Association of electrolyte concentrations with pH of blood and urine of cows with left-sided abomasal displacement.

BACKGROUND: Ruminants with left-sided abomasal displacement (LDA) often develop metabolic alkalosis and paradoxical aciduria. HYPOTHESIS/OBJECTIVES: To descriptively characterize electrolytes and acid-base variables in cows with LDA compared to healthy cows using the physicochemical (Stewart) approach, and to exploratively assess the influence of blood and urinary electrolytes on pH. ANIMALS: Twenty healthy dairy cows and 20 cows with LDA. METHODS: Retrospective cross-sectional study. Electrolytes, pH, total protein (TP), β-hydroxybutyrate (BHB), and glucose were measured in venous blood and urine. Base excess, anion gap, strong ion difference (SID), and strong ion gap (SIG) were calculated. Associations were evaluated using 2 stepwise forward multiple linear regression models. RESULTS: Cows with LDA had significantly lower venous concentrations of sodium, chloride, potassium, magnesium, and calcium (P = .0013, P = .0023, P < .001, P < .001, P < .001), higher BHB (P < .001), and higher blood pH (P = .003) compared to controls. Calculated SID3, SID4, SID5, and SIG did not differ significantly between groups (P = .2, P = .37, P = .40, P = .62). In urine, cows with LDA showed significantly lower concentrations of Na+, K+, Cl-, Mg2+, and HCO₃- (P = .0007, P < .001, P < .001, P = .004, P < .001). Urinary SID3 and SID5 were also significantly lower (both P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Acid-base disturbances in cows with LDA can be interpreted using the physicochemical approach. Alterations in electrolyte concentrations contribute to changes in pH.