Haemolytic disease in new born calves

Area of Science:

• Veterinary Pathology
• Immunology
• Animal Reproduction

Background:

• Neonatal haemolytic disease poses a significant threat to beef herds.
• Babesiosis is a prevalent tick-borne disease affecting cattle.
• Vaccination protocols aim to prevent babesiosis but can have unintended consequences.

Purpose of the Study:

• To investigate the cause of neonatal haemolytic disease in a Bos indicus crossbred beef herd.
• To determine the role of Babesia argentina vaccination in the observed pathology.
• To elucidate the pathophysiological mechanism leading to neonatal mortality.

Main Methods:

• Clinical case investigation in a beef herd in south-east Queensland.
• Autopsy, histopathological, and haematological examinations of affected calves.
• Analysis of vaccination history and antibody persistence in dams.

Main Results:

• Diagnosis of neonatal haemolytic disease strongly associated with B. argentina vaccination during early pregnancy (non-pregnant or <1 month pregnant).
• Evidence of persistent antibody levels in dams following multiple vaccinations (5-6 doses).
• Pathological findings in deceased calves (within 24 hours of birth) consistent with disseminated intravascular coagulation (DIC), including pulmonary capillary fibrin deposition and severe pulmonary edema.

Conclusions:

• Babesia argentina vaccination of pregnant cattle, particularly in early gestation, can induce neonatal haemolytic disease.
• The mechanism involves maternal antibody transfer leading to DIC and subsequent fetal/neonatal complications.
• Vaccination timing and antibody persistence are critical factors in preventing adverse outcomes in calves.