The Question She Kept Asking Her Vet

Melissa Vandenberg had been feeding her two Labrador Retrievers, Scout and Archie, a premium grain-free kibble for six years before she started noticing things she couldn't explain. Scout had gained almost nine pounds since turning five despite the same portion sizes. Archie was lethargic in the afternoons in a way that didn't match his age or activity level. Both dogs had recurring ear issues that cleared up with medication and came back within weeks. Melissa, who works as a nurse practitioner in Portland, Oregon, spent enough time with metabolic panels in her professional life that the pattern bothered her.

"I kept asking the vet about diet," she said. "And I kept getting the answer that kibble was complete and balanced and that I shouldn't worry. I didn't feel like that was the whole story."

She wasn't wrong to wonder. A controlled study published in late 2025 by researchers at the University of Helsinki's DogRisk research group is the most precisely designed comparison of kibble and raw diet effects in dogs to date — and its findings have implications that extend well beyond the question of what to put in a dog bowl.

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What the Study Did

The DogRisk team at the University of Helsinki's Faculty of Veterinary Medicine, led by Dr. Sarah Holm, designed a crossover trial using 46 Staffordshire Bull Terriers — a single breed, to eliminate the confounding variable of genetic differences across populations. Each dog received both diets in sequence: a high-carbohydrate commercial kibble and a raw meat-based diet. Researchers measured a battery of metabolic biomarkers before and after each dietary period, including blood glucose, glycosylated hemoglobin, insulin, glucagon, cholesterol, triglycerides, and the triglyceride-glucose index — a marker of insulin resistance developed for human metabolic research and applied here to dogs for the first time.

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The results divided cleanly along dietary lines. Dogs on the kibble diet showed increased long-term blood sugar, blood lipids, and bodyweight. Dogs on the raw food diet showed decreased blood glucose, blood lipids, and glucagon levels. Both groups showed increased ketone bodies, but levels were significantly higher in the raw food group — indicating the raw-fed dogs were more reliant on fat for energy, a metabolic state researchers associated with greater metabolic flexibility.

Dr. Holm said: "Interestingly, the kibble diet was associated with changes often linked to adverse metabolic health, while the raw food diet promoted metabolic responses generally considered favorable. More research is needed to understand the long-term health implications of these two feeding strategies."

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The Insulin Resistance Connection

The triglyceride-glucose index finding is perhaps the most striking detail in the study, because of where that measurement comes from. The TGI score is a tool developed to assess insulin resistance in human patients — a precursor state to Type 2 diabetes, metabolic syndrome, and a range of cardiovascular complications. Its application to dogs is new. The fact that raw-fed dogs in the trial showed lower TGI scores — meaning less insulin resistance — while kibble-fed dogs showed higher ones is a finding that researchers are treating carefully, but not dismissing.

Dogs are not humans. Their carbohydrate metabolism differs in meaningful ways, and a 4.5-month controlled trial using one breed cannot establish long-term health outcomes across the broader canine population. The DogRisk researchers said explicitly that more research is needed before making broad recommendations.

What the study can say is more limited and more specific: under these conditions, in these 46 dogs, over this time period, a high-carbohydrate kibble produced a measurable set of metabolic changes that, in human medicine, would be considered markers of metabolic stress. A raw meat-based diet produced the opposite pattern. The question of what that means across years of feeding, across diverse breeds, and across dogs with different health conditions remains genuinely open.

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The Dental Data

The metabolic study is not the only recent finding complicating the simple story that kibble is nutritionally complete and equivalent to less-processed alternatives. A separate analysis of data from 4,771 Finnish dogs in the DogRisk dataset, also published in 2025, found that feeding non-processed meat-based diets — including raw bones and cartilage — during puppyhood and adolescence was significantly associated with lower risk of dental calculus, while high-carbohydrate kibble diets during the same developmental periods were associated with higher risk.

Dental disease is the most commonly diagnosed condition in adult dogs in the United States, affecting an estimated 80% of dogs over the age of three. If diet in early life influences the trajectory of dental health in a measurable way, it becomes relevant to how veterinarians advise clients during puppy appointments — not just to the debate between raw feeding advocates and conventional nutrition guidelines.

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The Other Side of the Conversation

Raw feeding is not without legitimate concerns, and the study does not pretend otherwise. Raw meat-based diets carry documented risks of bacterial contamination — including Salmonella and antimicrobial-resistant E. coli — that can affect dogs, their owners, and other people in the household. Multiple studies, including a 2024 analysis from the University of Liverpool, have found raw commercial dog foods frequently contaminated with bacteria that would not be present in cooked or processed alternatives. For immunocompromised dogs, elderly owners, or households with young children, these risks are not theoretical.

The DogRisk researchers have consistently acknowledged that raw feeding requires careful formulation, safe handling practices, and attention to mineral balance — a 2025 analysis in Scientific Reports found that many pre-made raw dog foods still do not meet established mineral guidelines. A nutritionally incomplete raw diet is not better than a complete kibble, regardless of what the metabolic markers show.

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What It Means for the Average Dog Owner

Melissa Vandenberg in Portland switched Scout and Archie to a gently cooked diet in January 2026 after consulting with a veterinary nutritionist. She did not go fully raw — the logistics of her household made it impractical, and she had concerns about handling safety. Scout has lost six of the nine pounds he had gained. Archie's afternoon lethargy has improved enough that she notices it.

"I'm not saying kibble is poison," she said. "I'm saying that for my specific dogs, something needed to change. And the research gave me the confidence to ask better questions."

That, more than any diet verdict, may be the most accurate summary of where the science currently stands. The era of assuming that ultra-processed, high-carbohydrate dog food is nutritionally equivalent to all alternatives is ending. What replaces it is not a simple answer. It is a more honest conversation between dog owners and their veterinarians — one that the data is making harder to avoid.