Stillbirth Caused by Vitamin A Deficiency in Captive African Lion Cubs (Panthera leo)

This study investigates the pathology of two stillborn lion cubs presented to the Laboratory of Pathology by analysing their necropsy findings and concluding with possible diagnoses.

At first, a systematic necropsy was performed, and then, the samples of various tissues were collected and divided into three parts for bacterial culture, histopathology studies and molecular analysis. The conventional polymerase chain reaction (PCR) was conducted to detect common foetal infectious agents associated with stillbirth in carnivores, such as canine adenovirus-2, canine distemper virus, canine parainfluenza virus, canine parvovirus and Toxoplasma gondii. In the case of the liver, an additional sample was taken for vitamin A analysis.

As reported in history, the lions were kept in a small zoo, where they were fed the same amount of chicken and red meat. At necropsy, it was observed that both cubs had haemoperitoneum and haemothorax. Moreover, diffuse congestion and focal haemorrhage were observed in the lung, heart, liver, kidney, spleen and tight muscles. Notably, extensive haemorrhage was observed in the adrenal gland. The marked thickening of the cranial (skull) bones associated with the brain compressing and marked vascular congestion was found. At PCR, no infectious agent was found. At microscopic examinations, the tracheal epithelium showed squamous metaplasia along with focal and mild vascular congestion. Additionally, the desquamation of epithelium was observed in the stomach and intestine along with mild focal congestion. Notably, severe and extensive haemorrhage and necrosis were found in the other examined tissues. The liver vitamin A levels in both stillborn cubs were significantly low, at 85.7 and 23.3 µg/g of tissue, respectively.

Our findings supported a diagnosis of vitamin A deficiency when compared with the normal reference value reported in another previous study on wet liver samples obtained from a wild lion. It is suspected to be the cause of stillbirths, neonatal deaths and multiple anomalies in lion cubs.