Tuesday, May 3, 2022

Trending Studies: Is Once a Day Feeding Healthier for Your Dog?

     A huge study from the Dog Aging Project (DAP) is currently making rounds in headlines and across social media for a surprising finding: dogs fed once a day score better on some health inventories than dogs fed two or three times per day. This finding may alarm pet owners, considering the vast majority of dogs in the US eat at least twice per day. The last thing anyone wants to do is harm their pet's health-- but these findings shouldn't have you rescheduling your dog's meals just yet. There are some important considerations that were highlighted by the authors but are being missed in the noise and bustle of social media.  

What is the Dog Aging Project?

    In their own words from the front page of their website, "The Dog Aging Project is an innovative initiative that brings together a community of dogs, owners, veterinarians, researchers, and volunteers to carry out the most ambitious canine health study in the world. The Dog Aging Project will follow tens of thousands of companion dogs for 10 years in order to identify the biological and environmental factors that maximize healthy longevity." This project has funding from the National Institute on Aging under the NIH, and is working with both University of Washington and Texas A&M University. 

What did they publish? 

"Once-daily feeding is associated with better health in companion dogs: results from the Dog Aging Project." Bray, E.E., Zheng, Z., Tolbert, M.K. et al. GeroScience (2022).
https://doi.org/10.1007/s11357-022-00575-7

 During recruitment for the 10 year study, owners completed online surveys. The 'Health and Life Experience Survey' (HLES) collected owner-reported information pertaining to the lifestyle and health status of enrolled dogs. A 'Canine Social and Learned Behavior Survey' (CSLB) collected information for scoring cognitive health and decline. Alongside this score, a score was generated from the HLES using a binary "yes has a condition" / "no does not have a condition" within 9 broad categories, such as skin, orthopedic, or cardiac. 

    Overall, there were roughly 24,200 responses to HLES and 10,400 responses to CSLB surveys. Of the respondents, 8% of dogs were fed once per day, and 92% were fed two or more times per day. Within statistical analysis, the authors were able to control for sex, age, breed (if purebred), and body size (if mixed breed). They also accounted for supplement administration physical activity, and history of training when assessing cognitive health. In analysis, the authors found a statistically significant association between being fed once per day and both better cognitive scores and decreased odds of having health conditions in certain categories. 

What does that mean for pet owners? 

    There are a number of considerations for this study. While it presents an interesting finding, it should be treated less as an indication for any feeding recommendations and more as an open door for informing further, more targeted research. The authors even write, "Given the limitations of this cross-sectional, observational study, the results of this investigation should not be used to make decisions about the feeding or clinical care of companion dogs." Some of those limitations that should be considered include: 

  • This survey was conducted at a point in time (luckily, DAP is a 10-year project). Based on this survey alone, it is unclear how long dogs were fed the number of times per day reported in the survey (was it their entire life, a recent change, a transient period, etc). 
    • Shifts in feeding style may coincide with diagnoses, such as feeding twice daily in order to administer medications twice daily (reverse causality)
  • Calorie intake and body condition were not reported for this survey, but previous research indicates these variables influence health outcomes. Once-daily feeding may also be associated with lower average calorie intake or appropriate body condition. Luckily, future portions of DAP will include obtaining electronic medical records that should include body condition.
  • As an owner reported survey, there are inherent limitations to how the data can be extrapolated; to some degree, this is counteracted by the sheer volume of responses.  
  • The nature of this study precludes establishing causation from the observed correlation, and any number of concurring factors that trend alongside once-per-day feeding may underlie the findings. 

    At this stage, pet owners should feel comfortable with what works best for their dog. Some dogs experience vomiting when fasted for extended periods, or don't tolerate once per day feeding due to food-seeking behaviors. These and similar factors have to be considered on an individual basis, and are best discussed with a veterinarian in the context of a patient-client relationship. There is not enough data in the area of time-restricted feeding to justify broad recommendations yet, so owners should not feel concerned that they are harming their dog by following the feeding schedule that works best for them. However, it is good to be aware that this is an active area of research, and data may emerge in the coming years that does change recommendations. 

    The authors end their paper, "We view these results as an exciting first step of an ongoing exploration on the impact of diet on companion dogs living in human environments. Given the intense interest in, and popularization of, "longevity diets" such as intermittent fasting, and time-restricted feeding, these types of studies in dogs are both timely and important. We believe these studies will ultimately offer insights into factors that promote health and longevity for both dogs and humans."

   As of right now, the best thing you can do for your pet's health is ensure that they have routine veterinary wellness visits, recommended blood work, and are kept in lean body condition (obesity is associated with numerous negative health outcomes), as scored on an objective chart. This may mean restricting calories through less food or less treats, but should be done in conjunction with a veterinarian to ensure weight loss is healthy and appropriate, as well as to rule out medical causes of weight gain.  

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Thursday, April 28, 2022

Randomized feeding trial in Labradors supports link between DCM and diet

Literature Discussed: "Responses in randomised groups of healthy, adult Labrador retrievers fed grain-free diets with high legume inclusion for 30 days display commonalities with dogs with suspected dilated cardiomyopathy." Bakke, A.M., Wood, J., Salt, C. et al. BMC Vet Res 18, 157 (2022). https://doi.org/10.1186/s12917-022-03264-x

Key Takeaway: Dogs eating a grain-free, legume-rich diet developed changes to their blood parameters after 30 days which are similar to changes seen in dogs diagnosed with DCM, which provides early evidence of potential pathology. 

Summary: In light of ongoing concerns of diet-associated/non-hereditary DCM noted in the US among dogs eating grain-free and legume-rich diets, researchers conducted a short-term (30 days) feeding trial on a small group of Labrador retrievers. These dogs were selected from a colony at the Waltham Petcare Science Institute. Prior to inclusion, all dogs had baseline blood parameters measured as well as cardiac clearance via echocardiogram with a boarded cardiologist. 5 dogs were fed a grain-inclusive, no-pulse legume diet, and 6 dogs were fed a grain-free, pulse legume-rich (60% inclusion) diet. These were experimental diets formulated for the purposes of the study. Blood work was checked on days 0, 3, 14, and 28. Additionally, urine taurine was measured. The dogs were scheduled to receive end-of-trial echocardiograms, but due to the cardiologist falling ill, only six dogs were scanned. 

Friday, April 15, 2022

Change of diet reduces measurement of heart damage marker in dogs fed grain-free

Literature discussed: "Effect of diet change in healthy dogs with subclinical cardiac biomarker or echocardiographic abnormalities” Haimovitz D, Vereb M, Freeman L, Goldberg R, Lessard D, Rush J, Adin D. J Vet Intern Med. 2022 Apr 14. doi: 10.1111/jvim.16416

Key Takeaway:
Heart abnormalities in otherwise healthy dogs eating grain-free diets can be resolved/reversed with a change of diet. This is consistent with the findings of multiple previous studies as well as clinical observations.

Summary:
    A recent study (Adin et al.,2021) revealed elevated levels of biomarker cardiac troponin I in healthy dogs eating grain-free diets as compared to dogs eating grain-inclusive diets. This biomarker has been associated with damage to cardiomyocytes, the heart muscle cells. It was proposed that elevations of that marker in dogs eating certain diets may be attributable to low-level cardiac damage. In follow-up of that finding, researchers continued to monitor a subset of cases and measure serial levels of that marker after a diet change. That data has now also been published in a new paper  (Haimovitz et al., 2022).