzed. For example, is there evidence that dogs cannot handle grains? I’d say so from the vast amount of pet food that is grain free and the testimonials from pet owners and veterinarians on the healthful changes in their dogs once grain free. In my opinion, this indicates there’s a lot more to this puzzle. The study didn’t crack the case.
Also, it’s always worth looking into who funded the study. Studies today are not void of bias and those conducting the research often have a vested stake in the outcome. For more reasons why I’m cautious of such findings, read my “5 Questions to Ask Yourself When Reading Anti Raw Articles” post. If it’s a company, do you know what they do, do you know who owns them – all questions to consider at least.
If you’ve examined and made assumptions about who funded it, it’s also important to look at the statements made and ask yourself if the individual is an expert on the subject or is qualified to make such statements with sheer certainty. This particular study was trying to discover more information on DNA changes in the hopes of uncovering the mysteries about the evolution of dogs. One evolutionary biologist, who was not involved with the work, said “he gets contacted often by pet owners wondering if dogs like wolves, should eat primarily meat.” He was quoted saying, “This study suggests no, dogs are different from wolves and don’t need a wolflike diet. They have coevovled with humans and their diet.”
Though this man is an authority in evolutionary science, he’s merely stating an opinion that’s based on the research – nothing wrong with that. Again, I’d take all the accounts of sick pets, food allergies, and an entire industry shifting away from dog food with certain ingredients as a testament that his statement may not be entirely accurate (or there’s more to the story at least). Everything about a dog’s anatomy, physiology, and genetic code are striking similar to wolves – and far more different from humans. So in my opinion, comparing them to us nutritionally, is not the best course.
The bottom line is a lot of these studies exist – whether sponsored by companies and businesses in the pet food industry or organizations with no ties to the pet food industry whatsoever. Always look at the big picture. I form my own opinions by judging the sentiment and emotion around such studies and use that as an indicator.
Check out some of these articles, like this one for example, and view the comments. It’s hard for me to reasonably believe that this isn’t an article using recent scientific research as an aim to improve the reputation of the pet food industry and the health of their products.
The aforementioned article’s purpose was uncovering clues about evolution. It’s interesting to me that there are so many heated people, clearly bothered and ready to discredit valid points, theories or ideas from raw feeders. I think evolutionary scientists have way more important things to worry about than what raw feeders think of their studies (but that’s just my opinion).
I think these articles are more often than not used to support the views of opponents to raw feeding practices. Somehow simple facts from these studies get turned into concrete answers in canine nutritional debates where the topic is so much more complex. They become the proof or ammunition needed for the people who refuse to accept, believe, or even consider the fact that grains, fruits or vegetables may not be ideal for their beloved companions.
So, are Fruits and Vegetables Bad?
This is a tough question to answer, which is why it’s so hard for people to come to an accurate conclusion. Fruits and vegetables are not inherently bad and don’t cause your dog great harm. Fruits and veggies are not poisons. If your dog consumes them, you won’t see any immediate, negative reaction. The problem lies in that it is the wrong kind of food for them to eat. Why bother feeding fruits and vegetables if your dog cannot properly assimilate the nutrients from them? Since dogs weren’t designed to survive on carbohydrates, it’s really a moot point in my opinion.
It’s also worth mentioning because dogs lack the salivary enzymes to digest plant matter, consuming fruits and veggies places an additional burden on the pancreas tasking it with producing extra enzymes to deal with the starch, cellulose and carbohydrates. Feeding these foods strain the pancreas, making it work harder to produce more enzymes than normally needed to digest proteins and fats.
A great way to make sense of the exclusion of fruits and vegetables is to examine the following example. If you’re feeding your dog 50% meat and 50% carbohydrates (and we know he or she can realistically only digest and make full use of the nutrients from the meat, meaning 50% of the food fed) then you’re dog is only receiving 50% of the nutrients he or she needs. So although, fruits and veggies aren’t bad and are fine as a snack here and there, they really shouldn’t make up a regular portion of your dog’s diet.
Keep in mind, fruits and veggies don’t need to be shunned or feared. Pet owners just need to realize that although they’re a super food for us, they’re not nearly as beneficial for our dogs.
Makes Sense and Seems Simple Enough – So What’s the problem?
None of this information is new or extremely groundbreaking. The problem is that people have a hard time accepting this for several reasons.
Despite the fact that dogs are carnivores naturally, the majority of the population has been feeding dogs as omnivores for quite some time. Dogs have been fed grains, fruits and vegetables commercially for over 100 years- as long as pet food has been on the market. The pet food industry and veterinarians still recommend carbs and include carbs in pet food. Most people have a hard time believing that these authority figures are incorrect or worse – misleading them.
In addition, the belief that fruits and vegetables are a necessity is so deeply rooted within us all that many people refuse to accept that these foods don’t belong in their dog’s diet. Since we were children, we’ve been bombarded by messages telling us to eat our fruits and veggies for optimal health. Every single one of us is aware of the food pyramid and it’s recommendations on fruits and vegetables. The government, the education system, the media, and our families have been telling us we need to eat these nutrient dense foods for our whole lives! It’s safe to say it’s pretty engrained in our minds.
And because our society has the bad habit of treating our dogs like humans, we fail to realize that our dogs are vastly different from us not just in behavior but also in nutritional needs. Yes, fruits and vegetables are vital – but they’re vital for us! We are not true carnivores. Problems arise when we force our own beliefs and ideologies on our pets.
A perfect case study for this can be made in the recent headlines of a kitten that almost diet after it’s owners fed it a strict vegan diet. The interesting part of the story is that the kitten, which was extremely close to death, was revived not by antibiotics or western medicine. It was revived when veterinarians fed it nothing but meat! Let this be a valuable lesson – If a cat can be on the brink of death from eating ONLY fruits and vegetables, maybe this should demonstrate just how much our dogs and cats need carbs. Remember, it’s the meat in our pets diets that are providing valuable nutrients and keeping them alive.