Study links metabolic acidosis to worse outcomes in hyperlactatemic dogs

A large retrospective study of 3,866 dogs with hyperlactatemia is adding nuance to a familiar emergency-room biomarker: lactate. Published in the Journal of Veterinary Emergency and Critical Care, the study found that metabolic acidosis occurred in 37.5% of these dogs and was associated with significantly increased mortality compared with dogs that had hyperlactatemia without metabolic acidosis. The authors, Laurence M. Saint-Pierre, Steven E. Epstein, and Kate Hopper, evaluated cases using both traditional and semiquantitative acid-base frameworks. (onlinelibrary.wiley.com)

That question matters because hyperlactatemia is common in veterinary emergency and critical care, but it doesn’t always reflect the same physiology. Earlier literature has shown lactate can be elevated without overt lactic acidosis, depending on the balance of concurrent acidifying and alkalinizing processes. Reference material used in clinical pathology notes that hyperlactatemia can occur without a fall in pH or bicarbonate, while prior emergency-room studies in dogs and cats found plasma lactate correlated poorly with anion gap and that semiquantitative analysis often uncovered abnormalities that traditional calculations missed. (eclinpath.com)

The new paper also fits into a longer line of work from this research group. In a 2021 retrospective study of 4,863 canine and feline emergency cases, Saint-Pierre, Hopper, and Epstein reported that hyperlactatemia was associated with increased mortality in several canine disease categories, including shock, respiratory disease, diabetes mellitus, and liver dysfunction. An earlier 2018 study similarly compared the prognostic utility of lactate, pH, base deficit, and anion gap in emergency patients, reinforcing that lactate’s meaning depends on the broader acid-base context rather than a single number in isolation. (pubmed.ncbi.nlm.nih.gov)

The broader acid-base literature helps explain why. In a 2012 study led by Hopper, metabolic acidosis was identified as a common abnormality in dogs and cats, and hyperlactatemia was a frequent contributor in dogs. In a 2014 prospective emergency-room study, semiquantitative analysis identified increased unmeasured anions in 68 of 98 cases, compared with 34 cases detected by anion gap alone, suggesting that traditional analysis can underrecognize clinically relevant disturbances. More recent disease-specific work in dogs with GDV reached a similar conclusion: traditional acid-base analysis was frequently normal even when semiquantitative analysis showed multiple concurrent abnormalities, including hyperlactatemia, unmeasured anions, hyperchloremia, hypoalbuminemia, and contraction alkalosis. (onlinelibrary.wiley.com)

Direct outside commentary on this specific paper was limited in the available literature and search results. Still, the surrounding expert literature points in the same direction. Reviews and clinical references by Hopper and others emphasize that metabolic acidosis in critically ill small animals is often mixed in origin and that treatment should focus on the underlying cause rather than reflexive correction of numbers alone. Recent fluid-therapy studies in dogs also underscore that the acid-base picture can shift with resuscitation choices, particularly when chloride load, balanced crystalloids, and lactate-containing solutions are involved. (sciencedirect.com)

Why it matters: For veterinary teams, this study is less about proving lactate is useful, and more about showing that lactate needs context. A dog with hyperlactatemia may have concurrent metabolic acidosis, compensatory respiratory changes, unmeasured anions, hyperchloremia, or offsetting alkalotic processes that make the traditional profile look less dramatic than the underlying physiology really is. If concurrent metabolic acidosis marks a higher-mortality subgroup, that could support more careful interpretation of blood gas, electrolytes, albumin, and chloride in triage and ongoing monitoring, especially in shock, sepsis, GDV, diabetic crises, and other unstable patients. (onlinelibrary.wiley.com)

It may also have practical implications for how clinicians think about bedside analytics. The 2014 comparison study concluded that physicochemical approaches identified more animals with unmeasured anions than the traditional anion gap calculation, but it also noted that more work was needed to determine whether that extra complexity improves management enough to justify the added effort and cost. This new 3,866-case analysis strengthens the case that the distinction is clinically meaningful, at least prognostically, in dogs with hyperlactatemia. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next step is prospective validation, particularly studies asking whether semiquantitative acid-base analysis changes treatment decisions, fluid strategy, or outcomes, and whether it can be translated into simpler protocols for general practice and ER settings. (pubmed.ncbi.nlm.nih.gov)