Yes. For most dogs, eating nothing but kibble their whole life is likely doing them harm. Not always dramatically, and not overnight. But over years of daily exposure to ultra-processed food, the evidence is mounting, and in fact we are seeing this in practice that it contributes to chronic inflammation, gut dysfunction, dental disease, obesity, metabolic diseases and cancer.
I say this as a vet who spent years recommending it.
This is the first in a series of posts on pet nutrition. My goal is to share what I have learned honestly, so you can make better decisions for your dog. We’ll look at what kibble actually is, what it does inside your dog’s body, and what you can realistically do about it.
Why did vets start recommending kibble in the first place?
When I graduated from vet school, kibble was simply what we told everyone to feed. Our nutrition lecturers were sponsored by a major pet food brand. As students, we received free or heavily discounted pet food from them. It was practical, convenient, shelf-stable, and presented to us as nutritionally complete and balanced.
What we weren’t taught much about were the long-term effects of feeding a single, ultra-processed food for an animal’s entire life. The stories we did hear were mostly warnings about raw food, never about the bag on the shelf.
In 1976, Colgate-Palmolive acquired Hills Pet Foods and applied the same marketing strategy they had used for toothpaste: get dentists to recommend it, and consumers follow. Sponsoring vet school nutrition programmes, funding research at veterinary schools, and supplying free food to students proved enormously effective. Hills grew from a US$50 million company into the fourth largest pet food company in the world. That strategy shaped a generation of vets, including me.
How is kibble actually made?
More than 95% of dry dog and cat food is manufactured through a process called extrusion. Here’s what that means.
All ingredients, whether protein, carbohydrates, fats, vegetables, or vitamins, are first ground into a uniform powder called a “meal.” This meal is mixed with steam and water to form a dough, which is then pushed through a machine called an extruder. Inside the extruder, temperatures reach between 160 and 200 degrees Celsius under extreme pressure. The heat causes the starch molecules to burst open and absorb moisture, in a process called gelatinisation. That gelatinised starch is what holds the kibble together. When the dough is forced out of the extruder into normal air pressure, the water evaporates rapidly and the kibble puffs into its characteristic shape.
The kibble is then dried down to under 10% moisture.
Here’s the critical problem: that extreme heat destroys most of the vitamins, essential amino acids, and natural fats in the food. To compensate, manufacturers spray synthetic vitamins, fats, and artificial flavours back onto the outside of the finished product. What your dog eats is not the sum of its raw ingredients. It’s a processed product designed to resemble them.
And to form that solid structure at all, kibble requires between 30% and 60% carbohydrates as a binding agent. Even grain-free kibble contains carbs, in the form of potato, tapioca, chickpea, or lentils.
What does kibble do to your dog’s body?
Does kibble cause inflammation in dogs?
Yes, and the mechanism is straightforward. The high carbohydrate load in kibble, even premium brands, causes rapid spikes in blood glucose after every meal. Dogs and cats are not metabolically designed for this. Their digestive systems are built for protein and fat, not starch. Repeated insulin spikes, meal after meal, day after day, create a state of chronic low-grade inflammation throughout the body.
This inflammation is a known precursor to obesity, diabetes, kidney failure, and organ dysfunction. It’s also why many of the dogs we see in clinic are overweight despite owners feeding them what they believe is a healthy diet.
That high carbohydrate load also coats the teeth. Saliva converts those carbs into sugars, and those sugars accelerate plaque formation. We see severe dental disease in young dogs all the time. Many of them have been eating nothing but high-quality kibble their whole lives.
Can kibble increase a dog’s cancer risk?
The research on this is concerning. The high-heat manufacturing process triggers what is called the Maillard reaction, the same chemical process that browns bread or caramelises onions. In kibble, this reaction produces compounds called Advanced Glycation End-products (AGEs) and potential carcinogens including acrylamide and a chemical called 5-hydroxymethylfurfural (HMF).
In humans, AGEs are linked to chronic inflammation, diabetes, liver disease, kidney disease, obesity, cardiovascular disease, cognitive decline, and cancer. We’re seeing similar disease patterns emerge in our canine and feline patients.
What makes this particularly significant for pets is the cumulative dose. Because dogs eat the same processed food for every single meal of their lives, their exposure to these compounds far exceeds what any human would encounter. Research has found that dogs ingest 122 times more of the potential carcinogen HMF than humans, and cats ingest 38 times more.
What does kibble do to my dog’s gut health?
The diversity of bacteria in your dog’s gut directly influences their immune function and overall longevity. A dog fed exclusively on kibble has a significantly less diverse gut microbiome compared to a dog eating fresh or minimally processed food.
Without the variety of beneficial bacteria and the natural fibres found in whole foods, the gut lining can become what we call hyper-permeable, or “leaky.” Over time, this impairs immune function and digestive tolerance. These are the dogs who vomit regularly, eat grass on every walk, or produce loose, mucousy stools. I know this pattern well. My own greyhounds were doing all of it when they were on kibble.
Are there chemicals in kibble I should be aware of?
Yes. Dry pet foods contain significantly higher concentrations of parabens, which are classified as endocrine-disrupting chemicals. A 2018 study found parabens and their metabolites in 100% of pet food and urine samples tested. For cats in particular, the majority of this chemical exposure was traced directly to their diet. The long-term clinical trials are not yet complete, but continuous daily exposure to known endocrine disruptors from a very young age carries real and unstudied risk.
Not reliably. Kibble relies on synthetic preservatives to stop the fats going rancid, but those preservatives don’t prevent vitamins from degrading over time. Once a bag is opened, especially if not stored correctly, the nutrient content starts to fall. Thiamine (Vitamin B1) is particularly vulnerable. Thiamine deficiency can cause neurological symptoms, though more commonly you’ll see GI upset first.
If you are feeding kibble, keeping the bag sealed, stored in a cool dry place, and used within six weeks of opening makes a genuine difference.
So do I need to stop feeding my dog kibble completely?
Not necessarily, and I want to be honest about this: kibble has its place. It is affordable, convenient, and far better than nothing. Some dogs tolerate it well. And the evidence doesn’t suggest a single meal of kibble is harmful. The concern is a lifetime of it as the only food source, every single meal, every single day.
What the research does show is that even partial substitution helps. Replacing just 20% of your dog’s daily kibble with fresh, minimally processed food has a measurable positive impact on health outcomes. That is genuinely achievable for most pet owners. You don’t need to cook every meal from scratch or switch overnight.
What I feed my own greyhounds now
I have three greyhounds. When they were on kibble, their coats were dull, they had dandruff, their stools were consistently loose with mucus, and they ate grass and vomited one to two times a month. On the best quality kibble I could source, I should add.
After reading The Forever Dog by Dr Karen Becker and Rodney Habib, and studying a course in small animal nutrition, I transitioned them to a combination of gently cooked and raw food. The difference has been noticeable. Their coats are healthier, their digestion has settled, they have lost weight, lived longer and are genuinely enthusiastic about eating their food.
In the next posts in this series, we’ll explore the practical alternatives to kibble and how to introduce them without stress.
In the meantime, if you have questions about your pet’s diet, come and have a chat with us at Lynbrook Vet or Berwick Clyde Vet. We’re very happy to talk through your options.
Frequently Asked Questions
Is kibble bad for dogs?
Kibble isn’t acutely toxic, but there is growing evidence that a lifetime of eating nothing but ultra-processed dry pet food contributes to chronic inflammation, gut dysfunction, dental disease, and metabolic disorders. Replacing even 20% of your dog’s kibble with fresh or minimally processed food has been shown to have a measurable positive effect on health.
Why do vets recommend kibble if it’s not ideal?
Most vets, including Dr Kunal, trained on nutrition curricula sponsored by major pet food companies. Kibble was presented as balanced, safe, and convenient, and the long-term downsides weren’t widely discussed. Veterinary nutrition education is evolving, and more vets are now looking at the research critically.
What’s the difference between grain-free kibble and regular kibble?
Grain-free kibble replaces grains like wheat and rice with carbohydrates from potatoes, tapioca, chickpeas, or lentils. It still requires 30%-60% carbohydrates to hold its shape. The starch source changes, but the fundamental issue of a high-carbohydrate, ultra-processed diet remains. Grain-free is not the same as low-carbohydrate.
How do I know if my dog’s diet is affecting their health?
Common signs include recurring loose or mucousy stools, frequent vomiting or grass-eating, a dull or flaky coat, dandruff, low energy, and persistent bad breath. These aren’t definitive proof of diet issues, but they’re worth discussing with your vet, particularly if they’ve been present long-term.
What should I feed my dog instead of kibble?
There is no single right answer, and the best option depends on your dog’s age, health, and your circumstances. Gently cooked whole food, raw feeding, and freeze-dried foods are all options worth exploring. Even adding 20% fresh food to an existing kibble diet makes a meaningful difference. Talk to your vet before making significant dietary changes, especially for dogs with existing health conditions.
Is raw food safe for dogs?
Raw food comes with real benefits, but also real risks if not handled correctly. Bacterial contamination, nutritional imbalance, and parasites are genuine concerns when raw feeding is done without guidance. We’ll cover this in detail in an upcoming post in this series. In the meantime, gently cooked food offers many of the benefits of raw with lower handling risk.
