Sixteen-year-old Georgie Girl was attacked on Wednesday night in a field in Chew Lane, Upham, Hampshire.
Her owner, Kate Buckett, 38, said: 'Feelings are running high - I can't believe that anyone could be this deviant. I just hope the police get him before anyone else does or there won't be much of him to interview.'
Police believe the culprit may be the same person responsible for 24 similar attacks in Hampshire in the past 12 months. A police spokesman said: 'The specialist horse attack squad from Alton is already investigating this attack and there is every possibility it is linked to the previous attacks.'
Mrs Buckett said: 'The first I knew of the attack was when my groom girl came running in saying she had seen some blood on the horse. I thought Georgie Girl had miscarried. But after the vet inspected her it was obvious she had been terribly assaulted.'
Mrs Buckett and her husband David, a farmer, have owned the 16-hand horse for several years.
Detectives are looking for a man and a woman who were seen parked in a black BMW in the area on Wednesday afternoon.
In another attack, two ponies had their manes and tails clipped as they grazed in a field near Landford, Wiltshire.Reuse content