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(The following is borrowed from Atlanta Veterinary Skin & Allergy Clinic - it is one

of the most comprehensive articles on DCM and grain free dog food.)

I would imagine that many of you have heard or read about recent concerns

regarding grain free diets and the potential for heart disease in dogs eating them.

This article is designed to sort out fact from conjecture and answer some of your

questions. The concern is that Grain Free Diets may lead to taurine deficiency

and that taurine deficiency has been linked to Dilated Cardiomyopathy (DCM) in

dogs. In full disclosure, I am a Board Certified Veterinary Dermatologist with 35

years of practice experience and I have a Masters degree in Nutrition and Skin. I

am not a boarded Cardiologist or Nutritionist. I do prescribe limited ingredient

diets for my food allergic patients and many of these are grain free. Prescription

diets are nutritionally balanced; some over the counter limited ingredient diets

may not be.

Certainly opinions abound on the merits of a raw diet, or a grain free diet, or

paleo, gluten free, etc etc. There is A LOT of information out there - some

accurate and some misleading. And even when you do "research" on the internet,

how reliable is the source of the information? What you should know is that

there has never been any truth to the statement that grains are harmful to our

pets and even less evidence (if that is possible) that grain free diets are healthy.

The choice to feed grains or grain free is simply a choice. That's all. There is no

perfect diet for every pet. Not one. However, I will do my best to present the

FACTS regarding this particular issue . At the end, I will provide my opinion and

reasonable plans of action that should alleviate some of your concerns about

your best friend's best dietary health. Let me know your thoughts!

So, what is “THE ISSUE” ?

In early 2018 several cases of Dilated Cardiomyopathy (DCM) were recognized in

dogs that do not typically have the disease. A pattern emerged that several of

these dogs were being fed a grain free diet. ANECDOTAL reports implicated

some grain free diets or diets containing legumes (peas, lentils, chick peas,

beans, etc). A suspicion that these diets may lead to taurine deficiency and the

development of dilated cardiomyopathy (DCM) raised the alarm among veterinary

cardiologist. Some of these dogs were tested and found to have low or very low

blood levels of taurine. Since taurine deficiency has been determined to be a

cause of DCM, these dogs were placed on a taurine supplement and the diet

changed. Some (but not all) saw signs of clinical improvement. What is

interesting is that this same issue arose in the 90’s in regards to lamb and rice

(rice bran) diets. Those diets were determined to be taurine deficient. A recent

article in the New York Times provides a decent overview of the issue

ml ) .

The concern is that DCM is occurring in breeds not typically genetically prone to

the disease. As of July about 150 cases have been reported through the

veterinary Cardiology community. On July 12, 2018 the FDA issued a public

notification about the agency’s investigation into reports of DCM occurring in

dogs eating certain pet foods containing peas, lentils, other legume seeds, or

potatoes as main ingredients.

Several veterinary cardiologist across the country are in the process of

evaluating the issue and have yet to draw a direct causal association among

grain free diets, taurine deficiency, and DCM. The fact is the veterinary medical




suspicion for the FDA to issue a warning however, and that is significant. This is

a serious disease so until we know better, pet owners that are feeding this type

of food need to be informed.

Several articles have appeared in lay publications that have brought the issue to

the public.



My opinion is that the titles of the articles are misleading. It Is important to get a

handle on the facts and then make a choice that is in the best interest of your pet.

There are no recalls yet and millions of dogs seem to have eaten these diets for

years with no obvious adverse effects. But it is scary to think that a limited

ingredient diet, carefully selected with your pet’s best health in mind, could

somehow make your pet sick.

What We Do Know

First Question: What is a grain? Well, in pet foods it includes corn, soy, wheat,

barley, oats and rice. Grains are used in both dry and canned pet food to provide

carbohydrate, protein and fiber. They are used to help bring into balance the

nutrient profile of a specific diet.

What does grain - free mean? It means the food should be free of grains,

although some foods labeled as grain free contain barley - which is a grain. The

term also implys that having grains is somehow bad for your pet. Grains are not

bad or good. They are a type of food.

“Grain-free” is a marketing term rather than a health term. There are no data that

show that a grain free diet has any health benefits for dogs and cats over more

traditional diets. NONE. Grain free diets for pets (and us!) is a huge part of the

marketing conversation around what is “healthy”… and we have bought into this

craze hook, line and sinker. We reach for these diets because they are billed as

more “natural” and less likely to cause health problems and allergies. “Grain

Free” is NOT that! It is simply a food choice and choices may have

consequences if we are not fully informed when we make them. Too much of

anything is not healthy. There is nothing right or wrong with a grain free diet and

there is no nutritional benefit to feeding one either. Either way is fine as long as it

is nutritionally balanced and complete. If you wish to feed a grain free diet, just

be sure to do your homework and know that your choice is a balanced and

complete diet.

What About the Food Allergic Pet

In my practice, food allergy is a common problem. FOOD ALLERGY IN DOGS

AND CATS is caused by your pet’s immune system misidentifying a food protein

(meat or non-meat) as foreign and potentially harmful, then OVER reacting to it

leading to an adverse reaction (itching, redness, rashes, vomiting, diarrhea,

secondary ear and skin infections, etc). The culprit can be ANYTHING that has

been a part of your pet’s current or past diet INCLUDING animal proteins (meats,

poultry, fish, eggs, cheese) and plant proteins (peas, soy, corn, rice, barley, oats,

wheat, potato, sweet potato).

There is no reliable evidence that grains are harmful. In fact grains provide

valuable nutrients (vitamins, essential fatty acids, and fiber), sometimes in a form

that is easier to digest than some meats. What surprises most pet parents is

that grains are UNCOMMON food allergens. Most of the time the allergy is

caused by the meat/fish/poultry component. The most common animal protein in

both grain free and grain containing diets are poultry (chicken, duck, turkey), fish

and egg AND these are the most common causes of food allergy in dogs and

cats. Over the years I have seen a growing number of rice and potato sensitive

patients as well. Why? Because these ingredients have become common in pet

foods. I have never seen a pet with a wheat allergy. In fact wheat is rarely in pet

diets - (never has been), but it does show up in treats. Of particular note is the

fact that gluten intolerance with GI signs just does not occur in dogs and cats. It

has only been documented in the literature in one inbred family of Irish setters

and never in cats - that’s how rare it is.

What is Dilated Cardiomyopathy (DCM)

Canine DCM is a disease of a dog’s heart muscle and results in an enlarged heart.

As the heart and its chambers become bigger, the muscle wall becomes flabby

and thin, and it becomes harder for the heart to pump blood. As a result, the heart

valves may leak, leading to a buildup of fluids in the lungs, chest and abdomen.

In the final stages signs of congestive heart failure develop (distended abdomen,

exercise intolerance, increased breathing effort, cough, fatigue, collapse ). DCM

is a congenital condition in some breeds. In those where the condition is not

congenital, heart function may improve where taurine deficiency has been

identified and the deficiency treated.

The interesting thing is that dogs can make all the taurine they need if given the

needed precursors (methionine and cysteine) in food . But some dogs develop a

deficiency even when they have been provided plenty of taurine. It is also

important to note that not all dogs with taurine deficiency go on to develop DCM.

Every pet is different.

What is the breed profile

The genetic predisposition to develop DCM occurs in a few large and giant breed

dogs, such as Great Danes, Portugese Water Dogs, Boxers, Newfoundlands, Irish

Wolfhounds, Saint Bernards, Golden Retrievers and Doberman Pinschers. The

American and English Cocker Spaniels are also predisposed. Cases that have

been reported to the FDA have included Golden and Labrador Retrievers, French

bulldogs, schnauzers, as well as other small breeds and mixed breed dogs.

What is Taurine'

Taurine is an amino acid that is used in the body for a variety of vital functions. It

is found in high concentrations in the eyes (required for retinal photoreceptor cell

survival (vision), intestinal tract, bile, and in muscle including the heart. It plays a

role in neurotransmission (GABA receptors in the brain) and stabilization of fluids

within cells. It is an essential nutrient in cats because they can’t make it. A

healthy heart is supported as long as the precursor amino acids are in the diet.

Dogs can make it out of the sulfur containing amino acids (methionine and

cystine) so typically it is not added to dog foods.

What causes a deficiency in taurine?

The precursor amino acids as well as taurine itself are in very high

concentrations in muscle meat, fish and eggs . It is absent or exceedingly low in

plants. Vegetarian diets without added taurine are likely to be deficient diets. In

addition, legume based diets (peas, beans) and potato based diets that are not

properly formulated with other amino acid sources (eg. don’t have taurine added

or enough meat/ animal protein to provide the precursor amino acids) may lead to

taurine deficiency. What may have occurred with some grain free diets is that

although the protein requirements established for dogs were met on paper, the

need for sulfur containing aminio acids was overlooked.

There are a lot of OTHER possible conditions that may lead to Taurine deficiency.

These become more obvious if the diet is borderline deficient to begin with.

● Taurine loss through preparation procedures (boiling or basting looses

taurine; baking or frying retains taurine)

● Reduced bioavailability (fiber content affects digestibility)

● Increased fecal loss - GI bacteria that interact with bile salts can result in

loss of taurine in the stool

● Dogs with lower energy needs (the larger breeds) may not eat enough of

the precursor AA to make enough taurine.

Why there is concern that a Grain Free diet could lead to taurine deficiency

The issue really is not whether the diet is Grain Free or not. The nutrient profile

(what the diet is made of) is the key. The liver does not care about the source of

nutrients per se, but it does require certain types of nutrients to make taurine.

Dogs require sulfur based amino acids, which come from animal protein, in order

to make taurine. If a grain free diet provides the bulk of its protein from plants

(pea, potato, etc) and does not have enough of the precursor amino acids to

make taurine, the diet will be deficient. In addition, the fiber content,

bioavailability of nutrients (how well the body can extract nutrients from food),

bacterial profile in the intestinal track (good gut bacteria help process and

transport the nutrients we eat), and energy requirements of the dog all play a role

in how taurine will be made and used. There are diets formulated with pea and

potato protein that are just fine. But if a diet is high in plant fibers which impact

bioavailability, then the diet may be deficient on an as-fed basis even if the diet

appears to be adequate. Just reading the label is not going to give you all the

information you need to make a decision. You need to ask the manufacturer. A

food with lower bioavailability may test at a lab at a higher level than what the

body can actually digest/absorb. There have been a few diets that have been

specifically targeted as being deficient but no diets have been recalled.

I know the raw food advocates are screaming that this does not happen with a

raw diet. But here is the truth. Raw is no healthier than grain free or gluten free


balanced and complete. The body does not care if a food is raw or cooked, just

whether it has access to the needed building blocks. It is true that processing

can change the nutrient profile and deplete some key ingredients. Knowing how

to make the necessary adjustments in any formulated diet is key to insuring that


Why didn’t anyone know about this before?

I will borrow a quote by clinical nutritionist, Dr. Lisa Weeth from the Veterinary

Information Network, as I think her comments sum it up best:

“I suspect that [the cause for the deficiency leading to DCM] will be similar to the

cause for taurine-deficient cardiomyopathy in dogs fed lamb meal and rice with

rice bran diets in the late 90s/early 2000s. It could be an anti-nutritive property of

peas and other legumes, but as the larger pet nutrition companies …. have been

using pea protein in some of their therapeutic diets successfully for decades

(without creating taurine deficiency) I suspect that it will come down to specific

diets and manufacturers that use poorly digestible dietary proteins (plant and

animal), low total sulfur-amino acid levels in the diet, increased dietary fiber

causing enhanced loss of [taurine] in stool, and low conversion of cysteine to

taurine in large and giant breed dogs. [The Veterinary Nutrition Community] was

aware even if certain "premium" dog food manufacturers were not.

…….the increase in popularity and sales growth of "grain-free" diets triggered a

number of "premium" diet manufacturers to substitute pea protein and other

whole legumes into extruded dog foods in place of wheat, rice, and corn, but

since these pet food marketing companies do not [work with Veterinary

Nutritionist or have their post production diets analyzed for nutrient profiles],

they didn't know what they didn't know. “ Lisa P. Weeth, DVM, MRCVS, DACVN

( quote from a discussion on Veterinary Information Network )

What do I need to do if I am feeding a grain free diet to my dog

First, DON’T PANIC! If your pet is not food allergic or the diet you are feeding is

out of choice rather than necessity, change the diet ! There really are way too

many good choices out there. Pick one that is not grain free and is made by a

company with a long track record of producing good quality diets that they have

tested. The World Small Animal Veterinary Association (WSAVA) has established

very specific nutritional assessment guidelines for pet foods. The following

companies/ diets are known to follow these guidelines (but sadly even that can

change): Purina brands: ProPlan, Merrick, Chow, ONE, etc.; Hill's brands:

Science Diet, Healthy Advantage, etc.; Mars brands: Royal Canin, Iams,

Eukanuba, Nutro, Pedigree, etc.

If your pet is food allergic, then hopefully diet challenges have revealed what can

and cannot be fed so that we can find an appropriate commercial diet for your

pet. If you have not completed diet challenges, now is a good time to do it. It will

provide vital information required to make a change that will not trigger the food


Have your pet’s blood tested for taurine levels . If the levels are normal, the diet is

fine and you have nothing to worry about. If the levels are low, it is advised to

have chest x-rays and an Echocardiogram done to assess the function of the

heart. If those tests are normal, just change the diet or add a supplement (or

both). Doses and selection of a supplement should be done under the direction of

your veterinarian. A follow up blood test should determine if the adjustments

were adequate. Having low taurine levels on a blood test does not automatically

mean your pet will develop signs of heart failure or DCM. It does mean that they

are at a HIGHER RISK of developing one of the conditions associated with taurine

deficiency. Steps should be made to reduce the risk.

A note about supplements. A study published in 2009 ( J Am Vet Med Assoc.

January 2009;234(2):209-13) evaluated 11 commercially available taurine

supplements. While 10/11 met label claims of content, disintegration of the

product was observed in 4 of the 5 tested. Stability over time could be an issue.

If your pet is food allergic and it took a long time to find a diet that did NOT

provoke an adverse reaction and that diet is grain free, and you do not want to do

the blood test, then let’s talk about the option of adding MEAT or EGGS to the diet

(only if they are not allergic to it). Alternatively, you can add a vitamin

supplement containing methionine and cysteine to make sure your pet’s diet

contains the building blocks necessary to make taurine and other nutrients that

rely on the sulfur containing amino acids for normal function. Amino acid or

taurine supplementation require direction from your veterinarian.

Here is what we know:

● Taurine is an essential nutrient obtained directly or indirectly from the diet.

Most dog foods do not have it added because dogs can make it from meat

protein and methionine and cysteine amino acids(sulfur containing AA). If

the diet lacks these building blocks and is not supplemented with taurine,

then a deficiency may occur

● In many grain free diets, legumes are used to provide the carb (starch) but

also protein and fiber. The amount of protein is listed on the label, but you

cannot tell which ingredients are providing various proportions of nutrients

from an ingredient list. Legume protein is low in sulfur amino acids

(methionine and cystine - the precursors for taurine synthesis) so diets

high in legumes may result in a deficient diet.

● Some fiber sources seem to lead to increased fecal loss of taurine and may

cause a deficiency

● We know that some breeds, like the Golden Retriever, are susceptible to

taurine depletion and DCM for reasons we don't understand. Some were

fed grain free while others were not. In other breeds fed grain free diets

diagnosed with myocardial failure, taurine deficiency has not been found.

● Large breed dogs with lower energy needs may not eat enough to get

adequate amounts of taurine or its precursors from the diet especially if the

diet is already borderline

We do not fully understand the effects of fiber and protein on good bacteria in the

gut or how that impacts taurine bio-metabolism. We also do not know what

causes increased fecal losses, or why larger dogs have lower synthetic rates for

taurine. We do know that if the diet is marginal and/or if fecal losses are higher

than “normal" then our pet will become deficient in this essential nutrient. Seems

like there is a lot we (the veterinary medical community) just don't yet know. But

there are some really bright minds that are working on getting an answer. In the



What can you do?

Know what's in your pet's food. It sounds like a lot of work and you should not

need to do it given the cost of pet foods these days. But knowledge is power. The

most efficient way is to ask the manufacturer . If they can not provide written

documentation of analysis of their food, chances are they have not done it. There

are too many choices out there for you not to pick one that you can be confident

is truly a healthy diet.

Adding meat to the diet or rotating the food is one way to potentially correct a

diet deficient in taurine (and other nutrients!) because taurine is naturally

abundant in meat, eggs and seafood. But how much is enough? Each pet is

different. The key is to provide adequate sources of the amino acid precursors,

methionine and cysteine. Muscle meats – including tongue and heart, eggs, and

seafood provide huge amounts of both taurine and their precursors - and frankly

it does not matter whether it is cooked or raw. But it should not be added “willy

nilly”. So consult your veterinarian to know what is right for your pet.

If you have a favorite diet that you want to continue to feed, then ask the

manufacturer to provide documentation for their nutrient analysis. There are also

tools that will allow you to have a home cooked diet analyzed for balance

( is one site you may be able to consult). Just do your homework.

Here is a summary with my opinion and final thoughts

● Dogs can MAKE taurine from key amino acids present in most pet foods.

Most dog foods are not supplemented with taurine for this reason. If sulfur

containing amino acids (methionine and cysteine) are not available in the

dog food, a dog can become taurine deficient over time.

● Plant proteins lack sulfur containing amino acids

● It’s not the grain free part, but the ratio of ingredients – whether there are

enough “building blocks” in the food for a dog to make taurine and how the

body uses them – that create the challenge

● If a diet uses mostly pea or potato to comprise the protein component, and

only a little salmon, duck, pork, or whatever animal protein it says it has,

then the diet may be deficient in the building blocks

● You may be able add meat to the diet, or methionine or taurine supplement

to restore balance if the diet is not balanced

● Unfortunately the nutrient profile written on the bag only gives part of the

story. This article gives you specific questions to ask the manufacturer if

you do wish to dig deeper.


... and this article is a primer on how to read pet food labels.

● The grain free diets out there that are deficient are that way probably

because they weren’t tested after they were made and the manufacturer

didn't know they needed to. If they haven’t been tested, the company can't


● To know for sure whether your pet is taurine deficient, have a blood test

done that measures taurine levels in the body. It is a simple blood test and

will provide valuable information on the effects of the grain free diet you

are feeding.

A diet can be full of great-sounding ingredients, and still not meet your pet's

nutritional needs. The AAFCO (American Association of Feed Control Officials)

statement, otherwise known as the "nutritional adequacy statement" tells you

whether the food is designed for a dog or a cat, and whether that dog or cat is a

growing, pregnant or lactating, or an adult at maintenance. It means the diet

meets the minimal standards, not optimal standards. A company can claim that it

meets AAFCO standards, but you have to look deeper to understand HOW they

are able to make the claim. Some just plug their ingredients into a computer

analyzer - which does not take into account how processing affects the

physiologic impact of the nutrients. Feeding trials are the gold standard but are

not commonly done.

My bet is that the grain free/ taurine deficiency/ DCM issue is going to have less

to do with grains, legumes, or potatoes per se but will point to the need for good,

well documented balanced nutrient profiles for pet foods.

What may emerge from this controversy is a new standard for balanced pet

foods. It may put some of the smaller boutique foods out of business because

unfortunately they may not be able to afford the analysis. Still, if a pet food is

going to make health claims, it needs to be able to back it up with sound well

documented evidence that the food is balanced and complete. If your best friend

does not have a food allergy or some medical reason to be on a limited diet, the

best advice may be to change away from a "grain free" diet and go with

something more long term "tried and true" until we figure this out.

I hope this helps! If you want to discuss trying a different diet, let’s discuss at

your next visit or shoot me an email.

Here's to your pet's best health!

Dr. Pat

Atlanta Veterinary Skin & Allergy Clinic, PC - 2022

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