New Research on Rare Dog Bladder Stones Offers Insight—But Not Alarm

If you're a pet parent who carefully reads labels or researches every supplement before feeding it to your dog, you're already doing something right. But sometimes even the most informed choices can be challenged by new science, especially when unexpected findings surface. 

That’s exactly what happened in a recent study that may have uncovered a possible relationship between an unusual type of bladder stone in dogs and an ingredient commonly found in some pet foods, supplements, and medications: choline bitartrate. 

A Surprising Finding 

From 2020 to 2024, the Minnesota Urolith Center studied more than 318,000 cases of bladder stones in dogs. Out of all those samples, only 63 dogs were found to have a very rare type of stone called calcium tartrate tetrahydrate (CTT). This kind of stone is almost never seen in dogs and has mostly been reported in research animals exposed to tartaric acid, making it an unusual and noteworthy finding in pets. 

The key similarity? Most of these dogs had consumed diets, supplements, or medications containing choline bitartrate, a nutrient source that delivers choline alongside tartaric acid. 

Choline is an essential nutrient that supports liver function, cognition, and metabolism. It’s a required component in many complete-and-balanced dog foods, but in this form, paired with tartaric acid, it may pose risks for some dogs, particularly those predisposed to urinary tract issues. 

Why This Matters 

While 63 out of 318,000 is a small number, the finding has raised important questions about ingredient safety, especially in long-term use. Dogs in the study were primarily small breeds, which typically are at a higher risk for stone formation. Some also had other health conditions, such as kidney or heart disease, further complicating the picture. 

This study is important for several reasons. First, it raises questions about an often-overlooked ingredient, tartaric acid, which has long been used in human foods, medications, and supplements but has not been thoroughly studied in dogs. Second, it serves as a reminder that dogs metabolize substances differently from humans, and ingredients considered safe for people may not be safe for pets. Lastly, it illustrates how even uncommon ingredients can become clinically relevant under the right—or wrong—circumstances, primarily when used repeatedly or in combination with other products. 

Here's What the Study Didn’t Prove 

As valuable as this research is, it represents a very early step in understanding a potentially emerging issue, and it comes with several key limitations that affect how the findings should be interpreted. 

First, the study is observational rather than experimental, meaning it identified a correlation between choline bitartrate (a source of tartaric acid) and the formation of calcium tartrate tetrahydrate (CTT) stones in dogs, but most notably, it did not establish causation. Without a rigorously controlled study, it cannot be said for certain that tartaric acid was the direct cause of the stones. Moreover, this type of study would need to be repeated to confirm findings.  

Second, the diet history collected from participating dogs was incomplete and potentially unreliable. Follow-up surveys were returned for only 33 out of 63 dogs (52%), and the average time between stone removal and survey completion was nearly six months. This introduces the risk of recall bias, where owners or veterinary staff may forget, omit, or misremember what the dog was eating or taking in the months leading up to diagnosis. Since dietary ingredients were central to the hypothesis, gaps or inaccuracies in this information significantly weaken the conclusions. 

Third, the affected dogs shared several overlapping risk factors that complicate the analysis. Most of the dogs were small-breed males, a population already known to be predisposed to calcium oxalate bladder stones, and many had comorbid conditions such as kidney disease. These factors independently increase the risk of stone formation and make it difficult to isolate tartaric acid as the unique or primary trigger. It’s possible that the presence of tartaric acid was incidental or interacted with other conditions or medications, rather than acting alone. 

Finally, a critical shortcoming of this study is the lack of information about the actual dosage and chemical formulation of tartaric acid consumed by participating dogs. The amount of a particular ingredient in commercial foods, supplements, and medications is often proprietary, making it difficult to determine how much a dog has ingested. Without knowing the concentrations involved, we can't assess a safe dosage or define thresholds of concern. 

While the study provides useful insights and raises important questions, it should be viewed as thought-provoking rather than conclusive. It brings awareness to veterinarians, pet food formulators, nutritionists, and pet owners of a potential concern, yet it does not prove that choline bitartrate or tartaric acid definitively causes CTT stones in dogs. Further controlled studies are needed before making broad dietary recommendations or regulatory changes. 

Overall, the incidence of CTT stones remains exceptionally low, and most dogs consuming choline bitartrate experience no adverse effects. However, if your dog has a history of urinary stones or kidney disease, it's worth reviewing their diet and supplements with your veterinarian. 

What Pet Parents Can Take Away 

Stay curious, not fearful. New research can sometimes be unsettling, especially when it suggests that a commonly used ingredient may have unintended consequences. But studies like this are how the pet industry learns, grows, and improves. Rather than sparking panic, they should inspire thoughtful dialogue and scientific progress. 

Learn more about how to decipher pet food research (no PhD required!) in this episode of the Barking Mad podcast! 

It’s also important to remember that more isn’t always better. Supplements can be helpful when used appropriately, but too much of a good thing isn’t always great. Responsible supplementation should be guided by your pet’s specific needs, not trends or assumptions. 

Finally, support brands that take science seriously. Companies that fund feeding trials, publish peer-reviewed research, and are willing to reformulate their products based on emerging evidence are demonstrating a true commitment to pet health. In an evolving industry, that kind of transparency and adaptability is something worth investing in. 

Final Thoughts 

This study reminds us that pet food safety isn’t just about what’s on the label—it’s also about how ingredients behave in the body. While this research offers valuable information, it’s not a cause for widespread alarm. It highlights an emerging area of potential concern that deserves further investigation. There’s much more to learn before we draw firm conclusions about the effects of tartaric acid and choline bitartrate in dogs. 

In the meantime, thoughtful caution, not fear, is the best response. Stay informed, ask questions, and work with your vet to choose the diet that’s best for your dog. Because our pets don’t just need complete and balanced food, they need science-backed nutrition and continuous care. 

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About the Author

Dr. Katy Miller works as the Director of Veterinary Services at BSM Partners. She earned her veterinary degree at Ross University and completed her clinical year at Louisiana State University. She previously served for 11 years as the Director of Dog and Cat Health and Nutrition for Mud Bay where she earned multiple certifications and specialized in pet food nutrition, prior to which she practiced general and emergency medicine for seven years. She is also a competitive three-day eventer, licensed falconer, and claims only two (Golden and Mini Doxie) of their nine dogs.