Study highlights hidden sodium load in ICU-hospitalized dogs

A new prospective observational study is putting numbers to a source of sodium ICU teams often know is there, but may not fully quantify: fluid creep. In 29 dogs hospitalized in an ICU, investigators found that fluid given as medication carriers, diluents, and IV flushes represented a small but constant contribution to sodium administration, even as total fluid volumes decreased over the course of hospitalization. The paper, by Abigail E. McNally and Efa Llewellyn, was published in the Journal of Veterinary Emergency and Critical Care. (eurekamag.com)

The finding lands in the middle of a broader rethinking of fluid therapy in veterinary medicine. Over the last several years, veterinary critical care literature has moved toward the idea of “fluid stewardship,” recognizing that fluids are not benign background therapy but active treatments with dose-dependent risks. Reviews on fluid overload in small animals have specifically highlighted the possibility that maintenance fluids and fluid creep can make up a substantial share of administered water and sodium, borrowing from a concept that has been studied more extensively in human ICUs. (frontiersin.org)

What this study appears to add is prospective canine ICU data focused specifically on sodium burden, not just total volume. According to the study summary, the investigators measured both fluid volume and sodium administration in hospitalized dogs and found that fluid creep remained present even after overall fluid delivery fell. That distinction is clinically useful: a patient may look as though it has been “de-escalated” from a fluid standpoint, while still receiving ongoing sodium through multiple small inputs spread across routine ICU care. (eurekamag.com)

That concern is consistent with current veterinary guidance. The 2024 AAHA Fluid Therapy Guidelines for Dogs and Cats emphasize individualized fluid prescriptions, active reassessment, and vigilance for both fluid excess and electrolyte disturbances. Other veterinary references note that commonly used replacement crystalloids contain sodium concentrations near plasma and can contribute to excessive sodium exposure when used longer term or in patients with altered water balance. Merck’s veterinary guidance similarly cautions that prolonged use of sodium-rich replacement fluids can become problematic in some patients. (pubmed.ncbi.nlm.nih.gov)

Direct outside reaction to this specific paper was limited in publicly indexed sources, but the larger industry conversation points in the same direction. Veterinary educators and criticalists discussing fluid stewardship have increasingly focused on “hidden fluids,” sodium load, and the need to distinguish replacement, maintenance, and incidental administration. That aligns with the study’s practical message: the sodium patients receive is not limited to the bag hanging on the pump. (podscan.fm)

Why it matters: For veterinary professionals, this is less about a dramatic change in practice than about better accounting. ICU teams already monitor rates, body weight, urine output, perfusion parameters, and serial electrolytes, but this paper suggests sodium tracking may need to be more granular in some patients. Dogs with kidney injury, impaired free-water handling, hypernatremia risk, or developing fluid overload may be especially vulnerable to the cumulative effect of flushes, CRIs, and medication diluents that seem trivial one by one. It also reinforces the role of technicians and nurses, whose line-by-line documentation often determines whether these hidden inputs are visible enough to change the plan. (pubmed.ncbi.nlm.nih.gov)

The study also underscores a gap in the evidence base. Veterinary fluid therapy still relies on a relatively limited number of prospective clinical studies compared with human medicine, something the AAHA guidelines acknowledge directly. If future work links fluid creep-associated sodium exposure with outcomes such as dysnatremia, length of stay, or fluid overload, it could push hospitals toward more formal sodium audits, lower-sodium maintenance strategies in selected patients, or tighter standardization of flush and dilution protocols. That’s an inference based on the direction of current guidance and adjacent literature, rather than a conclusion this study itself has proven. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next step will be whether follow-up studies move from description to intervention, testing whether reducing fluid creep changes electrolyte trends, fluid balance, or clinical outcomes in ICU dogs, and whether similar patterns are seen in cats and other high-risk hospitalized patients. (frontiersin.org)