Many dog owners add veggies, fruits, grains, and even nuts to their dogs meals, and while these additions generally do have nutritional benefits, to what degree they’re necessary will largely depend on your individual dog.
There are many reasons to consider adding food sources other than meat to your dogs diet, including the treatment of renal, pancreatic and hepatic issues. It’s also important to note that wild wolves often eat parts of an animal that are not sold in conventional grocery stores (like certain organs, glands, animal hides and feathers) so even if you’re trying to adhere to a strictly “prey-model raw diet”, there may still be nutritional deficiencies involved with feeding only meat purchased at a grocery store— which is where vegetables, fruits and other plant-based food sources start to come into play.
In addition to making up for any “nutritional gaps” that may exist in your dogs primarily meat-based diet, access to plant-based food sources also gives your dogs body the opportunity to absorb important anti-oxidant, mineral, and vitamin substances which may only come from plants — like Quercetin and Vitamin C.
If all of this sounds complicated, the good news is there is no evidence that offering your dog a moderate variety of plant-based foods has any long-term negative effects on their health. So, if you’d like to occasionally add steamed veggies to your dogs meal, or give your dog a few unsalted almonds as a snack, it most likely isn’t a problem. Nutrition is complex, and there is emerging research that suggests modern dogs are now more closely related to one another than to their wild ancestors — so the impact that evolving alongside, and being selectively bred, by humans for thousands of years cannot be understated when trying to achieve a balanced diet for your dog.
“Balance” can be somewhat of a misnomer, because it looks different for every dog, but the basic idea is this: there are certain things your dogs body can create (synthesize) on it’s own, and other things that it can’t. The nutrients that your dog cannot create are called “Essential Nutrients” because they must be obtained from food in order for your dog to survive. By this simplified explanation, a “balanced diet” is simply any diet that meets or exceeds your dogs minimum nutritional requirements, and can come in the form of diets based completely on meat, or diets that include plant matter.
Dogs have 6 Essential Nutrients: water, fat, carbohydrates, protein, minerals, and vitamins, all of which are necessary to support your dogs vital organs and immune system. Essential nutrients can be obtained from both meat and plant-based sources, and although we can tell dogs evolved primarily to eat meat by their physiology (sharp teeth, short intestinal tracts) a growing body of evidence supports that even wild wolves supplement their own diets with fruits and vegetables seasonally, and that many vegetables have properties that help reduce inflammation, and, in controlled studies, significantly decrease risk of developing certain cancers.
With all that being said, what “balance” looks like is different for every dog. For example, while some dogs do well on a high-fat diet, those predisposed to pancreatic issues will struggle to cope with the excess fat, and may be better suited to a diet with a higher percentage of lean protein. Similarly, while some dogs enjoy cooked carrots or peas being added to their diet, others do not tolerate starch well and can easily get sick, or gain weight.
Truly evaluating whether or not your dogs diet is balanced to meet their nutritional needs requires blood-work from a veterinarian, which can show if your dog is lacking in certain minerals and vitamins, as well as give you a clearer picture of how their diet is affecting their overall health. Short of that, most dog owners judge the quality of their dogs diet by their dogs overall appearance, look and feel of their dog’s coat, energy levels, stool size/appearance, and body weight.
While a small amount of plant matter in a dogs diet is OK, it is not as easily digestible for them as it is for humans and needs processing (pulverizing, boiling, dehydrating, etc) before being fed. This is in part because breaking down the starches found in plants requires the production of a chemical called “Amalyse,” which humans and many other omnivorous animals secrete through their saliva, digesting food the instant it hits our tongues. But for dogs, this chemical is only created by the pancreas, so the addition of excess vegetables to a dogs diet can be incredibly taxing on this sensitive organ.
The over-abundance of carbohydrates in commercial dog food (typically more than 60%, to remain shelf-stable) is what makes many dog owners look at raw diets in the first place. And while some dog owners that feed raw remain staunchly against adding plant-matter of any kind, those that do typically include fruits, veggies, or other plant-bassed supplements at a maximum of 2-3x per week. Outside of dogs with special medical conditions, the general consensus is that plant-matter should also not exceed 20% of any one meal, to ensure that any new additions do not make your dog sick.
Every dog is different, and although dogs do have very adaptive digestive systems (there are completely vegetarian & vegan dog foods out there) getting adequate nutrition from non-meat sources, like legumes, soy, and lentils, is much more difficult on your dog's body. Except in the case of severe meat allergies, most dogs do best on a diet consisting primarily of fresh raw meat, with fruits, vegetables, and other non-meat supplements added only a few days a week.