Zoo authorities blamed the death on a sedating attempt that went wrong when Goyana was at the San Diego zoo in the US, from which they obtained the animal through an exchange programme. It was brought to Delhi zoo this April.

Dr N Paneer Selvam, a vet at Delhi zoo, said the needle broke off from a drug-loaded dart San Diego zoo staff used on the rhino and lodged itself in a soft region of the neck. Vets there tried to remove it but failed.

Because of muscle movements, the needle made its way from the neck to the abdomen and caused infection in the anterior two of the rhino's four stomach bags, said Dr Selvam. He said that moving about in the stomach bags the needle pierced the heart and this led to pericarditis, or infection of the membrane surrounding the heart, from which the rhino died.

During postmortem two litres of pus and another three litres of fluids were found in the stomach bags, indicating the extent of the infection. The heart showed punctures that could have come from the needle. But the needle hasn’t been found.

“The San Diego zoo’s 20-page medical report given to us while handing over the rhino had only one line saying that a needle had broken off during a sedating attempt and could not be removed,” said Dr Selvam.

Experts at the zoo said that even if the report had had more details, it would have been difficult to locate and retrieve the needle because rhino hide impedes X-rays. “When Goyana was brought here by the San Diego zoo staff, she had some facial and hind leg injuries from transport. So we assumed that was why she was ill,” zoo director D N Singh said. “The injuries healed, but the rhino remained lethargic and ate very little. We thought it was either pregnant, older than the documents mentioned, or simply had a bad appetite.”

Over the time Goyana was at the zoo, it was given symptomatic treatment with pills and vitamins, said Dr Selvam. Goyana was cremated on Saturday evening. The zoo authorities said they would inform the International Federation of Rhino about the circumstances of the death. Earlier this month, a male rhino named Raja had died of snakebite. The zoo now has two female rhinos.

Rare births

* A Lion Tailed Macaque was born at Delhi zoo on September 27. The last time endangered animal, native to the Western Ghats, was born at the zoo was in 1988. There are hardly 2,500 macaques left in the world.