Research Update CHF 02661 EY5: Investigation into Diet-Associated Dilated Cardiomyopathy in Dogs

The study titled “Investigation into Subclinical Diet-Associated Dilated Cardiomyopathy in Four Dog Breeds” has resulted in 4 peer-reviewed manuscripts  published in the Journal of Veterinary Internal Medicine, the American Journal of Veterinary Research and Scientific Reports.

The results of this work demonstrated higher levels of cardiac troponin I in dogs eating grain-free (GF) dog foods or foods that have peas, lentils or potatoes in the top 10 ingredients compared to dogs eating grain-inclusive (GI) dog foods or foods without peas, lentils, or potatoes in the top 10 ingredients. Cardiac troponin I is a blood marker that indicates injury to the heart muscle and therefore this study provides information on how heart disease occurs in some dogs eating GF diets.

Additionally, we showed that cardiac troponin I decreased, and an echocardiographic (ultrasound of the heart) measure of contractility improved in dogs fed GF diets that were changed to a GI diet without peas or lentils 1 year after this diet change. This is important information because it shows that apparently healthy dogs can have subtle heart muscle injury that can improve with diet change. Therefore, this data is supportive of causation.

We also analyzed the blood of enrolled dogs to study small molecules indicative of metabolic pathways in the body. We found many differences between dogs eating GF diets compared to dogs eating GI diets and specifically found key differences in lipid and amino acid metabolism which were largely eliminated 1 year after diet change. Several unnamed compounds were identified as differentiators of diet type which will require more study before deciding if they are clinically important. Although the data from this aspect of the study did not reveal specific biochemical changes that are responsible for myocardial injury, it did highlight the marked differences that occur in the body as a result of food that is ingested. These different biochemical pathways in the blood might provide insight into underlying mechanisms supportive of disease propagation.

Our investigation into the effect of taurine on the renin-angiotensin-aldosterone system (RAAS) did not provide strong evidence that taurine is helping dogs with diet-associated DCM through suppression of the RAAS. Some dogs, however, did respond, especially those that were recently hospitalized and had high RAAS levels to begin with. Therefore, it is possible that it helps some dogs, but this area will require further study to determine if there might be other ways that taurine can benefit this disease when deficiency is not present.

We also utilized stored serum from this study to determine if there was evidence of phytohemagglutinins in the blood of study dogs and in both grain-free, high-legume and grain-inclusive, legume-free dog foods. Legumes contain phytohemagglutinins that can cause red blood cell clumping if improperly processed. Evaluation of grain-free dog foods showed that some had higher phytohemagglutinin concentrations than other grain-free ones, and higher than grain-inclusive foods that were tested, however, what constitutes a clinically important level is unknown. This data was presented at the 2023 ACVIM Forum. Several stored serum samples from dogs eating grain-free food and grain-inclusive foods and several clinically affected dogs were also evaluated. Results were not significantly different between groups.

The Principal Investigator requested and was awarded a no-cost extension with a new project end date of March 31, 2025

End-Year-5 Research Update Dr. Adin for scientific investigation of diet-associated dilated cardiomyopathy.