The pup, which was born on Tuesday and euthanased on Wednesday, was found to have had 10% of normal lung capacity.
Niwa cetacean biologist and leopard seal specialist Dr Krista Hupman said the results showed the pup’s lungs were filled with fluid and hardly working.
"Unfortunately, this meant if the seal hadn’t been euthanased it would have endured a slow and painful death.
"It was a huge relief for everyone involved to know that the decision to put the pup down was the kindest option."
Dr Hupman travelled to Dunedin from Auckland with two students as soon as she found out the pup had been born.
It was the first birth of leopard seal to be witnessed and the second known leopard seal birth in New Zealand in the past 40 years.
Dr Hupman arranged the scans at Pacific Radiology in Dunedin in conjunction with the Department of Conservation and Otago Museum staff after the pup was euthanased.
"We know an MRI has never been conducted on any seal before, so this is an incredible opportunity for us to learn more."
The birth and death of the pup had motivated the formulation of a group involving Niwa experts, volunteers and Otago Museum staff so more research on the species could be carried out, Dr Hupman said.
"We are hoping to conduct a necropsy, or animal autopsy, on this pup and work together on publishing some of our findings from the CT and MRI scans.
"We hope the necropsy will help us learn more about this species that currently we know extremely little about."
