On July 12, the Food and Drug Administration (FDA) issued an advisory alerting U.S. pet food companies, veterinarians, retailers and the public that it was investigating a recent outbreak of atypical cases of canine dilated cardiomyopathy (DCM) with a possible link to pet food ingredients used in popular grain-free and similar products.
Naturally, this announcement sparked a lot of concern and discussion in the industry, so Petfood Industry held a webinar on September 4 to provide an update on FDA’s investigation. Though we organized it quickly, confirming the speakers and announcing it only about two weeks before the broadcast date (which was the morning after the U.S. Labor Day holiday, to boot), we had record numbers of registrants, participants during the live broadcast and questions and comments posed. That just illustrates just how much this issue is resonating.
Martine Hartogensis, D.V.M., deputy director at FDA’s Center for Veterinary Medicine’s Office of Surveillance and Compliance, was one of the webinar speakers. She explained the events leading up to and since the advisory.
FDA report on DCM investigation, number of cases
Six to seven months ago, a group of veterinary cardiologists informed FDA that they were seeing a pattern of dogs showing signs of DCM that did not belong to breeds known to have a genetic predisposition to the condition, Hartogensis said. There were about 150 cases reported by the cardiologists, and most of the dogs had been eating grain-free dog foods as their sole diets.
This prompted FDA to check its database for similar complaints reported directly to them, of which they found about 30. When they studied those cases more closely, they saw similarities in the types of foods the dogs were eating. At that point, they also measured the level of taurine in both the foods and the dogs, since taurine deficiency has been shown to lead to DCM, at least in cats. FDA did not find low taurine levels in the foods in those 30 cases but did in some of the dogs.
The advisory came next, which Hartogensis characterized as a mechanism for her agency to get more information, including about affected dogs’ taurine status, and to see if there were other cases not reported or known to the veterinary cardiologists.
The advisory resulted in 149 new cases overall of DCM reported to FDA:
- 145 cases involving 160 dogs (some cases involved more than one dog) and 39 deaths; these cases were all from 2017 and, mainly, 2018;
- Four cases involving eight cats and one death; these were all older reports, dating back to 2015 or 2016;
- With the new cases, about 90 percent of the dogs had histories of eating diets labeled grain free — not just grain free, Hartogensis emphasized, but diets also containing a high proportion of legumes and pulses (peas, lentils, chickpeas) or potatoes.
FDA partners with a network of about 40 veterinary diagnostic labs nationwide to help it investigate complaints and issues like this, Hartogensis explained, and they are now doing a prospective study with that network focusing on several things, including taurine. “Of course, dogs can make their own taurine from cystine and methionine, so we’re looking at all three — taurine, cystine and methionine — in the foods and in the dogs as well,” she added.
Breakdown of cases and what dogs were eating
The webinar included two other speakers: Lisa Freeman, Ph.D., professor at Cummings School of Veterinary Medicine at Tufts University; and Greg Aldrich, Ph.D., president of Pet Food & Ingredient Technology Inc. and research associate professor and pet food program coordinator at Kansas State University. They provided clarification and additional information related to their areas of expertise.
For example, Freeman, who is board-certified by the American College of Veterinary Nutrition, emphasized that no one should think of this situation as being just about a taurine deficiency or just about grain-free diets. She has communicated with veterinary cardiology groups and obtained information from them showing three different groups of dogs with DCM now:
- Standard cases in breeds typically predisposed to the condition
- A new group of dogs with taurine deficiency and DCM, of both typical and atypical breeds — and their conditions have improved with a change in diet.
- Another new group of diet-related cases, but these dogs (again of typical and atypical breeds) are not at all taurine deficient. This is the majority of the cases, Freeman added.
“Clinically, most of the cases we’ve seen or that have been reported involve grain-free diets, but not all,” she commented later during the question-and-answer part of the webinar. Some featured other novel, exotic ingredients or fell into the category of what she called “boutique” diets, meaning specialty pet foods or ones from smaller pet food companies.
“It’s important to keep our minds open to what the cause of this could be until we truly understand it,” Freeman said. “For taurine deficiencies, there could be genetic causes, an absolute deficiency of taurine or its precursors in the diet, or reduced bioavailability of those nutrients in the diet. Even altered taurine metabolism in the intestine due to interactions between the diet and microbes in the intestine.”
Correlations and associations, no direct studies in pets
Aldrich echoed some of Freeman’s comments regarding interactions in the intestine, as well as some of the novel ingredients in the diets involved and the lack of publicly available research on their use in pets, compared to the relatively much larger amount of research on more traditional ingredients.
“We had 50 years of research on corn and wheat and soy as ingredients in foods for pets, and we had a lot of understanding about them,” he said. “But when you get into some of these ingredients, and I’ll point to even peas and lentils, there’s a fair amount of research on those for human nutrition, but you could count the number of research studies on one hand on the use of them in the dog and cat. That doesn’t mean the companies haven’t done those research projects internally, but we just don’t see those in the public domain.”
Aldrich provided some data from available pet food research but cautioned it did not provide much direction or guidance for the current DCM situation. “Much of today is speculation,” he continued. “We’re seeing correlations and associations, but there have been no direct studies of these legume seeds and their effect on taurine.” He added that the jury is still out on the role, if any, of the novel proteins and legumes in the diets associated with these new cases of DCM.
The same goes for the other carb sources implicated, tubers/potatoes. Aldrich said he could find no evidence to show that potatoes would be involved in depletion of taurine. Further, they’re not really a net contributor of protein or amino acids to the diet. “So there must be some other factor associated with tubers, potatoes specifically, that could cause some mis-formulation or oversight in regard to bioavailability of key building blocks (amino acids).”
Aldrich also pointed out the significant influence of today’s pet owners, who want pet food products more like their own diets. That creates challenges for pet food manufacturers and nutritionists, especially with popular categories like limited ingredient diets, to ensure that all the necessary nutritional components are in the foods.
“This world of pet nutrition has gotten much more complicated. And at the same time, some pet food companies, in response to pressure from animal activist groups, have diminished the amount of validation they do with their diets,” Aldrich said. “Maybe this is an opportunity to look back across our nutritional platforms and make sure we’re properly balancing the diets, validating their nutritional efficacies and putting products into the marketplace that we truly have confidence will support the animal’s nutrition.”
Aldrich summed up the current situation by classifying it as classic amino acid nutrition, saying it’s his hunch that the industry and FDA will finally resolve this by finding that the problem is some sort of under-formulation related to the bioavailability of key amino acids like methionine and cystine.
Will collaboration lead to much-needed pet nutrition research?
Though U.S. pet food companies may sometimes be at odds with FDA, industry and government also find the need and motivation to work together at other times — and this seems to be one of them. “We’ve been working very closely with our pet food industry counterparts,” Hartogensis said. “We came to them actually before we issued the advisory to notify them we were seeing this issue. They really put forward a great effort not only to look at the ingredients but also the formulations of the diets, and we’ve asked them to do that as well, because that’s not information we get.”
Upon questioning, she clarified that this collaboration was mostly through the Pet Food Institute, which represents about 90 percent of the U.S. pet food industry. (Aldrich did point out that some of the smaller companies that might be most affected by this DCM issue may not be members of the association, which is one reason we held the webinar.)
Any level of collaboration is positive, and while the issue is not likely to be resolved in the near future, at least investigations are under way. Perhaps this situation will spur a drive for funding of more in-depth research on newer pet food ingredients and other under-studied aspects of pet nutrition.