Asiatic lions are extremely rare, and highly vulnerable. Only about 350 remain in the wild, all confined to India’s Gir Forest National Park. This makes the species particularly at risk, and maintaining a healthy reserve population in zoos is vitally important. Every Asiatic lion plays a crucial role in safeguarding the future of the species. At Planckendael ZOO, we do everything we can to protect these endangered big cats. That’s why young Yarzar (born in 2023) recently underwent an extensive medical examination, including both an MRI and a CT scan. This check-up was not only important for his own well-being, but also for the long-term conservation of his species. Recently, Planckendael ZOO was also thrilled to welcome a new lioness to the group.

A Distressing Diagnosis for Sister Yade

The reason for Yarzar’s examination was the diagnosis of his twin sister, Yade. Her keepers had noticed some alarming symptoms: she often stumbled, held her head at an angle and lost her coordination – especially during moments of stress. This persistent behaviour suggested a neurological disorder, affecting the brain or nervous system. To find out what was wrong, Yade was transferred to undergo an MRI and a CT scan at Ghent University.

The resulting images revealed a thickening of her skull that was putting pressure on her brain, explaining her coordination and balance problems. The condition, known as ataxia, also occurs in humans. Sadly, the disease is progressive and incurable. As her condition deteriorated rapidly, the difficult but necessary decision was made to put Yade to sleep.

Checking Up on Yarzar Too

There were two possible causes for Yade’s condition: hereditary factors or a Vitamin A deficiency. Blood tests showed that the diet at Planckendael ZOO contained sufficient Vitamin A, making a hereditary cause more likely. This was also the reason for examining Yade’s twin brother, Yarzar: if the condition is hereditary, he is also at risk.

Yarzar’s scans also revealed a thickening of the skull. However, he is not currently showing any of the symptoms that began to develop in Yade at around nine months of age. The thickening itself is not necessarily a problem, as long as Yarzar behaves normally and shows no signs of ataxia. The Asiatic lion is so critically endangered that each individual animal is vital to the species’ survival.

Because Yarzar is symptom-free and healthy, he has been given the green light to breed as part of the species conservation programme, the European Endangered Species Programme (EEP). In this programme, the mental and physical well-being of the animals involved is always given the highest priority.

Important Insights for the Future

Ataxia is known to affect Asiatic lions in zoos as well as in their natural habitat. The research conducted on Yade and Yarzar is extremely valuable to zoologists, as very little is known about ataxia in Asiatic lions. The brain scans from the animals at Planckendael ZOO are the first ever taken of living lions with this condition. This data will help us better understand the causes and effects of ataxia in this highly endangered species. By sharing these findings with other zoos participating in the EEP, we hope to contribute to the long-term conservation of the Asiatic lion.

By combining the results of this medical research with data from other zoos, we hope to gain a clearer picture of how this disease develops, and how we can better protect the health of these rare lions in the future. This research proves once again that zoo management goes far beyond everyday care and feeding routines: it is an ongoing quest to secure a safe and healthy future not only for individual animals but for the entire species.

Whenever an animal dies in the zoo, an autopsy is standard procedure. A CT scan of Yade and Yarzar’s mother revealed she too had a slight thickening of the skull. These findings show that a lion with such a thickening can still lead a long and fulfilling life.