WATCH | Thor the lion has vasectomy after siring five cubs in a year

A lion had a vasectomy on Thursday after his Dutch keepers decided he had sired enough cubs.

Thor, 11-years-old, had fathered five cubs with two lionesses in the past year, staff at Burgers' Zoo in Arnhem said.

Veterinarian Henk Luten said it was the first time in his 35-year career at the zoo that he had carried out the procedure on a lion.

“Why are we doing it? Because he's a proven breeder. We have a lot of offspring and we don't want to have him overpopulating the genetic pool,” Luten said.

Staff said they had chosen to carry out a vasectomy not a castration which could have caused Thor to lose his mane, along with his standing in the pride's social hierarchy.

Five staff had to lift the heavy sedated lion onto the operating table in the zoo's clinic.