The evidence behind the big questions in dog nutrition
How we grade the evidence
Not all studies carry the same weight. We grade each by design:
- Randomized trial. Dogs are assigned randomly to diets and compared. The strongest design for showing causation.
- Cohort or cross-sectional study. Dogs are observed, not assigned, so the studies can show a link but not a cause.
- Case series or survey. A set of real cases or reports, with no comparison group.
- Case report or opinion. A single account or an expert's view.
We also tag who funded each study. Funding does not make a finding wrong, but it tells you whose interpretation to scrutinize.
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Do grain-free diets cause dilated cardiomyopathy (DCM)?
In 2018 the FDA flagged a possible link between grain-free diets and dilated cardiomyopathy (DCM), a serious heart condition.
19 studies
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Is raw dog food safe?
Raw diets carry documented infection and nutrition risks, and the claimed benefits are mostly unproven.
19 studies
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Is fresh dog food worth it?
Fresh food has real, proven upsides and a steep price premium, but the “healthier and longer-lived” claims aren’t yet supported.
8 studies
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Does keeping your dog lean help them live longer?
This is one of the most settled findings in dog nutrition: leaner dogs live longer and healthier.
9 studies
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Does meeting WSAVA criteria mean a healthier dog?
It’s the best risk-reducing indicator an owner has, but it isn’t a certification, and no study shows it makes dogs live longer.
8 studies