Samut Prakan Livestock Development Office inspected the area’s zoo and crocodile farm after photos on social media showed a thin elephant performing.
Visitors also criticised the crocodile farm’s care.
Manager Uthen Yangprapakorn insisted all the animals there were fed well.
Uthen told reporters that his horses were 15 years old and some crocodiles lived to 80.
"If we hadn't taken care of them well, they wouldn't live this long," he said.
Uthen said the farm had conducted annual health checks on all its five elephants on December 4.
He said the elephant was on a diet to prevent it from becoming fat. Elephants with high body fat were more prone to being in the mating season and often become more aggressive, Uthen said.