Physicochemical interpretation of acid-base abnormalities in 54 adult horses with acute severe colitis and diarrhea.
Authors: Gomez D E, Arroyo L G, Stämpfli H R, Cruz L E, Oliver O J
Journal: Journal of veterinary internal medicine
Summary
# Acute Severe Colitis and Acid-Base Derangements: A Physicochemical Perspective Acute severe colitis in horses triggers profound electrolyte losses and acid-base disturbances that traditional venous blood gas analysis alone may not fully explain; this study applied physicochemical interpretation—examining strong electrolytes (sodium, potassium, chloride), carbon dioxide tension, and plasma protein concentration—to understand the underlying mechanisms in 54 adult horses presenting with acute diarrhoea. The authors calculated both conventional anion gap and the more sophisticated strong ion gap to identify unmeasured anions and distinguish between different types of acid-base abnormality, providing a granular assessment of what drives pH and bicarbonate changes beyond simple hyperchloraemic acidosis. By integrating electrolyte quantification with blood gas parameters, the research clarifies which pathophysiological mechanisms predominate in severe colitis cases—whether hypochloraemia, hypokalaemia, hypoproteinaemia, or unmeasured anion accumulation—each of which demands different therapeutic prioritisation. For practitioners managing these emergencies, understanding the physicochemical basis of acid-base derangement allows more targeted fluid therapy and electrolyte replacement rather than empirical treatment; recognising whether a horse's acidosis stems primarily from chloride depletion, weak acid changes, or accumulating unmeasured anions fundamentally alters clinical decision-making and prognostic assessment in severe colitis cases.
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Practical Takeaways
- •Use strong ion gap (SIG) analysis in addition to traditional anion gap (AG) assessment when managing horses with acute colitis to better understand acid-base disturbances and guide fluid therapy
- •Monitor plasma electrolytes, protein concentration, and pCO2 concurrently as all three factors directly influence acid-base status and treatment decisions
- •The physicochemical approach provides more detailed interpretation of acid-base abnormalities than traditional methods, potentially improving management of severely colitic horses
Key Findings
- •Physicochemical approach using strong ion gap (SIG) and anion gap (AG) effectively identifies unmeasured anions in horses with acute colitis
- •Strong electrolytes, pCO2, and plasma protein concentration are quantitatively determinant of plasma pH and bicarbonate in acute equine colitis
- •Study demonstrates application of Stewart's physicochemical acid-base interpretation in 54 adult horses with gastrointestinal disease