Spare a thought for the vets at London Zoo who have been looking after Lucifer, the 30 stone lion.
The Asian big cat's been given a heath check to make sure he's fit and ready to join a new breeding group for the endangered species in a new location.
Zookeepers had to train the 11-year-old lion, named after his studbook number 666, to lie on his side so they could administer an anesthetic with an injection.
He's part of a special Zoological Society of London campaign, Lion400, aimed at raising £5.7 million to save the species.
Vets gave him an all-over examination in his enclosure down to checking the inside of his mouth to check his teeth.
He's been given a clean bill of health and will move later this week.