Attendees at the American Feed Industry Association’s (AFIA) Pet Food Conference at the 2019 International Production and Processing Expo (IPPE) heard an update from David Edwards, Ph.D., acting director of the Office of Surveillance and Compliance, US Food and Drug Administration (FDA) Center for Veterinary Medicine, on the FDA’s investigation into the potential link between certain pet food diets and canine dilated cardiomyopathy (DCM). Edwards shared that by the end of November 2018, the agency had received 290 reports of 325 dogs diagnosed with DCM and that the agency continues to receive about 50 cases to evaluate per month.

Of the 290 reports, the FDA was able to analyze 196 reported diets and of those 196 DCM reports to the FDA in which dogs were fed only a single, primary diet, approximately 90% of the 196 diets were labeled grain-free. Edwards pointed out that at this time, this data may point to a potential correlation between a specific diet and certain ingredients but that the FDA has not determined causation. However, the FDA report did mention that a large portion of the diets reported contained peas or lentils high in the ingredient list.

Following Edwards presentation, Greg Aldrich, Ph.D., research associate professor, Department of Grain Science and Technology, Kansas State University, addressed the implications these cases of DCM may have on ingredient categories. Aldrich first pointed out that the number of cases is relatively small compared to the estimated 22 million dogs in the US that are fed a grain-free diet.

Aldrich said the cases of DCM could be related to a large number of factors — genetics, size of the animal, metabolic rate or metabolic body size — and possibly DCM in a few cases could be directly influenced by diet and dietary taurine or support of taurine synthesis. However, it’s not a singular issue. Taurine synthesis involves building blocks from other nutrients, notably methionine and cysteine. Aldrich said there is a large number of interactions that occur physiologically in the liver to produce taurine and there are a whole host of other inputs from coenzymes to vitamins to cofactors such as minerals and also competing pathways that all influence this process.

Attention has been paid to the effect on taurine levels in dogs from common ingredients in grain-free diets but Aldrich said more research is needed. This is a complex topic to address because ingredients translate to nutrients and a better understanding is needed on the bioavailability of nutrients from different ingredient sources and how the nutrients cooperate or conflict.

Aldrich explained the need for careful nutrient formulation. He said the popularity of many monochromatic pet foods with single or limited ingredient protein sources lose the opportunity for complementary nutritional profiles. In addition, novel protein sources such as rabbit, salmon, duck or buffalo lack published research on the nutrient profiles of these ingredients and the bioavailability of those nutrients in pets.

Aldrich said that this issue has highlighted the need for additional studies including feeding trials, as well as amino acid and fiber evaluations. In a recently published paper in the Journal of Animal Science, researchers, including Aldrich, addressed the knowledge gaps that exist and must be answered before causation can be identified in the reported cases of atypical canine DCM. This paper points out that ingredients do not represent the nutritional composition of the diet, and therefore, nutrient deficiencies should not be attributed to individual ingredients.

A main takeaway from Aldrich’s presentation at the AFIA Pet Food Conference was to practice caution when designing grain-free diets and formulate with complementary nutritional profiles.

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