Neonatal beef calf morbidity and mortality in Missouri

Abstract

Neonatal morbidity and mortality are major causes of economic loss for US beef cattle producers. The Missouri cattle industry represents 19 percent of the total agriculture sales in the state and is valued at 1.6 billion dollars. It is estimated that calf sales can account for up to 55 percent of a farm's gross cash income which highlights the economic importance of calf health to producers. The overarching aim of this body of work was to characterize morbidity and mortality of neonatal beef calves with a focus on bacteremia. An additional goal was to determine if any prognostic factors could be identified that may indicate a calf is likely to survive a critical illness. This body of work is comprised of two studies, one retrospective study on necropsy findings in neonatal beef calves presented to the University of Missouri's Veterinary Medical Diagnostic Laboratory and one prospective study conducted on critically ill neonatal beef calves presented to the University of Missouri's Food Animal Clinic. The objective of the retrospective study was to describe lesions and abnormal test results among neonatal beef calves presented to a veterinary diagnostic laboratory. Overall, 1,060 reports were reviewed and inclusion criteria were bovine, 2 to 21 days of age, and of a non-dairy breed. Statistical analysis was performed to compare age, system affected, and pathologic agent types in addition to interactions between each system affected. A total of 95 cases met the inclusion criteria. Median age of enrolled calves was 9 days (range: 2 to 21). A total of 252 lesions were identified with a median of 3 lesions/calf (range: 0 to 7) and 2 different body systems involved/calf (range, 0 to 5). The most common disorders were classified as digestive (42.1 percent [106/252]), respiratory (12.7 percent [32/252]), and multisystemic (11.1 percent [28/252]). With respect to age and system affected, calves with neurologic lesions were significantly younger (mean age: 5.1 days) than calves with digestive lesions (mean age: 9.6 days). For the prospective study, the study objectives were to determine the prevalence of bacteremia in neonatal beef calves, identify factors predictive of bacteremia, and identify factors associated with survival. A total of 27 calves were enrolled in the study. Median age of calves was 7 days (range, 1 to 21). Diarrhea was the most common presenting complaint and was present in 26 percent (13/50) of calves. Most calf deaths occurred either during hospitalization or by 2 weeks after discharge. A lower prevalence of bacteremia (17 percent) was found in this study compared to previous reports. In this study, no bacteremic calves survived. Hypothermia, hypercapnia, and hyperfibrinogenemia were associated with decrease likelihood of survival. The results of this thesis suggest that calves submitted to a veterinary diagnostic laboratory have a high prevalence of infectious diseases, mainly digestive, respiratory and multisystemic in origin. In addition, critically ill calves are more likely to die during hospitalization or in the first 2 weeks after discharge and that hypothermia, hypercapnia, and hyperfibrinogenemia were associated with decreased likelihood of survival. These findings could help guide producers and veterinarians when assessing factors contributing to neonatal beef calf loss and establishing prognosis for critically ill calves.