Authorities in Puerto Rico are investigating what they say is one of the worst cases of animal abuse they've seen in the U.S. territory: a puppy found alive with all four legs largely cut off, leaving exposed bone.

Rescuers said Tuesday they found the puppy over the weekend along the north coast.

The black puppy nicknamed "Ocean" was euthanized on Sunday. Mariel Rojas, who runs a local animal rescue group, said she rushed the dog to a veterinarian, but was told that its bones were rotting and the infection too large to be treated.

The case has sparked outrage on the U.S. mainland and revived calls to crack down on animal cruelty in Puerto Rico, which has been slowly recognizing animals' rights and prosecuting such cases.