Experimentally induced systemic hyperchloremic acidosis in calves

BACKGROUND: Among the various metabolic disturbances occurring in calves affected by neonatal diarrhea or ruminal acidosis, acidemia constitutes an important condition requiring specific therapy. Although various attempts have been made to estimate the degree of metabolic acidosis on the basis of clinical signs alone, some doubts have been raised regarding the accuracy and predictive value of the clinical parameters suggested. HYPOTHESIS: The induction of metabolic acidosis in healthy calves via the infusion of hydrochloric acid will lead to a clinical picture similar to that seen in neonatal calves with diarrhea or ruminal acidosis. ANIMALS: The study was carried out on 15 Holstein male calves, between 5 and 19 days of age. METHODS: Hyperchloremic metabolic acidosis was induced over a period of 80 minutes by an intravenous infusion of 4000 ml of 0.9% NaCl solution containing 400 mmol HCl. RESULTS: Acidemia occurred rapidly and increased constantly up to a maximum value which was reached in all calves by the end of the administration and amounted to a 22.4 mmol/liter mean base deficit (range from 17.0 to 33.1 mmol/l ). Despite the relatively severe acute acid-base imbalance during the entire observation period, no calves showed any clinical signs; even appetite remained normal. CONCLUSIONS AND CLINICAL IMPORTANCE: The hypothesis was rejected. Factors other than a disturbance of the acid-base balance should be considered to be primarily responsible for the clinical picture in calves affected by diarrhea or ruminal acidosis.