Physiological alterations and predictors of death in neonatal calves with weak calf syndrome

Background: Weak calf syndrome (WCS) is characterised by weakness, poor vitality and difficulty standing or suckling. Early identification of physiological alterations and prognostic indicators is critical for improving the management and survival of weak calves. Methods: Twenty-six neonatal calves, aged 1–5 days, that were unable to stand or suckle were analysed for electrolytes, blood gases, serum biochemistry and protein electrophoresis. The prognostic utility of these variables was then evaluated using receiver operating characteristic analysis. Results: Twenty calves survived, while six died—four on the first day, one on the fourth day and one on the seventh day. Surviving calves lived for at least 90 days. Hypothermia occurred in 16 calves, elevated pCO₂ in 23 calves, acidaemia in 17 calves and hypoproteinaemia in all calves. Calves that did not survive had lower pH and alkaline phosphatase (ALP) than those that survived, while their pCO₂ and L-lactate were higher. pCO₂ showed excellent performance as a prognostic indicator, while pH and ALP showed good prognostic performance. Limitations: The small population size, absence of a control group and non-standarsdised timing of diagnosis limit the generalisability of the findings. Furthermore, postmortem investigations were not conducted, so the causes of death could not be definitively identified. Conclusion: Weak calves exhibit hypothermia, respiratory acidosis, hyperlactataemia and passive immunity failure. Parameters such as pH, pCO₂ and ALP are important prognostic indicators in these calves.