Traditional and quantitative assessment of acid-base and shock variables in horses with atypical myopathy.
Authors: van Galen G, Cerri S, Porter S, Saegerman C, Lefere L, Roscher K, Marr C, Amory H, Votion D M
Journal: Journal of veterinary internal medicine
Summary
Atypical myopathy (AM) in horses presents with poorly characterised acid-base disturbances that may complicate clinical assessment and treatment decisions. Van Galen and colleagues examined venous blood gases, electrolytes and shock variables in 34 AM-affected horses versus 15 healthy controls, employing both traditional acid-base interpretation and the quantitative strong ion model to identify specific derangements. Most AM cases exhibited tachycardia, tachypnea, elevated or normal packed cell volume and blood urea nitrogen on admission, with acid-base abnormalities predominantly featuring respiratory alkalosis, lactic acidosis and strong ion difference alkalosis occurring singly or in combination. Quantitative analysis using the strong ion model distinguished these mixed derangements more accurately than conventional approaches, with nearly all measured variables except pH, potassium concentration and total protein differing significantly between affected and control horses (P <0.001). Practitioners should routinely evaluate acid-base status in suspected AM cases using the strong ion model rather than traditional interpretation, as this approach provides more precise identification of the underlying pathophysiological mechanisms and may better guide fluid therapy and supportive care decisions.
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Practical Takeaways
- •When evaluating horses with suspected atypical myopathy, assess acid-base status using strong ion difference model rather than traditional methods for more accurate diagnosis of mixed acid-base disorders
- •Monitor for signs of shock (tachycardia, tachypnea, elevated PCV/BUN) in atypical myopathy cases as these are common on presentation and may guide treatment intensity
- •Lactic acidosis combined with respiratory alkalosis is a characteristic finding in AM and should prompt investigation for this condition when seen together
Key Findings
- •Horses with atypical myopathy presented with tachycardia, tachypnea, and normal to elevated PCV and BUN on admission
- •Acid-base abnormalities were predominantly respiratory alkalosis, lactic acidosis, and strong ion difference alkalosis, alone or in combination
- •Nearly all evaluated variables except pH, potassium, and total protein differed significantly between AM cases and controls (P < 0.001)
- •Strong ion model provided more accurate assessment of acid-base derangements than traditional approach, identifying mixed derangements missed by conventional analysis