Bottlenose dolphin has been euthanized

A bottlenose dolphin that strayed into a river off Boston Harbor was euthanized when it beached itself on a mud bank.

Tony LaCasse of the New England Aquarium told the Braintree Forum that a necropsy determined that the dolphin, which normally lives in the open sea miles offshore, suffered from pneumonia and had a parasite in its aorta. It probably ventured into the harbor because it was sick, although it continued to be a strong swimmer in its last days.

The dolphin, a 500-pound 8-foot male, had attracted crowds to the Monatiquot River in Braintree since it was spotted there Friday.

On Monday, veterinarians gave the dolphin a combination of a sedative and paralyzing agent. LaCasse said that the animal gave out a few "pops and whistles" as it died.