A pregnant pony miscarried her foal after falling over when a yob rode her for a sick Snapchat video.
Images of the mare being ridden show the unknown youth with his arm in the air, gesturing towards the camera.
Distressing images posted soon after the horrific incident show the mare laying alongside her dead foal.
The images were reportedly taken from a video posted on messaging app Snapchat.
Hollie Cornelius, from Cornwall, shared the awful incident which is believed to have happened on Bodmin Moor.
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She wrote: "To the absolute w*****s who think it's funny to catch and ride heavily pregnant miniature Shetland's on the moors this is a result of your actions.
"The mare clearly couldn't take your body weight as she fell over half way through the video.
"So a dead foal and probably a dead mare by the morning!
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"I hope it was worth it "for the Snapchat" and I hope you're happy with yourselves you absolute low lives!
"I'd just like to ask anyone else to be considerate of the animals on the moors please they do belong to people and they are not toys for your amusement!"
The pictures have been shared 14,000 times and thousands of shocked Facebook users replied to the post, asking for the police to be contacted.
A spokesperson for the RSPCA said: "We urge anyone with any information to call the RSPCA on 0300 123 4999."
