Grain Free Dog Food is Killing Dogs! The Facts as We Know Them (FDA update 2019)

Last updated 3rd July 2019 - originally published 10th August ‘18

If your dog is eating a grain free diet, if their diet contains lentils, peas, potato or even sweet potato, then you might have heard about the June 2019 FDA update on the situation with grain free diets causing heart failure in dogs.

If your dog is eating any of these ingredients, you definitely need to keep reading!


The FDA Investigation

The first thing to say is that the FDA has been investigating cases that have had an extensive workup, either by a veterinarian or a veterinary cardiologist, and who have been diagnosed specifically with dilated cardiomyopathy. That's that type of heart failure that these diets are causing.

The case numbers don't include a lot of other cases that have been reported because of a suspicion of heart failure but were not specifically diagnosed.

This means that the likelihood is that the reports that have been received are really the tip of the iceberg. There’s actually likely to be a lot more dogs affected.

The numbers are that the FDA has had:

  • 524 separate reports of heart failure in dogs

  • 560 dogs have been affected

  • 119 of these dogs have died

grain free dog food is killing dogs!

The Diets Causing Heart Failure

Diet Type

Most of these dogs were being fed at dry foods, so 88% of reports. So that's by far and away the majority of cases we're being fed a dry food, but raw food, semi moist and wet food has also been implicated. So it's not just a kibble alone causing this problem.

Affected Brands

There are a number of different brands that the FDA has named. These have all been implicated in more than 10 cases.

  • Acana

  • Zignature

  • Taste of the wild

  • 4Health

  • Earthborn Holistic

  • Blue Buffalo

  • Nature’s Domain

  • Fromm

  • Merrick

  • California Natural

  • Natural Ballance

  • Orijen

  • Nature’s Variety

  • Nutrisource

  • Nutro

  • Rachael Ray Nutrish

Not Just Grain Free

The big headline going back was that it was grain free diets that were causing the problem. It's now clear that this is not the whole picture.

The majority of diets are grain free, 91% of them in fact.

The other really big commonality is the specific carbohydrate source found in the diet. The one that is replacing the grain in most cases. This similarity is that a lot of them contain peas, lentils, peas and lentils or potato, and sweet potato.

Peas and lentils are by far and away the most common ingredient, being present in 93% of diets. In fact, 89% contained peas and 62% contained lentils. 42% of the implicated diets contained either potato or sweet potato. Many diets clearly contain 2 (or 3) of these ingredients as the major carbohydrate source.

Protein Source

As for the protein source in the diets, this is really widely mixed. There was a massive variation, with chicken, fish and lamb being the most common.

Are they involved? Highly unlikely. I suspect that they simply just represents the most common protein sources that are used in pet foods. Especially given that was such a variety in the affected diets.

Nutrient Analysis

When it comes to the nutritional analysis of these diets, there wasn't any consistent abnormality found. Low taurine is something that has been considered as a cause, but the methionine and the cystine components of these diets were found to be above the minimum levels in the vast majority of cases. These are the two amino acids that dogs then use to produce their own taurine.

Taurine doesn't seem to be an issue

Having said that though, there is a suggestion that Golden Retrievers, in particular, might be genetically predisposed to developing a taurine deficiency. This is significant because we know that low taurine levels can result in dilated cardiomyopathy.

if you’re feeding a diet that’s grain-free with potatoes, lentils or peas then stop feeding these grain free diets

What Should You Do?

So what should you do with all this information?

I believe that if you're feeding any of the named diets, or if you're feeding a diet that's grain-free with peas, lentils, potato, or sweet potato as the major carbohydrate source, then stop feeding these grain free diets.

Switch onto something completely different.

If your dog is showing any signs of heart failure, including lethargy, coughing, collapsing, heavy breathing, or you've got any concerns, then definitely go and speak to your vet. Certainly, if you've been feeding these diets and there are problems this is very important.

If you’ve been feeding one of these diets and your dog seems healthy, a vet check would still not be a bad idea.

And then finally, don't panic. There are 77 million dogs in the US, and such a tiny fraction have been affected. It's unlikely your dog will be affected, especially if they're not eating one of these more risky diets.

If you are worried and thinking of switching onto a raw diet, or you're wondering about the benefits of raw compared to kibble, then check out comprehensive article discussing all of the risks and benefits of feeding raw food vs feeding a kibble diet. You can also download the PDF below.

Keep reading to learn more about the investigation, dilated cardiomyopathy details, and the role that grains do (or don’t have) when it comes to feeding our pet dogs.


Today I wanted to discuss the announcement by the FDA that a number of grain-free diets appear to be causing heart disease in dogs that don't normally suffer from this particular type of heart disease.

Keep reading as well to learn all about the latest updates on the situation.

What is dilated cardiomyopathy (DCM)?

Now, the type of heart disease we're talking about is something called DCM or dilated cardiomyopathy.  DCM is when the heart becomes enlarged and the muscles of the heart don't work properly. As a result heart failure develops when the heart is just not able to pump blood around the body to an extent that matches the needs of that animal.

Make no mistake, DCM is serious and potentially fatal.  The reason that these cases are unusual is that normally only certain breed suffer from it.  Dobermans are a typical example. In the cases being investigated however, dilated cardiomyopathy causing heart failure is developing in dog breeds where it is not normally found.

The FDA grain free dog food announcement

The FDA announcement goes:

“The U.S. Food and Drug Administration is alerting pet owners and veterinary professionals about reports of canine dilated cardiomyopathy, or DCM, in dogs eating certain pet foods containing peas, lentils, other legume seeds, or potatoes as main ingredients. These reports are unusual, because DCM is occurring in breeds not typically genetically prone to disease. The FDA Center for Veterinary Medicine and the Veterinary Laboratory Investigation and Response Network, a collaboration of government and veterinary diagnostic laboratories are investigating this potential association." (read the full announcement here)

CLICK TO TWEET: Grain free dog diets may cause heart failure. The FDA is investigating the link.
This is what you need to know

What questions need asking?

So, what are the issues that we need to discuss?

Well, I think the first one is the fact that the number of dogs affected is really very low compared to the total number of dogs eating these diets. Now, that's not to say that this problem is not a cause for concern. This may very well be the very tip of a big iceberg, but I think it's important to put things into perspective and not have complete panic when we're only talking about a small number of dogs.

It's certainly important, and we should definitely all be paying attention to this situation.  Especially if you're feeding a grain-free diet or thinking about switching to one. But at the moment it seems to only a small number of dogs are being affected.

So the next issue is that the statement discusses a number of diets that contain pulses and other different ingredients as the main source in their diet. So, it doesn't specifically say grain-free.  Although diets that do contain lentils or potatoes and things like that as the main component of their diet typically are grain-free, this isn’t absolutely specified.

So, we don't know for sure that we're talking about completely grain-free diets, and we don't know which diets are involved.

We also don't know whether we're dealing with just one diet, one manufacturer, or whether we're dealing with multiple diets from multiple sources.

At this very early stage, the cause is completely unclear, and this is what is really being investigated.  So, there are a number of questions:

  • Is it a lack of grain (if they are, in fact, grain-free diets)? I personally doubt this is the only cause but it certainly could be. Is it just a lack of grain?

  • Is there a common ingredient that's causing these problems? Do all of these diets have one certain ingredient, that when fed in certain quantities causes DCM and heart failure in dogs?

  • Rather than a specific ingredient, have some food actually been contaminated with something that should never have been in the food?

  • Does Taurine play a role? There have also been a number of dogs that have been affected that have had low taurine levels. Low taurine is something that we know is associated with the development of DCM, or dilated cardiomyopathy. In fact most diets have added taurine to prevent this exact problem. Having said that only about half of the dogs tested so far had very low taurine levels and the other dogs have normal levels. So, a low taurine is definitely not the only story.

  • Are we, in fact dealing with a couple of different causes, both of which result in the same disease. Highly unlikely but the investigation will find this out.

So, really it's too early to be drawing any firm conclusions. It's definitely an important development and it could, like I say, actually be affecting a really large number of dogs. Heart disease can go unnoticed and un-diagnosed for quite a period of time. Over time with DCM, the heart will become bigger and the efficiency of the heart to pump blood will slowly deteriorate.  It's only when the reduction in pumping ability reaches a critical point that your dog will start to develop signs of heart failure.

DCM can be diagnosed in a number of different ways and if you're concerned about this at all, then you should definitely be getting in touch with your vet.  They will be able to advise you if there is anything that you should be thinking about doing for your dog. This may be a blood test, an ultrasound scan of the heart or x-rays. There are a number of things that we can do to check for damage or an abnormality within the heart.

Why feed your dog a grain free diet?

What this announcement also does is raise some important or interesting questions about why we're feeding grain-free diets in the first place.

It's a topic where there are a lot of myths, misconceptions and misinformation that are being thrown around. And there is a lot of marketing involved as well, with a lot of food companies, especially smaller boutique food manufacturers, really jumping on the grain-free bandwagon that has gathered momentum in the human health world.

As far as dogs go, there is absolutely no clear evidence to suggest that grain-free diets have any benefit for the vast majority of dogs.

One of the big suggestions thrown around is that grains are a source of food allergies.  In reality, food allergies themselves are actually pretty uncommon. And in the vast majority of cases, it's actually due to the protein component (the chicken, pork or beef for example) that is present in the diet.

Sure, there are a few individuals that are allergic to grain, but it's a really tiny minority.  This risk in itself certainly doesn't justify the mass feeding of grain-free diets to my mind.

The other thing that is often quoted is that wolves are carnivores, dogs come from wolves, and so dogs really can't process, can't digest, and have no use for grain in diets.  People often go a step further and claim that this grain is not only of no benefit, it is positively harmful and responsible for cancers and a whole slew of other diseases.

This belief actually ignores an long period of evolution.  The dog genome is definitely not the same as the wolf genome.  In fact the dog genome has developed to such an extent that there are a number of genes which allow dogs to digest grains to a much greater efficiency than our wolves can.  It does vary between breeds but it has been thought that this difference allowed dogs to thrive during early domestication.

Dogs aren't wolves, and they are able to digest and utilize grains, making them a valuable component of the diet. Something I discuss in more detail in my article all about healthy grains for dogs.

Are novel + exotic ingredients the problem?

The other issue with some of these grain-free diets is that, as I said before, there are a lot of more boutique or smaller food companies that are producing grain-free diets.  Not only that, they're also producing diets that contain quite novel or exotic ingredients. This might be different types of meat (such as crocodile, ostrich or kangaroo) as well as different pulses and seeds that haven't traditionally been used in pet food production.

The use of novel and exotic ingredients in itself isn't necessarily a problem.  But what it does mean is that it can be quite hard to know whether a diet is completely balanced, and whether it's being digested as would be expected.  Every different protein, every different ingredient will be digested in a different way and to a different extent. It might be that separate ingredients interact and reduce or increase absorption of different vitamins and minerals compared to our standards diets.

Also, a lot of these boutique and smaller feed companies are very unlikely to be running any long-term feeding trials to assess the quality of the diet and to assess animals that are fed on these diets for a long period of time before they are released.  Instead what they're often doing is comparing nutrient profiles between different diets and that can cause big problems.

If you're comparing one diet that contains crocodiles and lentils for example to another diet that contains chicken and rice, then, if we're just trying to get the more exotic ingredients profile very similar to the conventional diet we may run into problems.  Because digestibility and absorption will not be identical, a dog may very well end up with a nutrient deficiency (or even toxicity). It might be for this reason that we're finding a low taurine level in some of the dogs that are being investigated.

Don't always believe the hype

When it comes to pet food, we really need to be careful with marketing buzzwords. There's not really any legislation or control about the use of these terms. Grain-free diets may be promoted and more healthy and natural but are they really? Well, we don't know.  There is no evidence to support (or refute these claims). It may well be that a grain-free diet is better, but we just don't know.

Hypoallergenic is another term very often printed on food bags.  Really, unless we're talking about a very small selection of diets that we use specifically as food trials to rule out food allergies, hypoallergenic doesn't mean very much at all.  Being “hypoallergenic alone is in itself no real benefit to the majority of individuals and probably doesn’t mean what you think it does.

Also, natural, a lot of diets will claim to be natural. And really what does this mean?  I think in a lot of cases it probably doesn't mean what we think it does. And again, it's not really necessary for health. It's more of a marketing term.  A lot of these smaller brands, they really focus heavily on marketing and they produce fantastic adverts and videos and all that kind of thing (of course large companies also focus on promotion heavily as well).  This marketing can be very compelling, but perhaps the evidence behind feeding them isn't as strong as they would suggest.

So many questions...

All this is not to say that:

  • Grain-free diets aren't better than conventional diets, we just don't know.

  • It might be that feeding a home prepared, well-balanced, cooked diet is better for your dog than feeding a commercial food.

  • It might be that raw feeding is the best option when fed as a balance diet (and the majority aren’t)

  • But the fact of the matter is there's just not really any hard evidence, or compelling body of evidence, to suggest that one diet is better than the other in many, many cases.

Diet is something that it brings out a lot of passionate beliefs in a lot of people.  There are a lot of stories thrown around. "My dog was fed this food. I switched onto this food, and their health improved massively".  I'm sure you've read this kind of thing (check out my article on the Dunning Kruger effect to read more about this).

Really, anecdotes are a very poor form of evidence. In fact they're really not evidence at all.  What we need, and what would be fantastic, is some large-scale feeding trials, but they're just not available at the moment. Hopefully they will be developed in the future.  We really need to watch this space.

We certainly know that there are risks with some diets.  For example, raw feeding does come with some risks:

  • E.coli, salmonella and campylobacter are risks to both dog and owner

  • Bones, if fed, can result in tooth fractures as well as intestinal obstruction and perforation

  • Raw fed dogs may have a higher incidence of multi-resistant bacteria in their stool.

Now all of these risks of raw feeding may be negligible for healthy adult pets in healthy adult households.  In the young, old, unhealthy or immunocompromised however (dog or human), serious even life threatening disease may be a higher risk.  Raw feeding is a topic for another day but suffice to say if we have no evidence of a benefit and there are some risks (however small) we should think hard about whether it is appropriate for our dog.

Depending on the results of the FDA investigation, there may be similar concerns with grain free dog food.  Some risk without any proven benefit.

Really, there's more questions than answers, I know.  It's definitely a case of watch this space. Whatever the topic, we should try and stay well informed, and we should try and stay up to date with the latest developments and research available to us whenever possible.



Several months have passed since my original report in August 2018. I was recently reading an article from the author involved in the investigation into the link between grain-free diets and heart failure, or more specifically dilated cardiomyopathy. Here is the update in what we now know or suspect:


It’s not just grain-free diets

It's not just grain free diets that are causing this unusual form of heart disease in dogs. Certainly, grain-free diets are implicated, but there have also been cases in dogs fed either more boutique diets or diets which include more “exotic” ingredients. Both of these latter types may also contain grains as well.

Exotic ingredient foods may contain a whole range of different ingredients not traditionally associated with dog food. This might be different meats, pulses, vegetables, or a whole range of different foods that aren't traditionally found in dog food.

I think that highlights the fact that actually formulating a safe, nutritious pet food that optimizes for health (rather than just being adequate for health) is incredibly difficult. Certainly more complicated than just having the final diet analyzed for nutrient composition and signed off if it simply achieves the targets on paper.

Taurine deficiency is not the cause

Initially it seemed like half of those dogs affected had low taurine levels, a known risk factor for the development of dilated cardiomyopathy.

It now seems like it’s actually the minority of dogs that are affected which are deficient in taurine.

Raw and home-cooked diets are not guaranteed safe

Since the original announcement, a number of people have switched to either a home-cooked or raw diet for their dogs.

This is a whole other discussion but when we consider the risk of developing heart failure in isolation, the comment was that there have been cases of DCM in these dogs as well.

Based on this information, let’s update what we know about dilated cardiomyopathy in dogs. There appear to be 3 separate causes of this form of heart failure:

  • Low taurine levels

  • Genetic (Dobermans are the classic example)

  • Grain free, boutique or exotic diets - exact cause still unknown

Head over to my article running through the feeding for grains and the best grains to feed your dog.

So we know a little more about what’s going on 6 months or so after the original announcement. We still don’t have all the answers however so make sure you think long and hard about the reason you are feeding your dog a specific food (of any type).

What are your thoughts?  What are you planning on doing if you are feeding a grain free, boutique or exotic diet?  Are you having second thoughts if you were planning on changing your dog's diet?  Make sure you let your friends know too!

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