Police are investigating an incident where a filly was assaulted in the village of Croft, Leicestershire.
The pony’s injuries were so severe that she had to be put to sleep a few days later.
The two-year-old New Forest pony was found in her field with her legs tied together two weeks ago by her owner Matt Bryan.
Nine other horses in the field were unharmed.
“Some sick person has attacked her — we strongly believe she was also sexually assaulted,” said Mr Bryan.
“We didn’t realise the extent of the injuries at first, but the flesh on her legs rapidly deteriorated and started to fall off.
“The vet said this has all the hallmarks of previous assault cases in the area.”
The filly’s back legs had been so tightly tied that her blood circulation was cut off.
She was bought as a wild foal from the New Forest, and belonged to the Bryans’ three-year-old daughter.
Mr Bryan has 18 horses, including broodmares, at his yard and is concerned for their safety.
“The field where the filly was attacked was only 500 yards from our house, with neighbours overlooking,” he said.
“But I’ve moved them all [the horses] out. Some have gone to a friend’s fields; the others are crammed into my stables. I’d rather they were squashed and safe.”
Leicestershire Police confirmed that they are investigating the incident.
“A horse was left with its legs tied up in a field in Croft at some time between Sunday 9 January and Monday 10 January, and enquiries are ongoing,” said a spokesman.