New Diet-Associated DCM Study: Feb 2021

February 19 2021

Another retrospective study (Walker et al. 2021) concerning dilated cardiomyopathy in dogs was made available for pre-proof access, meaning that the article has been peer-reviewed and accepted for publication, but will undergo some further editing/formatting for final display in the journal. This research, published in the Journal of Veterinary Cardiology, can be accessed with a subscription or single purchase, but is otherwise not available to the general public.

The study itself is somewhat similar to the paper published in December (Freid et al. 2020). It is a retrospective analysis of dogs diagnosed with DCM and CHF (congestive heart failure) at NC State University College of Veterinary Medicine between 1/1/2015 and 07/10/2019. Dogs were excluded if their diet history was unknown. The analysis divided dogs into two groups based on whether their diet was grain-free (GF) or grain-inclusive (GI) at the time of diagnosis. Dogs eating GF at the time of diagnosis were switched to GI as part of the treatment. They're therefore referred to as pGF (prior grain-free). The authors further divided the pGF group based on the length of time a GF diet had been consumed (6 months - 2 years, 2-3 years, and 3+ years).

The findings of this study are consistent with previous research, providing further evidence that grain-free diets are associated with a lower mortality, reversible form of DCM, which in turn is associated with improved outcomes following diagnosis. This study does not provide insight to the exact etiology of this observation, but reinforces the need for continued investigation. The authors acknowledge several limitations, including small sample size, and encourage further research.

Summary of Data:

67 dogs met the inclusion criteria, 43 eating GF and 24 eating GI.
- 23 breeds were represented, 19 in the GF group and 11 in the GI group
  - Great Danes, Dobermans, and Labrador Retrievers were most represented in both groups, 18/43 (42%) in GF and 16/24 (67%) in GI.
- Age varied significantly between groups, with GF median age of 6 years and GI median age of 9 years

21/43 (49%) GF dogs died and 19/24 (79%) GI dogs died during the study period.
- The effect of diet on survival was not statistically significant when considered overall
Survival was also assessed in the context of dogs that lived at least 8 days following initial diagnosis, to consider the impact of treatment therapy on dogs that lived to undergo it.
- For these dogs, previous diet was significantly associated with survival, with pGF dogs that switched diet having better outcomes than dogs eating GI at time of diagnosis
  - Within this group of dogs that survived at least one week, median survival time was 465 days for pGF and 263 days for GI.
  - Consuming GF diet for a longer time prior to diagnosis was associated with greater mortality (risk of death).

On average, pGF dogs reduced medication doses over time while GI dogs increased or maintained medication doses over time.

There was a significantly greater decrease in LVIDdN (diameter of the left ventricle of the heart) over time in the twenty six pGF dogs re-evaluated when compared to the seven GI dogs re-evaluated.