Animal-rights organization, Moving Animals, created an online petition calling for Dumbo to be sent to an animal sanctuary, arguing the animal possessed a 'skeletal body' which could have been a sign of 'possible malnourishment and exhaustion'.
The petition received more than 223,000 signatures. But Dumbo was reported to have died shortly after enduring a 'horrible accident' that left him with two broken legs - as he was 'so weak that he collapsed under his own weight'.
Dumbo was taken to the Elephant Hospital in Krabi, where he was admitted on April 17 and passed away at 3 am on April 20.
'Tragic and horrific'
"This is a tragic and horrific end to Dumbo’s heartbreakingly-short life," said Amy, Co-Founder of Moving Animals.
"His skeletal body clearly suggested that he was unwell and could be suffering from malnourishment and exhaustion. And yet the zoo did nothing until receiving international criticism. Under their care, this baby elephant broke both of his back legs, and the zoo did not even realize for three days. I can't bring myself to imagine Dumbo's suffering during this time.
'Outdated animal performances'
Amy also said that Dumbo's death shows how neglected animals kept in captivity are - despite being under the zoo's 'care'.
She added: "We hope that Dumbo is now finding the peace that he was so cruelly denied in his life and that his tragic story will urge Thai authorities to finally put an end to these outdated animal performances."
The Zoo's Manager, Mr. Pichai, told The Phuket News: "Nobody wants to lose something they love. We did the best we could do to protect him."
Phuket zoo are free to 'acquire' another baby if they choose to do so, as authorities rule no laws have been broken.