I recently attended a day’s training all about respiratory vs heart conditions in dogs at one of the top referral centres and delivered by the top vets in their field.

It had nothing to do with pet nutrition but covered a topic that I always find so challenging when faced with a coughing pet – is it the lungs or is it the heart causing the coughing?

golden retriever dolated cardiomyopathy grain free diets

One lecturer in particular mentioned something so interesting that I had to write a post about it to share with all of you concerned pet owners. She made a point about grain free diets being the potential cause of the rise in the extremely rare condition – dilated cardiomyopathy in dogs.

She spoke of a particular case she had been treating recently – a Dobermann with dilated cardiomyopathy who had been diagnosed at the referral centre and came for regular check-ups on his heart.

He was doing so well until his second last appointment when his owners mentioned that he had slowed down, was coughing more and his heart parameters had worsened even though he was having the required amount of medication. Upon further questioning, the owners mentioned that they had changed him onto a more expensive grain free diet. This was the only change that they had made (thinking that as it was more expensive, it had to be better for him).

The referral vet advised that he went back onto the previous diet he was having and with his last appointment, he improved considerably!

Like other concerned pet owners and vets, I had read about the rise in the very rare condition of dilated cardiomyopathy in dogs due to the increase in pets being fed grain-free diets or exotic diets promoted by pet food companies as fully hypoallergenic and healthy; when in fact they could be lacking in the essential nutrients that promote heart health.

When I worked as a vet in the 90’s, I was diagnosing feline dilated cardiomyopathy so often. Pet food manufacturers realised that this was due to a lack of taurine in the cat food and since it has been added to all cat food, the problem has not been seen since!

Taurine for Dogs (taken from an article written by Dr Jean Hofve in 2020)

Dogs make their own taurine from sulphur-containing amino acids, primarily cysteine, but also methionine. It was thought that, because they could produce it themselves, dogs didn’t need supplemental taurine.

However, it is also known that large dogs produce taurine at a slower rate than small dogs, putting them at risk for a deficiency. Genetics also play a significant role, with certain breeds and family lines being predisposed to developing DCM.

The existence of a link between taurine deficiency and DCM in dogs has been known since 1997, and the simple fact is that some dogs can’t supply their own taurine needs. Certain lines of spaniels, Retrievers (notably Golden Retrievers), and particularly Newfoundlands, are known to develop the same taurine-dependent form of DCM that had killed thousands of cats before they started adding taurine to cat food.

DCM is a common form of heart disease in dogs, especially in large and giant breeds, who produce less taurine than smaller dogs on the same diet. Diet is a likely factor in about 20-30% of dogs with DCM, for which supplementing taurine may reverse the disease. For this reason, as a vet, I definitely recommend taurine and methionine supplementing for dogs if ome cooking, as found in our Just Be Kind Supplement.

However, it may not be a specific taurine deficiency in the food that is a contributing factor in DCM. Some research suggests it may be insufficient cysteine that limits the dog’s ability to produce taurine. Dogs make cysteine from methionine, and taurine from cysteine. Any weak link in the chain of methionine, cysteine, or taurine could be problematic.

In early studies in the US, most of the dogs with DCM were eating lamb and rice dog foods. Lamb has a relatively low level of sulphur-containing amino acids compared to chicken and other poultry. Another study found that dogs eating foods containing beet pulp had lower blood taurine levels.

Possible reasons for low blood taurine levels in dogs fed an otherwise “complete and balanced food” include:

  • Differences in protein digestibility and bioavailability may limit available precursors
  • Interference with reabsorption of taurine-containing bile acids in the gut so that more taurine is excreted
  • Interaction of food and/or food form (tinned vs. dry) with gut bacteria

Most importantly, of the tens or perhaps hundreds of thousands of dogs eating “boutique” and grain-free foods, only a handful are related to the problem.

The Current Situation

The FDA reported a link between DCM and “grain-free” dog foods that rely heavily on potatoes, legumes, and exotic proteins. This caught the FDA’s attention because some of the dogs were not the breeds that commonly develop DCM due to taurine deficiency, including Golden Retrievers, Labrador Retrievers, Whippets, Miniature Schnauzers, one Shih Tzu, one Bulldog, and an unspecified number of mixed-breed dogs.

Specifically, the FDA stated that, “potatoes or multiple legumes such as peas, lentils, other ‘pulses’ (seeds of legumes), and their protein, starch and fibre” were main ingredients of the food in several cases of DCM reported to the agency. Note the careful language used in its statement: potatoes are singled out, but with regard to legumes, multiple legumes and their isolated components were included in implicated diets.

Subsequently, the FDA has emphasised that people should “not tak(e) intuitive leaps beyond what is explicitly stated in our public notice.” That is, don’t think that all legumes are problematic – just the ones specifically noted.

Unfortunately, the FDA failed to indicate whether the associated foods were dry, tinned, or both. But it’s probably safe to assume that most or all were dry foods, since that is what most dogs are fed in the US.

Based on the FDA’s statement and previous research, the ingredients most correlated with DCM in dogs and used in dog foods are:

Animal Products: Bison, Duck, Lamb, Kangaroo, Salmon, and Venison
Plant Products: Barley, Chickpeas, Beans, Lentils, Peas, Potatoes, Rice/Rice Bran**, Tapioca
** Previous studies found taurine deficiency in dogs eating diets containing rice or rice bran

While it was not named by the FDA in this situation, beet pulp is known to decrease taurine status in dogs under some conditions.

The FDA also suggested that food made by small “boutique” manufacturers were more likely to be problematic.

It’s odd that this problem should occur now, even though potatoes have been used in dog food – particularly “hypoallergenic” formulas – for decades. Even worse, many such foods also include lamb or other listed ingredients as the primary or sole animal protein. Hill’s Science Diet d/d lists potatoes, potato starch, (venison, salmon, or duck), and potato protein as its first four ingredients. One would think these foods would be particularly dangerous, but there is added taurine in these foods. Vegetarian and vegan dog foods include both taurine and carnitine. Clearly, this issue was not hard to anticipate.

Of course, correlation does not equal causation, and there may be other factors involved. There are dozens of grain-free dog foods on the market, and without knowing which brands were involved, it’s impossible to know for certain which ingredients are at fault.

Unfortunately, some media reports have focused on legumes, even though potatoes are a far more common pet food ingredient. Legumes are very nutritious, and if used properly, can be a very healthy dog food ingredient.

Many “boutique” grain-free diets contain two or more of the ingredients noted by the FDA. For example, several salmon-based foods also contain potatoes and/or beet pulp; another lists kangaroo, kangaroo meal, peas, chickpeas, pea flour, red lentils, and green lentils as its major ingredients. If kangaroo, like lamb, is borderline on taurine, the combination of five legumes could easily outweigh the meat, and limit a dog’s ability to produce taurine. Several other foods list up to five legumes/derivatives, sometimes in addition to potatoes or a listed lower-taurine meat like venison or lamb, as major ingredients.

As with cat foods, some dog foods are inordinately high in plant-based products and not so much meat. Certainly, plant proteins are often used to increase total protein and decrease cost in many dog foods. It is expensive to add in extra taurine and methionine to any pet food, which is possibly where all of the problems lie!

Ingredients are listed by weight on the label. Using multiple legumes, potatoes, or fractions thereof (a practice referred to as “splitting”) allows a company to include far more plant protein than meat protein, while allowing the named meat to remain at the top of the ingredient panel. So, it may not be legumes that are the problem. Rather, it may be an overwhelming number of legumes.

Most small-manufacturer and grain-free diets are relatively high in protein, but the proportion of plant to animal sources may be a crucial factor for those foods implicated by the FDA.

There are other factors that could affect dogs’ blood taurine levels. Perhaps there is some intrinsic factor in legumes and potatoes that is acting as an “anti-nutrient” – or something is happening during processing – that is causing taurine in these foods to become unavailable. Taurine from fish is diminished by heat processing (around 30% is lost). Type of food (dry vs. canned) alters taurine bioavailability in cats through the action of gut bacteria, perhaps this is true for dogs as well. These possibilities have not been explored at all in dogs.

What Should You Do?

It is important to note that not all dogs with DCM – and not even all the dogs with very low blood levels of taurine – responded to taurine supplementation. Conversely, many of the sick dogs had normal blood taurine levels. One study concluded that “there was no clear relationship between low (whole blood taurine) and presence of DCM.”

The association is far more complicated than simply blaming the problem on legumes, as many news reports have done. There is clearly a relationship between genetics and one or several of the 15 above-listed ingredients, as well as the food’s overall content of methionine, cysteine, l-carnitine, and taurine, that is causing DCM. But no one has any idea which factors are problematic, and in what amounts or combinations. It is likely that multiple factors are involved. For example, it may take multiple listed ingredients, plus a genetic predisposition toward DCM, to develop the disease.

It does seem likely that in a product containing sufficient animal protein, taurine levels will be adequate. If a food has an animal protein at the top of the ingredient list, but also contains four or five plant proteins that – in reality – constitute the majority of total protein, thus diluting and short-changing the taurine, then that may be the real problem.

One thing that is clear from all this is that the AAFCO needs to revisit its Nutrient Profiles (which are based on research published prior to 2003) and either (1) increase the minimum for methionine, (2) increase the minimum for methionine-cystine, and/or (3) add a notation that cysteine and taurine are essential – or at least conditionally essential – amino acids for dogs.

Most importantly, of the tens or perhaps hundreds of thousands of dogs eating “boutique” and grain-free foods, only a handful are related to the problem.

However, it would be helpful if pet food manufacturers would test for the four key amino acids to ensure that levels are sufficient for all dogs, or simply supplement taurine in food for dogs, as they already do for cats.

If one is feeding a potentially taurine-deficient food, it would be a good idea to give supplemental taurine at up to 1000 mg per day for every 20kgs of the dog’s body weight. Taurine, which usually comes in capsules of 500 or 1000 mg, is very safe even at extremely high doses. It also has very little taste and is relatively easy to give.

(taken from an article written by Dr Jean Hofve in 2020)

just be kind vegan dogs