Food & Nutrition
Homemade Pet Diets: The Nutrient Gaps That Show Up Without a Formulator
Updated July 30, 2026
By Morgan Reyes
The Short Answer
Four of two hundred. That's how many homemade dog food recipes, in the most detailed study ever run on this exact question, were written by a board-certified veterinary nutritionist. All four passed. The other 196 didn't.
That single comparison, from a 2013 UC Davis study, is a sharper answer than "homemade diets are often deficient," which is true but doesn't tell you what actually fixes it. Professional formulation wasn't correlated with success in that dataset. In the recipes tested, it was the entire difference between a nutritionally complete diet and one with a real gap in it.
| UC Davis (2013) | Dog Aging Project (2025) | |
|---|---|---|
| What was tested | 200 published recipes | 1,726 owner-fed diets |
| Missing at least one nutrient | 95% | 94% |
| Multiple deficiencies / fully complete | 83%+ had multiple | 6% fully complete |
| Professionally formulated | 4 of 200; all 4 passed | Not isolated as a variable |
Two studies, a decade apart, the same conclusion
The UC Davis study (2013). Jennifer Larsen, Jonathan Stockman, Andrea Fascetti, and Philip Kass, published in the Journal of the American Veterinary Medical Association, examined 200 homemade dog food recipes pulled from 34 different sources: veterinary textbooks, pet care books, and websites. They ran the actual ingredients and instructions through nutrient-analysis software rather than just reading the recipe for red flags.
The result: 95% of the 200 recipes lacked adequate levels of at least one essential nutrient, and more than 83% had multiple deficiencies. Only 4 recipes in the whole set were written by a board-certified veterinary nutritionist. All 4 had acceptable nutrient profiles. The other 196 recipes, regardless of how credible the source looked (a published book, a veterinary textbook), did not share that record.
The Dog Aging Project study (2025). Led by Janice O'Brien at the Virginia-Maryland College of Veterinary Medicine, with Texas A&M, and published in the American Journal of Veterinary Research, this one worked from the other direction: 1,726 homemade diets, described by the dog owners actually feeding them, assessed for nutritional completeness based on the ingredients and preparation methods reported. 94% were missing at least one essential nutrient, and only 6% were fully complete. Calcium and phosphorus imbalance was named as a specific, recurring concern, severe enough in some diets to risk a condition researchers called "rubber jaw," where bone softens from the mineral imbalance.
Different sample, different decade, different research group, same headline finding. UC Davis tested published recipes for what they'd deliver on paper. Dog Aging Project surveyed what real owners were actually feeding, in practice. Both land on the same conclusion: an unsupervised homemade diet is more likely than not to be missing something.
What actually goes wrong, and why it matters
The specific nutrients named as commonly deficient in the UC Davis study were choline, vitamin D, zinc, and vitamin E, and each carries a real, specific consequence rather than a vague "it's bad for them."
Choline and vitamin E deficiencies were linked to fat accumulation in the liver. Zinc and vitamin D deficiencies were connected to musculoskeletal abnormalities. Broader nutrient gaps generally were tied to immune dysfunction. None of these show up immediately. A dog can look and act completely normal on a deficient diet for a long stretch before a deficiency becomes clinically obvious, which is exactly why "my dog seems fine" isn't the same claim as "this diet is nutritionally complete."
This isn't an argument that homemade food is inherently worse than commercial food. It's an argument that formulating a genuinely complete diet is a harder problem than most recipe sources make it look, and that the credibility of where a recipe comes from (a published cookbook, a trusted-sounding website) doesn't track with whether it's actually complete.
If you're doing this anyway: what a formulator actually adds
A board-certified veterinary nutritionist isn't reading a recipe for obvious mistakes. They're calculating it against the same nutrient-profile targets AAFCO sets for commercial food, ingredient by ingredient, for the specific animal being fed.
That's the mechanical difference between the 4 recipes that passed and the 196 that didn't in the UC Davis dataset: a formulated recipe is built to hit specific nutrient minimums (the same kind of numbers this site's own label guides walk through for commercial food), not assembled from ingredients that sound nutritious and hoped to add up.
If home-cooking is the goal, a recipe from a board-certified veterinary nutritionist, individually formulated for your specific animal rather than a generic published recipe, is the version of this that the evidence above actually supports. A generic recipe from a book or a website, however well-reviewed, sits in the same untested category as 196 of the 200 recipes UC Davis examined.
Ninety-five percent of published recipes failed on at least one nutrient. The one variable that separated the recipes that passed from the ones that didn't wasn't the source's reputation, it was whether a board-certified veterinary nutritionist actually calculated the numbers. If you're going to cook for your pet, that's the one thing worth spending money on before anything else.
Bottom line: two separately-run studies, eight years apart, using different methods (one testing published recipes, one surveying what owners actually feed), both found the large majority of homemade dog diets missing at least one essential nutrient. The one factor that changed the outcome in the more detailed study wasn't the recipe's source or reputation. It was whether a board-certified veterinary nutritionist actually formulated it.
FAQ
Are homemade dog food recipes usually nutritionally complete?
No. 95% of the 200 recipes UC Davis examined in 2013 lacked at least one essential nutrient; a 2025 Dog Aging Project study found 94% of 1,726 owner-fed homemade diets had the same problem.
Does using a recipe from a veterinary nutritionist actually make a difference?
In the UC Davis dataset, it was the entire difference: all 4 professionally-formulated recipes passed, and the other 196 didn't. See the full comparison above.
What nutrients are most often missing from homemade dog food?
Choline, vitamin D, zinc, and vitamin E, per UC Davis's study, with consequences ranging from fatty liver accumulation to musculoskeletal abnormalities and immune dysfunction depending on which nutrient and how severe the gap.
Keep reading
- What Actually Counts as a "By-Product" in Pet Food. The commercial-ingredient side of the same question, for a reader weighing homemade against a commercial bag.
A guide on switching between foods without triggering gut upset, useful if you decide against homemade, is planned and not yet built.
A Note on Scope
This guide summarizes published research on homemade-diet nutritional completeness. It is not veterinary advice and does not evaluate any specific recipe. A homemade diet plan for an individual animal, especially one with a health condition, is a conversation with your vet or a board-certified veterinary nutritionist.
Sources
Image credits
- “Dog eating fresh meat in a bowl,” Ayla Verschueren / Unsplash, Unsplash License
- Larsen, Stockman, Fascetti & Kass, "Evaluation of recipes for home-prepared diets for dogs and cats," Journal of the American Veterinary Medical Association, 2013. Fetched 30 July 2026 via UC Davis's own news release. Source for the 95%/83% figures, the 4-of-200 professional-formulation comparison, and the named deficient nutrients and consequences.
- Texas A&M, "Most homemade dog diets lack nutrients, Texas A&M study finds", covering the Dog Aging Project study published in the American Journal of Veterinary Research, 2025. Fetched 30 July 2026. Source for the 94%/6% figures, the 1,726-diet sample, the calcium/phosphorus finding, and the "rubber jaw" detail.