What the FDA Grain-Free and DCM Investigation Actually Shows: A Guide

The FDA investigation into grain-free diets and canine dilated cardiomyopathy (DCM) is one of the most cited, and most misread, episodes in modern pet food. It is routinely summarised either as proof that grain-free is harmful or as proof that the diets were cleared, and neither summary is accurate. This guide reconstructs the dossier from the official record: when it opened, what it counted, which brands it named, why it paused, and where it formally stands in 2026. The sources are the FDA's own updates (FDA, 2019; FDA, 2022) and the reporting of the veterinary profession (AVMA, 2022). The goal is to let a reader see the inquiry for what it is, a careful regulatory observation that never reached a causal conclusion.

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General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.

On this page (What Grain)

• What was the FDA investigation, and when did it start?
• Where does the investigation stand now?
• Is the investigation closed, or still open?
• How many cases were reported, and which brands were named?
• Why did the FDA stop emphasising brands?
• Have European authorities taken a position?
• The bottom line

What was the FDA investigation, and when did it start? {#timeline}

The FDA opened its public alert in July 2018, after veterinary cardiologists reported dilated cardiomyopathy in dogs eating atypical diets. Three status reports followed across 2018 and 2019, with the most detailed analysis published in June 2019. The agency's Center for Veterinary Medicine ran the inquiry through its adverse-event reporting system, the same pharmacovigilance machinery it uses across animal foods and drugs.

The investigation was observational from the outset. It gathered voluntary reports submitted by owners and veterinarians, then looked for patterns in the diets involved. This design is good at spotting a possible signal but poor at proving a cause, because the reports vary in quality and lack a controlled comparison group. Understanding that built-in limitation is the key to reading everything that followed.

By the time the agency consolidated its data, it had recorded 1,382 canine reports of the disease between 1 January 2014 and 1 November 2022 (FDA, 2022), a span of nearly nine years. The timeline below shows the main stages.

Where does the investigation stand now? {#status}

The investigation is dormant but not closed. On 23 December 2022 the FDA announced it would issue no further public updates unless substantial new scientific information warranted them (AVMA, 2022). The agency explained that voluntary reports, lacking full diagnosis or verified diet history, could not establish a causal product link, so there was nothing new to report.

This is a frequently misread point. The December 2022 announcement marks a communication pause, not a scientific conclusion and not a clearance of the diets involved. The dossier remains formally open in 2026, and the agency said it would resume communication if a notable finding emerged. The pharmacovigilance system also stays active, so adverse-event reports continue to be received and can be mined by researchers.

In the absence of fresh regulatory output, academic research took over. The Tufts Cummings School became a focal point, and roughly fifteen peer-reviewed studies appeared between 2019 and 2025 exploring the mechanism. None delivered proof of direct causation, and the picture they paint is of a complex, still-unresolved question rather than a settled one.

It is worth being clear about what a regulator can and cannot do with data of this kind. The FDA's adverse-event system is a surveillance tool, designed to catch early warning signals across the whole market, not a controlled experiment. A signal it raises is a hypothesis to be tested, not a finding to be acted on, and the agency has no power to manufacture the randomised, controlled evidence that would settle causation; that work falls to universities and independent researchers. Seen in this light, the December 2022 pause is less a retreat than an honest acknowledgement that the surveillance tool had reached the limit of what it could establish, and that the next step belonged to a different kind of study.

Is the investigation closed, or still open? {#open-or-closed}

Still open, simply without active communication. Closing an investigation and ceasing to comment on it are two different regulatory acts, and the FDA chose the second: it keeps the file open while publishing no fresh counts (AVMA, 2022). No official FDA document declares grain-free diets exonerated, contrary to what some summaries imply.

What this means in practice is that the absence of updates signals neither confirmed danger nor proven safety. It reflects the impossibility, with voluntary reports alone, of settling causation in either direction. The honest reading of the silence is that the question was parked for want of decisive data, not answered.

Progress since 2022 has therefore come from independent publications, and they illustrate the lingering disagreement. One 2023 study reported improved survival in 91 pit bull-type dogs after a switch to a traditional diet (JAVMA, 2023), evidence consistent with a dietary role; other work found no cardiac change in dogs fed high pulse levels. A 2025 narrative review still calls the phenomenon multifactorial and unresolved (narrative review, 2025).

How many cases were reported, and which brands were named? {#cases-brands}

The FDA received 1,382 reports of dilated cardiomyopathy in dogs between 2014 and November 2022 (FDA, 2022). At an interim point it had logged 524 reports up to April 2019, of which 515 were dogs and 9 cats. Most submissions arrived after the 2018 alert, a sign of the notification effect that follows any public health announcement.

In June 2019 the agency published the list of brands appearing in ten reports or more. Acana (67 cases), Zignature (64) and Taste of the Wild (53) led the frequencies, and 16 brands in all crossed the ten-case threshold (FDA, 2019). The FDA stressed that the list reflected reports, not proof of harm, and named no responsible product. These reports are voluntary and establish no demonstrated responsibility.

Why did the FDA stop emphasising brands? {#brands-caution}

Because a report count depends heavily on how many bags a brand sells. A top-selling brand mechanically generates more submissions than a niche one, regardless of any real difference in risk, and media exposure amplifies the effect further. Read without that context, the brand list invites a comparison it cannot support.

The agency recognised this and dropped its emphasis on brands in later communications, judging report counts too dependent on market share to ground a fair comparison. It refocused the analysis on ingredients, particularly pulses, which proved a more informative common denominator than any brand name. This shift is itself a useful lesson in how to read the data: the frequencies say more about exposure and reporting behaviour than about product safety.

For an owner, the takeaway is that the 2019 brand list should not be treated as a ranking of dangerous foods. It was a snapshot of where voluntary reports clustered at one moment, and the FDA itself moved away from framing it as anything more.

The ingredient-centred reframing also proved more scientifically productive. Once the analysis shifted from brand names to composition, a clearer common denominator appeared: not the grain-free label but the prominence of pulses, with 93 percent of reported diets containing peas or lentils (FDA, 2019). That finding redirected research toward plausible biological questions, such as whether pulses affect taurine metabolism or protein digestibility, rather than toward a list of company names that reflected sales as much as anything. The lesson for reading any pharmacovigilance dataset is the same: frequencies follow exposure, and the useful signal usually lies in what the affected cases share, not in who sold the most product.

Have European authorities taken a position? {#europe}

No European authority has published a dedicated formal position. The investigation was an American one, run by the FDA from 2018 onward, and no European agency opened an equivalent inquiry or issued an alert. Neither EFSA nor FEDIAF has put out a specific warning, and the subject sits mainly in the scientific literature on the European side.

EU feed law, including Regulation (EC) 767/2009 on labelling, frames which claims are permitted but does not address the cardiomyopathy and grain-free question (EUR-Lex). FEDIAF, the European pet food industry federation, issues nutritional recommendations based on the National Research Council, with no criterion for or against grain-free and no cardiac warning tied to pulses. European academic work has generally aligned with the FDA's caution: a possible association, causation not demonstrated.

This absence of an institutional European position is worth flagging, because some sources imply a regulatory consensus that does not exist. For an individual case anywhere in Europe, a veterinarian or board-certified veterinary nutritionist remains the reference contact, for want of an official doctrine.

The bottom line {#recommendation} (What Grain)

The FDA investigation is best understood as an open, paused, observational inquiry that found a consistent signal but never proved a cause. It documented 1,382 canine reports, named 16 brands in 2019 while warning against reading harm into the list, and then stopped public updates in December 2022 for lack of decisive new data, without closing the file or clearing the diets. The most accurate way to use this record is to treat it as a reason for informed attention to a formula's pulse content and documentation, not as either an indictment or an all-clear. Where a cardiac question is live for a specific animal, the dossier points the reader toward a veterinarian rather than a verdict.

Continue reading (What Grain)

• Where does the FDA investigation into grain-free diets and heart disease stand?
• Has the FDA closed its grain-free and DCM investigation, or is it still open?
• How many DCM cases were reported to the FDA, and which brands were named?
• Glossary: FDA CVM
• Glossary: DCM (dilated cardiomyopathy)
• Hub: Grain-free and DCM

Sources: FDA, Questions and Answers CVM Investigation (2019); FDA, Investigation update (December 2022); AVMA, FDA will end public updates (2022); Owens et al., JAVMA (2023); narrative review, Veterinary Sciences (2025); Regulation (EC) 767/2009 (EUR-Lex); FEDIAF, Nutritional Guidelines.