Hydrallantois in beef cattle: Two case reports

Abstract

In the Buenos Aires Province, a significant number of annual cattle deaths occur for various reasons, with only a small percentage of farms conducting diagnostic confirmations. Among the primary causes of acute death, magnesium deficiency and certain infectious diseases such as bacillary hemoglobinuria and anthrax are noteworthy. Nonetheless, there are secondary factors, such as hydrallantois, which can occasionally be associated with acute death. Hydrallantois refers to the abnormal accumulation of fluid within the allantoic sac. While this condition is more commonly observed in cattle, it remains a rare occurrence in pregnancy. The initial case, which came to the attention of the Veterinary Diagnostic Service at the Faculty of Veterinary Sciences, Universidad Nacional del Centro de la Provincia de Buenos Aires (FCV-UNCPBA) in July 2018, involved a necropsy and diagnostic procedures carried out on an Aberdeen Angus cow from a herd that had witnessed four deaths within a month. The second case emerged in June 2018 when an adult Aberdeen Angus cow was identified through anamnesis and clinical examination by a private veterinarian. Unfortunately, the cow was found dead 18 days after the clinical diagnosis, prompting a post-mortem examination. During necropsy in both cases, a striking finding was the presence of severe hydrallantois in the pregnant uterus, containing more than 100 liters of allantoic fluid. Microscopically, detachment of the fetal trophectoderm was observed with edema and mineralization, evident through an area of connective tissue within the placentomes. This report aims to outline various clinical presentations and highlight the macroscopic and microscopic observations from two cases of hydrallantois in cows. It is vital to emphasize the importance of recognizing this rare pathology as a possible differential diagnosis of acute death in cows, as a consequence of cardiorespiratory failure resulting from thoracic pressure.