Police are hunting a suspect who hurled a dog from a cliff into the sea.
Film of the shocking incident has been posted online and has been widely shared.
The person shooting the video clip can be heard laughing above a beach, believed to be near Falmouth, Cornwall, where some cliffs tower more than 100ft high.
The video, which has since been deleted, shows the black and white dog flailing in the air as it tossed from the clifftop into the sea by a young man.
Copies of the video have been removed from social media sites.
Local police tweeted: 'We are aware of an incident of animal cruelty which has been reported in Falmouth.
'This matter is being investigated but please appreciate that we need to do this effectively without intrusion or inappropriate comments.'
The dog is seen swimming desperately to reach the shore, but film clip ends and it is not known what happened afterwards.