Could a simple Tums tablet help dogs after grape ingestion?

Why we’re still talking about grapes

As veterinarians, we’ve all had that call: “My dog just ate a few grapes. Should I be worried?” And despite years of clinical experience and a growing body of literature, the answer remains frustratingly complex. Grape and raisin toxicity in dogs continues to be one of veterinary medicine’s most enigmatic and alarming toxicities. Some dogs can eat a handful with no apparent ill effects. Others spiral into acute kidney injury after a single raisin. Despite this unknown, treatment protocols are aggressive and plan for the “worst case scenario.”

At a recent journal club discussion, a group of IndeVets veterinarians tackled a new and thought-provoking angle on this issue: Could administering oral calcium carbonate (Tums) immediately after ingestion mitigate the renal damage caused by grapes or raisins by way of reducing bioavailability of the toxin (tartaric acid)? The short answer: maybe. But the real value of this discussion lies in the nuance, clinical judgment, and curiosity it sparked – all things our profession needs more of.

The journal club discussion centered on the peer-reviewed article published in JAVMA (2025)1: “Tartaric acid as a candidate nephrotoxin in dogs with grape or raisin toxicosis.” This JAVMA Viewpoint article proposes tartaric acid as the likely toxic agent in grapes and raisins and explores whether oral calcium carbonate could theoretically limit absorption.

Let’s dive into the key takeaways from this lively vet-to-vet conversation, and why it matters for everyday clinical practice.

The hypothesis: why calcium carbonate might help

The hypothesis discussed stems from emerging research that identifies tartaric acid as the potential culprit behind grape and raisin toxicity. The theory is that calcium carbonate, when administered orally, binds tartaric acid in the GI tract, forming calcium tartrate, a less bioavailable compound. In neutral pH conditions, this binding could theoretically reduce tartaric acid absorption and, by extension, lessen renal damage.

While the concept is rooted in chemistry and stoichiometry, and seems biologically plausible, it’s important to note that this theory is not yet supported by prospective clinical studies. As one IndeVet put it, “The math checks out, but we’re still flying blind when it comes to real-world outcomes.” Realistically, given the wide variation in clinical response to grape or raisin ingestion, prospective studies are difficult to design.

The clinical debate: would this change your treatment plan?

Here’s where the IndeVets journal club conversation got especially real. Would this new theory change anyone’s actual treatment plan in the ER or clinic?

“It’s not gonna change the way I handle grape and raisin toxicity,” one vet stated bluntly. “But I might tell owners to give Tums on the way in.”

That seems to be the consensus: Calcium carbonate is safe, accessible, and unlikely to cause harm in an otherwise healthy dog. As such, it may offer a small window of action while the owner is en route to the clinic – particularly in rural settings or when immediate transport isn’t possible.

This simple recommendation – “Give Tums and come in ASAP” – might help owners feel like they’re doing something useful, without delaying essential decontamination efforts such as emesis induction, activated charcoal, IV fluids, and lab monitoring. In a perfect world, the administration of calcium carbonate at home might make all the difference in the overall outcome of the case.

Key clinical takeaways:

1. Oral calcium carbonate (Tums) may theoretically reduce tartaric acid absorption by forming calcium tartrate, which is less bioavailable.
2. There is no clinical or prospective data yet showing that this reduces renal injury in dogs.
3. The administration of Tums (at 70-185mg/kg/d) should not replace or delay standard treatment protocols (emesis, IV fluids, lab work).
4. For dogs exposed to grapes/raisins, it’s reasonable to recommend Tums during transport to the clinic, especially if it’s going to take some time to get there.
5. Consider including serum calcium levels in your baseline diagnostics if this approach is used, especially for dogs with potential underlying metabolic or renal concerns.

Why we can’t say “yes” or “no” (yet).

The discussion also shed light on a frustrating but common refrain in veterinary medicine: the lack of large, controlled studies. In this case, the variability in individual susceptibility makes grape toxicity especially difficult to study. Some dogs appear completely unaffected after large ingestions, while others suffer acute renal failure after minimal exposure.

As one IndeVet put it: “It’s hard to study something when you don’t even know if it’s going to cause a problem in the first place.”

And yet, this very uncertainty is what makes this new idea so compelling. It opens the door for future retrospective studies, case series, and, with time, perhaps more robust data collection on cases where Tums was used as a pre-hospital intervention.

Other perspectives on this topic

In addition to the article discussed in the journal club, other veterinary professionals and researchers have offered perspectives on this emerging topic:

• A PubMed study from early 2024 also explores the molecular mechanism and pharmacodynamics of tartaric acid toxicity, reinforcing the potential for calcium interaction PubMed study.
• On the clinical communication side, social media discussions led by veterinarians like Dr. Adam Christman have helped spark more widespread awareness of this potential intervention (Facebook video).

Should you add this to your protocol?

At this stage, not officially. But it’s a conversation worth having with your team – especially your CSRs and triage techs who take panicked calls from pet owners. Adding a simple line to your grape/raisin protocol like:

“If safe to do so and the dog is otherwise healthy, have the owner give a Tums (calcium carbonate; commercially available as 500–750mg tablets) and bring the pet in immediately for evaluation.”

It could be a low-risk, potentially high-reward action.

Why this matters for you, the veterinarian

It’s easy to feel whiplash from constantly shifting recommendations, especially when they’re based on limited data. But the journal club conversation here is a powerful reminder of why clinical curiosity matters. It’s about more than protocols – it’s about being a part of a community that thinks deeply, questions boldly, and shares generously.

And that’s exactly the kind of environment IndeVets fosters. When you’re empowered with the time to read, collaborate, and dig deeper, you’re better equipped to offer the kind of medicine your patients deserve.

Final thoughts: a Tums tablet and a whole lot of thought

No, Tums aren’t a magic cure for grape toxicity. But they may be one more tool in our evolving veterinary toolbox – one that’s safe, accessible, and easy to implement.

And perhaps more importantly, this conversation represents what’s best about our profession when it’s working as it should: vets sharing ideas, questioning assumptions, and striving for better, together.

Interested in more practical, case-driven insights like this?

Sign up for our next clinical webinar or explore how joining IndeVets can help you practice medicine on your terms with clinical excellence and curiosity at the forefront.

Because great medicine doesn’t happen alone.

Citations: 

1. Tancredi W, Bolduc S. Could oral calcium carbonate mitigate tartaric acid toxicity in dogs? A novel hypothesis. J Am Vet Med Assoc. 2025 Aug 20:1-2. doi: 10.2460/javma.25.03.0160. Epub ahead of print. PMID: 40840530.