The newborn elephant calf separated from its herd and then rescued from a jungle stream in Kanchanaburi last week died early Tuesday morning.
The Department of National Parks, Wildlife and Plant Conservation said the calf, a week-old female, died in her sleep at Sai Yok National Park headquarters about 2am.
The calf had been drinking milk every few hours and veterinarians gave it intravenous hydration and oxygen. It appeared exhausted, trying unsuccessfully to stand up, and had continued to suffer from diarrhoea.
Veterinarians said it was probable the young jumbo died of acute renal failure, based on a blood test. She had also possibly suffered internal organ disorder since birth.
The calf was first sighted on Tuesday last week and rescued in Sai Yok National Park on Thursday. The site was remote, with access only by boat, a trip which took a few hours.
Park officials believe the calf had been separated from its herd for a few days. It was exhausted when rescued, was severely dehydrated and had sores in and around its mouth and navel.
On Monday, vets said it appeared to be recovering, only for the calf to die on Tuesday morning.