Legumes in Dog Diets: Debunking Myths and Exploring Benefits

 

In the past five years, a controversy has brewed in the world of canine nutrition. Dog owners became increasingly concerned about a potential link between legumes in dog food and dilated cardiomyopathy (DCM), a serious but rare heart condition. This concern peaked around 2018-2019, sparking intense debate within the pet food industry and the veterinary community.

Since then, numerous studies have demonstrated the safety of legume-rich diets, leading to a gradual cooling of the initial alarm. Despite this, the controversy hasn't completely subsided. It's worth noting that proving a negative - in this case, definitively showing there is zero relationship between legumes and DCM - is inherently challenging in scientific research.

While no evidence has established a clear link between DCM and legumes alone, some clinical veterinarians still express skepticism about the safety of grain-free dog foods or those that include legumes as a significant protein source. This ongoing debate underscores the complexity of canine nutrition and the importance of continuing research in this field.

In this blog post, we'll delve into the current scientific understanding of legumes in dog diets, examining both the concerns and the potential benefits. We'll explore recent research findings and discuss their implications for dog owners and veterinarians alike. [Note: We have previously explored DCM in this blog post]

The DCM Controversy: Separating Fact from Fiction

Dilated cardiomyopathy (DCM) is a serious but rare heart condition that affects dogs, characterized by an enlarged heart with weakened contractions. Most cases of DCM are genetic and tend to affect large breeds disproportionately. It is also diagnosed more often in male dogs. Diet-related DCM is even more rare and is believed to be a result of a taurine deficiency, as supplementation with taurine or a transition to foods higher in taurine and/or methionine have reversed DCM symptoms in a significant portion of cases. In 2018, the FDA began investigating a potential link between DCM and certain diets, including those containing legumes. However, subsequent research has failed to establish a causal relationship between legumes and DCM.

A comprehensive study published in 2021 in the Journal of Animal Science concluded that "there is no definitive evidence to support removing legumes or pulses from canine diets" [1]. The researchers found that the initial concerns were based on correlational data rather than causation, and that multiple factors, including genetics and overall diet composition, play a role in DCM development.

Health Benefits of Legumes for Dogs

Legumes, when properly incorporated into a balanced diet, can offer several health benefits for dogs:

1. High-Quality Protein: Legumes are an excellent source of plant-based protein, which can be a valuable component of a dog's diet [2].

2. Fiber Content: The fiber in legumes supports digestive health and can help maintain a healthy weight [3].

3. Essential Nutrients: Legumes provide important vitamins and minerals, including folate, potassium, and magnesium [4].

4. Low Glycemic Index: Many legumes have a low glycemic index, which can be beneficial for dogs with diabetes or weight management needs [5].

Research on Legume Safety and Canine Heart Health

Recent scientific studies have provided valuable insights into the safety of legumes in dog diets and their relationship to heart health. Let's review some key findings from prominent research:

1. University of Missouri's Landmark Study: The largest study into DCM to date, conducted by the University of Missouri, involved 65 dogs fed four different diets (both grain-inclusive and grain-free) over a 7-month period. This comprehensive study found no relationship between cardiac biomarkers and diet type, challenging the notion that grain-free or legume-containing diets are linked to heart issues in dogs [6].

2. University of Guelph's Controlled Trial: Researchers at the University of Guelph conducted a randomized, controlled trial with 28 Siberian Huskies, a breed not genetically predisposed to DCM. The study used diets with varying inclusion rates of whole pulse ingredients, including green and yellow peas, pinto beans, chickpeas, and lentils. Importantly, this study found no changes in heart muscle or any cardiac issues associated with these legume-rich diets [7].

3. Nationwide DCM Incidence Study: A collaborative study by the University of Missouri and BSM Partners investigated the incidence rate of DCM cases at veterinary cardiology hospitals across the United States. This research found no correlation between DCM cases and the sales of grain-free foods. Furthermore, the study revealed that there has been no increase in DCM rates over the last 20 years, despite the growing popularity of grain-free and legume-containing diets [8].

4. Taurine Levels and Pulse Ingredients: Additional research published in the Journal of Animal Science (2019) addressed concerns about legumes potentially reducing taurine levels, an amino acid important for heart health. The study found that dogs fed diets containing pulse ingredients maintained normal taurine levels [9].

5. Long-term Safety of Legume-Rich Diets: A study in the Journal of Animal Science (2020) followed dogs fed diets containing 45% legumes for over five years. The research found no adverse effects on heart health or overall well-being, supporting the long-term safety of legume inclusion in canine diets [10].

6. Plant-Based Diets and Heart Health: While vegetarian and meat-free diets were not the focus of the FDA investigation, many of these diets include significant amounts of protein from pulse ingredients and no animal-derived proteins. A groundbreaking study published in PLOS ONE directly tested the impact of a plant-based diet on canine heart health. The research, which included echocardiogram examinations, found that dogs maintained healthy biomarkers on a plant-based diet. Notably, the study observed increases in blood levels of taurine compared to the meat-inclusive control diet, as well as maintenance of healthy heart muscle [11]. This research provides compelling evidence that well-formulated plant-based diets, which often rely heavily on legumes for protein, can support heart health in dogs.

These studies collectively provide strong evidence that legumes, when used as part of a balanced diet - whether alongside animal proteins or as part of a plant-based diet - do not pose inherent risks to canine heart health. The research challenges earlier concerns and suggests that well-formulated diets containing legumes can be safe and nutritious for dogs. For additional research, check out our Research Database. 

Implications for Dog Owners and Veterinarians

The body of research presented here has important implications:

1. Diversity of Options for Omnivores: The studies suggest that a variety of diet types, including those with legumes and plant-based options, can be healthy for dogs when properly formulated.

2. Individual Needs: While the overall evidence supports the safety of legumes in dog diets, it's crucial to remember that every dog is unique. Some may have individual sensitivities or health conditions that require special dietary considerations.

3. Importance of Balanced Nutrition: Regardless of whether a diet includes legumes or is plant-based, the key factor is nutritional balance. Diets should be formulated to meet all of a dog's nutritional needs.

4. Ongoing Monitoring: Regular veterinary check-ups, including cardiac evaluations when appropriate, remain important for maintaining canine health, regardless of diet type.

Conclusion

A prime example of how this research is being applied in practice is our approach at Petaluma, where we focus on developing science-backed, plant-based formulas. In response to the FDA's investigation into grain-free diets and potential DCM risks, we worked with veterinary nutrition experts to formulate our diets in 2018. Our formulation team took into account the known risk factors at that time, incorporating specific supplementation with methionine, taurine, and l-carnitine - nutrients that play crucial roles in heart health.

We have taken a cautious approach to our use of pulse ingredients. Pulse inclusion is limited to approximately 20% of the total formula and less than 30% of the total protein contribution. While chickpeas are listed as the first ingredient on our label due to regulatory requirements, we have opted to source from a broad range of plant-based ingredients rather than relying heavily on one or two. As a result, chickpeas represent less than 15% of our food.

This balanced approach appears to be yielding positive results. We're proud to share that there are reviews on our website from dog owners whose pets were able to reverse signs of diet-related DCM after switching to Petaluma diets. While individual cases should always be evaluated in the context of overall scientific evidence, these reports align with the broader research indicating that well-formulated plant-based diets can support canine heart health.

Our approach at Petaluma exemplifies how companies can responsibly incorporate legumes and other plant-based ingredients into dog food, balancing the nutritional benefits of these ingredients with an abundance of caution regarding potential risks. As our understanding of canine nutrition continues to evolve, such evidence-based, carefully formulated diets provide options for dog owners seeking to make informed choices about their pets' nutrition.

While concerns about legumes and DCM in dogs have been prevalent in recent years, the growing body of scientific evidence supports the safety of legumes in canine diets when used as part of a balanced nutritional plan. As always, dog owners should work closely with veterinary professionals to make the best dietary choices for their individual pets, taking into account the latest research and their dog's specific health needs.

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References:

1. McCauley, S. R., et al. (2021). "Review of canine dilated cardiomyopathy in the wake of diet-associated concerns." Journal of Animal Science, 98(6).
2. Carciofi, A. C., et al. (2008). "A weight loss protocol and owners participation in the treatment of canine obesity." Ciência Rural, 38(1), 266-271.
3. de Godoy, M. R., et al. (2013). "In vitro disappearance characteristics of selected categories of dietary fibers." Journal of Animal Science, 91(6), 2802-2810.
4. Boye, J., et al. (2010). "Pulse proteins: Processing, characterization, functional properties and applications in food and feed." Food Research International, 43(2), 414-431.
5. Adolphe, J. L., et al. (2015). "Health effects of dietary pulse intake in pets." In Pets as Sentinels, Forecasters and Promoters of Human Health (pp. 145-166). Springer, Cham.
6. Bosch, G., et al. (2023). "Meta-analysis examining the impact of dietary pulse ingredients on plasma methionine and taurine concentrations in dogs." Frontiers in Animal Science, 4:1271202. https://doi.org/10.3389/fanim.2023.1271202
7. Adin, D., et al. (2023). "Effect of diet type on blood and plasma taurine concentrations and echocardiograms in dogs – a comparison of grain-inclusive and grain-free dog foods." Journal of Animal Physiology and Animal Nutrition, 107(6), 1273-1281. https://doi.org/10.1111/jpn.13962
8. McCauley, S. R., et al. (2022). "Review of canine dilated cardiomyopathy in the wake of diet-associated concerns." Frontiers in Animal Science, 3:846227. https://doi.org/10.3389/fanim.2022.846227
9. Adin, D., et al. (2019). "Effect of type of diet on blood and plasma taurine concentrations, cardiac biomarkers, and echocardiograms in 4 dog breeds." Journal of Animal Science, 97(4), 1414-1423.
10. Donadelli, R. A., et al. (2020). "Long-term effects of feeding a grain-free diet containing 45% legumes on health parameters in healthy adult dogs." Journal of Animal Science, 98(Supplement_4), 180-181.
11. Dodd, S.A.S., Adolphe, J.L., Verbrugghe, A. (2021). "Plant-based diets for dogs." PLOS ONE 16(6): e0253292. https://doi.org/10.1371/journal.pone.0258044