In 368 cows with various abomasal disorders - left abomasal displacement (LAD), right abomasal displacement (RAD), abomasal volvulus (AV) and abomasal impaction (vagal indigestion) - the degree of dehydration was compared with electrolytes and acid-base status of the cows. No clinical symptom of dehydration was observed in 62% of cases with LAD and 43% of cases with RAD. The cows were moderately and severely dehydrated in 86% of the cases with AV and 84% with abomasal impaction. Hypochloremic alkalosis was observed in cows with LAD only when the cows were severely dehydrated, but cows with RAD revealed less electrolytes and acid-base abnormalities despite the increase in the dehydration score. In cows with AV, the acid-base status could not be predicted by the degree of dehydration. Profound hypokalemia and hypochloremia were observed in cows with abomasal impaction for all dehydration states. These findings indicated that hypochloremic alkalosis could be predicted in cows with abomasal impaction for all dehydration states and in LAD cases with marked dehydration, but not in RAD cases.