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Are popular dog foods and ingredients like corn healthy or just fillers?

Updated On September 23rd, 2025

Pet's info: Dog | Cavalier King Charles Spaniel | Female | spayed | 6 years and 3 months old | 17 lbs

Are grocery store foods and foods like purina and royal canin/science diet considered McDonald's for dogs? (Junk food) why or why not? Please explain. Also why are ingredients like corn, meat byproducts, wheat, soy, etc. considered healthy? These seem like filler ingredients to me. Aren't sweet potatoes, brown rice, peas and named meat meals healthier and more nutritious? What is the science behind corn and wheat etc. being nutritious or actually good and wholesome for dogs? Can someone explain?

2 Answers

Most Helpful Answer

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Answered By David Elbeze, DVM, MRCVS

Veterinarian

Published on October 9th, 2018

These brands you mentioned are considered at least in my mind to be mid range foods, it's no McDonald's but it's not super healthy either. same foes for all the ingredients you mentioned, these are indeed fillers, some more problematic than others (such as meat byproducts for example). Dogs are considered omnivores but are truly carnivores, meaning they need mainly meat/fish in their diet, but economically and realistically it's not doable, there are too many dogs/cats and not enough meat on earth to keep with the demand.

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    Answered By Jessica Desrosiers

    Veterinary Technician

    Published on October 10th, 2018

    That's a lot of questions! I'm not the person you originally asked this to, but perhaps I can help. Foods like Royal Canin and Science Diet are actually considered OK quality foods, and not really "junk food". Junk food type diets tend to be almost all filler, or have poor quality ingredients such as low grade protein sources, cellulose fillers, etc. Meat byproducts, corn, wheat, etc aren't considered low-quality fillers depending on how they are processed. Items like whole corn are going to be hard to digest, obviously, (think about when you eat corn on the cob versus say, a corn muffin, and the end result) but corn once ground down actually provides a great carbohydrate energy source as the insides of the kernel are very easily digestible. The same goes with other grains such as wheat. Meat byproducts still provide a great source of proteins, calcium, etc that provide nutrition provided they are broken down into more easily digestible components before being added into the food. Food items like peas, rice, sweet potato, etc, can definitely provide great nutrition as well, and may be easier to digest if your pet has an underlying condition that either causes an allergy to ingredients such as wheat or corn, or other underlying health issue where protein/vitamin levels, etc may need to be altered to treat the issue. These can also be good alternative sources for pets with sensitive stomachs or skin issues, again due to allergies to other ingredients. The end case boils down to your pet's individual needs, if they have any healthy issues, and if they have any food allergies. If you find your dog does just great on Science Diet, then sticking with that diet is perfectly fine. If you feel they do better on something with rice or sweet potato, then offering those foods instead works out well too.

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