Grain-free and heart disease, by the numbers

Dilated cardiomyopathy, or DCM, is a disease in which the heart muscle weakens and the chambers enlarge, reducing the heart's ability to pump. Since 2018 it has been linked in public discussion to grain-free dog food, and the link is real enough to take seriously and weak enough to be widely misunderstood. The most useful way to cut through the noise is to look at the actual figures the FDA has published, because the numbers tell a more careful story than the headlines built on them. This article lays out that data and what it can and cannot support.

Petipedia · Editorial team

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

What the FDA actually counted

The investigation began with a signal, not a conclusion. Between 2014 and April 2019 the FDA logged 524 reports covering 515 dogs and 9 cats, more than 90 percent of them fed grain-free diets (FDA, 2019). Extending the window, between 1 January 2014 and 1 November 2022 the agency recorded 1,382 canine reports of the disease, a span of nearly nine years (FDA, 2022). Spread across a national dog population in the tens of millions, that is a very small number of reports, which is the first piece of context usually missing from the conversation.

The second piece is what the reported foods shared. The early signal was not really about the absence of grain. The shared denominator was pulses near the top of the ingredient list: 93 percent of the reported foods contained peas or lentils (FDA, 2019). The term that stuck, grain-free, may be a marker for a different feature, pulse-rich formulation, which is why researchers increasingly describe the phenomenon as diet-associated rather than grain-free DCM.

The taurine wrinkle

Early hypotheses centred on taurine, an amino acid essential for feline heart health and relevant in some dogs. The picture turned out to be more complicated. A 28-day 2023 study found no taurine drop on a pulse-based diet (PLoS ONE, 2023), which illustrates that the mechanism, if there is one, exceeds taurine alone. This matters because "just add taurine" was an early popular fix, and the data does not support treating it as a complete explanation.

Why there has been no recall

This is the figure that surprises people most. Despite years of investigation and more than a thousand reports, the FDA has issued no product recall on the basis of DCM, for want of proven causation (AVMA, 2022). To date no agency has banned grain-free food or issued a recall based on dilated cardiomyopathy (AVMA, 2022). Regulators act on demonstrated causation, and an association, however worth investigating, is not causation. The reports describe a correlation that researchers are still working to explain.

Open, paused, not closed

A common misconception is that the FDA closed the case, in either direction. It did neither. The agency never formally closed the investigation; it only suspended public updates in December 2022 for lack of new data, and said it would resume if the science advances (AVMA, 2022). The pharmacovigilance system still receives adverse-event reports that researchers can consult and mine (FDA, 2022). "Paused for lack of new data" is not the same as "resolved", and it is certainly not the same as "disproven".

Two 2023 studies that pull in different directions

The reason researchers will not call this settled is that recent evidence genuinely points both ways. Two 2023 studies illustrate the lingering disagreement. One reported improved survival in 91 pit bull-type dogs after a switch from a suspect diet to a traditional one (JAVMA, 2023), which is the strongest practical hint that diet can matter in affected animals. The other found no cardiac change in dogs fed high pulse levels (PLoS ONE, 2023), and as noted, a 28-day study found no taurine drop on a pulse-based diet (PLoS ONE, 2023). When one study shows dogs improving after a diet change and another shows healthy dogs unaffected by pulses, the honest summary is that the mechanism is real for some animals and absent for others, and nobody yet knows the rule that separates them. Lacking a quantified control group across the report base, the evidence stays at the association level, which the AVMA deems insufficient for a firm conclusion (AVMA, 2022).

Inherited DCM versus diet-associated DCM

A crucial distinction often lost in the noise is that DCM is not one disease with one cause. There is a long-recognised inherited form that runs in particular large and giant breeds, such as Dobermanns and Great Danes, and has nothing to do with food. The newer concern is a diet-associated form that appears in dogs outside those predisposed breeds, often fed pulse-rich diets, which is precisely the population the FDA examined among its more than 90 percent grain-free cases (FDA, 2019). This matters for two reasons. An at-risk-breed dog needs cardiac monitoring regardless of diet, and a dog of a non-predisposed breed developing DCM is the more striking signal, because there is no inherited explanation to fall back on. Conflating the two forms produces both false alarm and false reassurance.

What "paused, not closed" actually changes

The December 2022 pause is frequently misread as a verdict, so it is worth being precise about what changed and what did not. Closing an investigation and ceasing to comment on it are two different acts, and the FDA chose the second: it keeps the file open while publishing no fresh counts (AVMA, 2022). On 23 December 2022 the agency announced it would issue no further public updates unless substantial scientific information warranted it (AVMA, 2022). In practice that means three things. New adverse-event reports are still collected through the pharmacovigilance system and remain available to researchers (FDA, 2022). No regulator, neither the FDA, the AVMA nor FEDIAF, has banned these diets or advised halting them (AVMA, 2022). And the agency has explicitly left the door open to resume if the science advances. A paused investigation is an unfinished one, which is a poor foundation for a confident claim in either direction.

The data in one place

What this means for an owner

Three reasonable conclusions follow from the numbers, and none of them is alarmist. First, the reported risk is statistically small, but the topic is serious because DCM can be fatal, so it deserves attention rather than panic. Second, the relevant feature may be pulse-rich formulation rather than the mere absence of grain, which means swapping one pea-heavy grain-free recipe for another pea-heavy one is not obviously a solution. Third, because causation is unproven and the case is paused rather than closed, the prudent move is to discuss diet choice with a vet rather than to act on a slogan in either direction.

It also helps to know the baseline. Some breeds, such as certain large and giant breeds, carry a genetic predisposition to DCM that has nothing to do with diet, and the diet-associated form appears in dogs outside those breeds, often fed pulse-rich diets, which is the population the FDA examined (FDA, 2019). Separating inherited risk from diet-associated risk is part of any sensible conversation with a vet.

A few practical signals are worth knowing without becoming a source of anxiety. DCM can be silent until it is advanced, and when signs do appear they tend to include reduced exercise tolerance, lethargy, a soft cough, faster or laboured breathing, or in serious cases a fainting episode. None of these is specific to diet-associated disease, and all of them warrant a vet visit on their own merits, but an owner feeding a pulse-heavy grain-free diet has one extra reason to take early changes seriously. The reasonable posture is neither vigilance bordering on panic nor indifference: feed a food from a maker with strong nutritional credentials, know your breed's baseline cardiac risk, and treat new exercise intolerance as a prompt to book an appointment rather than to search the internet.

Alt text: "Timeline of the FDA grain-free DCM investigation from 2014 to 2022, marking report tallies and the December 2022 pause with no recall."

How to read adverse-event data without overreacting

The FDA figures are real, but they are a particular kind of data, and reading them well prevents both panic and dismissal. They come from a passive reporting system, where owners and vets submit cases voluntarily. That has two consequences worth holding in mind. First, publicity inflates reporting: once the 2018 announcement put grain-free DCM in the news, owners and vets who already fed grain-free were more likely to look for and report cardiac problems, which can swell the count without the underlying rate changing. Second, the denominator is unknown: 1,382 reports over nine years tells you how many cases were submitted, not what fraction of all grain-free-fed dogs that represents, and without that fraction you cannot calculate a risk. This is precisely why, lacking a quantified control group, the evidence stays at the association level (AVMA, 2022). None of this means the signal is noise. It means a count of reports is a prompt for investigation, not a measured risk, and treating it as the latter is the most common error in the whole debate.

Where to read more (Grain free)

The cardiac questions, including which breeds are predisposed and what the association does and does not show, are handled in our grain-free and DCM FAQ, and the broader question of whether removing grain is ever necessary sits in the controversial ingredients FAQ. For a structured walk through the decision, the grain-free diet guide weighs the evidence by use-case, and the choosing quality pet food guide explains how to judge a manufacturer's nutritional rigour, which matters more here than any single ingredient. The underlying condition itself is defined in our entry on dilated cardiomyopathy.

The takeaway (Grain free)

The grain-free and DCM story is a case study in the difference between a signal and a verdict. The FDA counted real reports, found a real shared feature in pulses rather than missing grain, could not establish causation, issued no recall, and paused public updates without closing the file. An owner who internalises those numbers will neither panic nor dismiss the topic. They will treat diet as one variable to discuss with a professional, with the data, not the headline, as the starting point.