This is the long-form evidence review behind our format choice. For the shorter version, see Why we chose raw.
Raw versus cooked dog food tends to produce stronger opinions than the evidence warrants. At one end, raw is sometimes presented as obviously superior simply because it is raw. At the other, the absence of a long-term randomised trial is used to suggest there is no meaningful evidence in its favour. Neither position represents the research particularly well.
There is no lifetime randomised trial showing which type of food produces the healthiest dogs. That is true of raw food. It is also true of lightly cooked food and kibble.
So the useful question is what the evidence we do have actually shows.
We have controlled feeding studies comparing raw, lightly cooked food and kibble. We have research looking at digestion, metabolism and the gut microbiome. And we have studies looking at diet and health over much longer periods.
No single study settles the question. Taken together, though, they have a direction.
What heat does to food
Heat changes food. That sounds obvious, but the detail matters.
Heating changes protein structure. Lower-temperature cooking can sometimes make proteins easier to digest by unfolding them. More intense heating can have the opposite effect, reducing digestibility through aggregation, oxidation and other structural changes.
So this is not a simple equation where every degree of heat makes food progressively worse. Temperature, duration, ingredients and processing method all matter.
Cooking also has another job. It reduces microbial risk.
That is why lightly cooked dog food is cooked in the first place. Heat provides an effective microbial-control step before the food reaches the customer.
Raw makes a different trade. It avoids the cooking step, and therefore the changes that step produces. But the microbial risk that cooking helps control has to be managed another way.
Those two effects, what heat does to the food and what it does for safety, are the real basis of the raw-versus-cooked comparison.
What the controlled studies in dogs show
Some of the most useful direct comparisons come from researchers at the University of Illinois. They are small studies. They also compare different commercial foods rather than one identical recipe served raw and then cooked.
Those limitations matter.
The results still tell us something.
The 2018 study
A 2018 controlled feeding study used eight adult dogs in a crossover design. The dogs were fed four commercial diets: one kibble, two mildly cooked refrigerated foods and one raw food.
The mildly cooked and raw diets were highly digestible. Compared with kibble, they produced greater nutrient digestibility overall, lower blood triglyceride concentrations and substantial differences in the dogs' gut microbial populations. The differences between raw and mildly cooked food were much smaller than the difference between those formats and kibble.
So this study does not give us a simple raw-beats-cooked result. It does show that kibble and the less-processed foods behaved differently once the dogs ate them.
The 2024 study
The newer comparison is more informative for the raw-versus-lightly-cooked question. Ten healthy adult beagles were fed five different foods: one kibble, one fresh mildly cooked food, one frozen raw food and two freeze-dried raw foods.
Kibble had the lowest digestibility values overall. The raw formats generally had the highest. More importantly, the fresh cooked food was significantly lower than raw formats on several measures.
Protein digestibility was lower in the fresh diet than in the frozen raw and both freeze-dried raw diets. Energy digestibility was also lower than in two of the raw formats. Other measures were more mixed.
So the result is not that raw won every measure. It is that where meaningful differences appeared between the fresh cooked and raw foods, they tended to favour raw.
That is a narrower claim. It is also an important one.
A related 2023 study using established rooster assays found a similar pattern. Most individual amino acids were highly digestible across the foods, but frozen raw provided more usable energy than the fresh cooked and kibble diets. It is supporting evidence rather than a dog-feeding trial. But again, it points in the same direction.
The evidence goes beyond digestibility
Digestibility is useful. It is not the only thing researchers have measured.
A 2021 Oklahoma State study compared 55 healthy dogs that had eaten either raw meat-based diets or kibble for more than a year. A veterinarian who did not know which diet each dog ate assessed their teeth, ears and skin. The raw-fed dogs had a modestly better combined clinical score.
There were differences between the groups too. Raw-fed dogs were more likely to receive dietary supplements and take part in sporting activities, so food cannot be separated cleanly from everything else that differed between them. The research was also funded by the American Holistic Veterinary Medical Foundation.
Those things affect how confidently we can interpret the result. They do not change what was measured.
The clinical score favoured the raw-fed dogs.
A 2025 study found metabolic differences too. Forty-six Staffordshire Bull Terriers ate either kibble or a raw meat-based diet for a median of around four and a half months.
Dogs eating kibble showed increases in measures including long-term blood sugar, blood lipids and bodyweight. Dogs eating the raw diet showed reductions in blood sugar, blood lipids and glucagon.
The foods differed in nutrient composition as well as processing. The study involved one breed, and body composition was not measured, so a change in bodyweight cannot be assumed to mean a change in body fat.
But the comparison still matters. The two diets produced different metabolic responses. On several of the measures researchers were interested in, those differences favoured raw.
What the longer-term research adds
Short controlled studies can tell us a lot about what happens over days or months. They cannot easily tell us what happens over years.
That is where observational research becomes useful. Some of the most interesting work comes from the University of Helsinki's DogRisk research programme.
A 2021 study analysed data from 4,022 dogs and looked at what they had eaten as puppies and whether their owners later reported allergy or atopy-related skin signs. The pattern was broader than raw food alone.
Raw tripe and raw organ meat were associated with lower later incidence, but so were human meal leftovers and fish oil supplements. Greater reliance on dry food sat on the higher-risk side of the analysis, alongside some other foods. Dogs eating more than 20% of their diet as raw food during puppyhood also had lower reported incidence.
This was based on owners recalling earlier feeding rather than researchers following puppies prospectively from the start. The interpretation has also been challenged in the same journal, with critics arguing that residual bias in the data and analysis could explain the associations. The DogRisk authors disputed that interpretation.
So this is not evidence that raw food has been shown to prevent allergies. It is evidence of an association. And the overall pattern favoured greater exposure to raw and other less-commercial feeding choices over diets dominated by dry food.
A 2023 DogRisk study found a similar direction for chronic enteropathy. Dogs eating more non-processed meat-based food during puppyhood and adolescence had a lower reported incidence later in life. Diets dominated by kibble were associated with higher incidence. Individual foods including raw bones and cartilage also appeared on the lower-risk side of the analysis.
The two observational studies draw from the same wider DogRisk data source, so they are different analyses rather than completely separate populations. But they ask different health questions. And both point in a similar direction.
The metabolic intervention described above also came from the DogRisk research group, but used a separate cohort and a different study design.
There is also a much larger 2025 Dog Aging Project analysis. It looked at owner-reported health conditions in 27,478 dogs and did not find a broad pattern of lower reported disease among dogs currently eating raw.
But it was a cross-sectional snapshot. Diet and health were recorded at roughly the same time, so it cannot tell us whether the food came before the condition, or whether a health problem influenced what the owner chose to feed. The authors describe the findings as most useful for generating and testing hypotheses.
The studies do not isolate heat perfectly
There is an important problem with almost every comparison above. The diets are different foods.
The frozen raw food in the 2024 study was not simply the fresh cooked recipe before it entered an oven. Raw food and kibble usually differ in ingredients, protein, fat, carbohydrate, moisture, fibre and processing. Raw and lightly cooked foods can differ in formulation too.
That means it would be wrong to say heat caused every difference researchers observed. It may have contributed. Other differences may have contributed too.
But this does not make the comparisons meaningless. Dogs do not eat isolated variables. They eat foods. And when different types of food repeatedly produce different outcomes, that is useful evidence when deciding which type of food to feed.
So does the evidence favour raw over lightly cooked?
This is where the distinction needs to be precise. The evidence for raw and less-processed food over kibble is stronger than the evidence for raw over lightly cooked food. But the second body of evidence is not absent.
The 2018 controlled study showed raw and mildly cooked foods both performing strongly relative to kibble, without a simple ordering between them. The newer 2024 study separated them more clearly. Across several digestibility measures, raw formats sat above the fresh cooked food. The supporting 2023 work produced some raw-over-fresh differences too.
Food science gives us a reason why that distinction might matter. Heating changes food, even when the cooking is relatively gentle.
The direct raw-versus-lightly-cooked evidence reviewed here comes from the controlled digestibility studies. Where they separate the two, the direction favours raw.
The wider health research asks a different question. It compares raw or less-processed feeding mainly with kibble or diets dominated by dry food. That supports the broader case for less-processed feeding. It does not settle the choice between raw and lightly cooked, and we do not use it as though it does.
Taken together, we do not think the evidence supports treating the choice between raw and lightly cooked food as nutritionally neutral. Where the controlled evidence distinguishes between them, the direction tends to favour raw.
How large that advantage is is less clear. But that is different from saying there is no evidence of an advantage.
We think raw is the better format. Not because lightly cooked food is inadequate. Not because one study has settled canine nutrition. Because avoiding heat has a clear food-science rationale, and the direct comparisons tend to favour raw where the two formats separate.
What has not been studied
No long-term randomised controlled trial has established which feeding format produces the best lifetime health outcomes in dogs. That means we cannot put a reliable number on any lifetime advantage, or say that raw has been shown to prevent a particular disease or extend lifespan.
The same limit applies to lightly cooked food and kibble. The comparison has not been done.
It limits how certain we can be.
It does not erase the evidence that exists.
And it does not make that evidence neutral.
Why cooking is used
There is a straightforward reason to cook dog food.
Safety.
Cooking is an effective way to reduce harmful bacteria. That matters particularly with meat.
A lightly cooked food therefore solves a real problem with a well-established method. We do not need to minimise that to make the case for raw. The question is whether cooking is the only responsible way to manage microbial risk.
It is not.
Raw food simply requires that work to happen elsewhere through ingredient controls, manufacturing hygiene, temperature control, testing and decisions about whether a batch is released. That creates additional responsibility. It does not remove it.
And it means the nutritional case for raw cannot be separated from the way a raw food is actually made.
What choosing raw requires
Choosing raw removes a control step. If a producer decides not to use cooking to control microbes, there should be something concrete in its place.
Ask what is tested. Ask when it is tested. Ask what happens if a batch fails. And ask whether you can see the result.
Those questions apply to any raw food, including ours.
The reasoning behind our own format decision is set out on Why we chose raw. What we do about the safety work that decision creates is set out separately.