The baby wombat was pulled from the body of her dead mother last Tuesday. By Sunday she was no longer eating and was showing clear signs of distress.

"She had a distended belly from the beginning but it didn't seem to be causing her any pain," wombat carer Lindy Butcher said.

"By Sunday morning she was clearly in pain and nothing I did was making it better. We took her to the vet and she was put to sleep."

Ms Butcher said after many sleepless nights tending to the baby wombat providing bottle feeds every four hours it was a tough decision, but the right one, to let her go.

"You have to do what is kindest for the little animal. It wasn't treatable and she was in pain," she said.

"The vet did a post mortem for us and verified it was lung injuries and an infection in her intestines. They confirmed there was nothing we could have done which is always reassuring."

Ms Butcher has cared for many wombats and said the first few days after a rescue were critical.

"The first few days are make or break," she said. "We know that. It is sadly not uncommon. It is a sad part of the job, but the nice part of the job is when they grow up big and healthy against the odds and are released."

It is a busy time for wildlife carers and Ms Butcher said the same sad day as Mallee was put down, another baby wombat had been sent to them for care.

"The finders have called him Fitzy," she said. "He is a little bigger, 1.4 kilograms. He was found immediately and is doing very well."