Abstract

Some calves with neonatal diarrhea and distinctly disturbed general condition have elevated blood levels of D-lactate and respond poorly to the usual correction of acidosis. This observation led to this prospective study with the objective to elucidate whether calves with elevated D-lactate levels require higher doses of sodium bicarbonate and more frequent treatments than calves with normal D-lactate levels. Among the calves admitted to the clinic between September, 2002, and March, 2003, 73 calves with an age of up to 3 weeks were included in this study. Further selection criteria were diarrhea (according to the history or upon admission), and metabolic acidosis with a base excess below -10 mmol/l. Exclusion criteria were hypoglycemia, hyperkalemia, evidence of myodystrophy, severe bronchopneumonia, and navel ill requiring surgical intervention. Within the period of investigation (24 hours) the calves received a standardized therapy but no anti-inflammatory drugs and no oral rehydration solutions. Dosage of sodium bicarbonate was calculated using the formula body weight x base deficit x 0.6 and administered in a volume of 2.5 liters within 3.5 hours. During the subsequent 20 hours the calves received infusions of 0.9 % sodium chloride in volumes corresponding to the estimated fluid loss. Blood samples were taken before the infusion and after four and 24 hours and assayed for D-lactate concentration and base excess; additionally, behavior and posture of the calves were recorded. Voluntary milk intake at the first regular feeding after the end of the investigation was also recorded. Approximately 85 % of the calves had elevated D-lactate levels. Significant correlations between D-lactate levels and both behavior and posture were found, allowing for a relatively reliable diagnosis of hyper-D-lactatemia on the basis of clinical signs. Posture and behavior seemed to be more strongly influenced by D-lactate than by degree of acidosis. No correlations were found between either D-lactate level or base excess, and milk intake. Mean D-lactate concentration decreased very little after the first four hours, whereas a distinct drop was observed after the subsequent 20 hours. A possible explanation for this finding is that metabolism of D-lactate increases after the normalization of blood pH. Significant correlations between D-lactate levels and base excess after the sodium bicarbonate infusion indicate that calves with elevated D-lactate levels have received to little buffer. Furthermore significant correlations between D-lactate levels and base excess after 24 hours indicate that those calves, which still had elevated D-lactate levels after this period of time, in most cases required a repeated treatment with buffer. Conclusion: Calves with clinical evidence of D-lactate acidosis require higher doses of buffer and possibly repeated treatments.