Melbourne's playful elephant calf Willow has succumbed to a deadly blood infection just seven weeks after she was born in the city's zoo.
Melbourne Zoo head vet Michael Lynch made the decision to euthanise the baby calf on Monday after a scan revealed the life-threatening infection had worsened.
"We took her for some specialised scanning down at Melbourne University vet school and that demonstrated quite clearly to us the damage to her joint, on her hind leg, was so severe that she would not have a normal life afterwards," Dr Lynch told AAP on Tuesday.
Willow was taken back to the zoo to be with her mother Num-oi before being euthanised on Monday evening.
Willow had shown signs of improvement after being born with carpal flexure which made it difficult for her to stand and suckle.
But a fortnight ago she contracted the staphylococcus infection, which spread over time.
Elephant manager Dominic Moss described Willow as tenacious and vocal.
"If you were late giving her food, she would trumpet and carry on," Mr Moss told AAP.
"The mind was there but the body just wasn't able."
Animal rights group PETA has called for the closure of the zoo's elephant exhibit saying it lacks space and stimulation.
"This is the second of Num-Oi's babies she has watched die," spokeswoman Laura Weyman-Jones said on Tuesday.
Num-Oi's only other calf, Sanook, died before his first birthday after a freak accident in 2013 with a favourite toy.
Melbourne Zoo's Judith Henke says, however, noted that deforestation has led to the destruction of elephants natural habitat in places such as Asia.