A woman believes her pony, found with its stomach slashed open, was killed by a sadist.

Nine-year-old Caspar was so badly injured a vet had to put him down.

Michele Yates had recently bought a half-share in the pony.

Caspar was kept in a paddock in Rottingdean with four other horses.

Home-help Mrs Yates, 32, of Lower Bevendean, Brighton, received a phone call on Friday afternoon telling her Caspar had suffered a 5cm long cut.

Mrs Yates said: "I've had nightmares about it. I've seen some dreadful cuts to horses but never anything like this."

Caspar was seen looking fit and well on Friday morning but by 2.30pm the police and RSPCA had been called by a dog-walker who saw he had been injured.

The vet thought the pony had been injured by a nail on a fence.

But Mrs Yates said: "There is nothing in that field the pony could hurt himself on."

A shed and tractor had been tampered with and Mrs Yates believes someone went on to the land.

The remaining four horses have been removed.