It is believed that the owners laughed cruelly when their dog bit two ponies.
They then left, leaving the animal behind.
It happened at Little Farthingloe Farm, Folkestone Road, Dover, at 3pm yesterday (Tuesday).
Management of the farm restaurant and store said in a Facebook post: “We are deeply shocked that the owners of the dog left, apparently laughing, while he was in the field attacking the ponies. . “
Management has since explained that when the dog attacked customers and restaurant staff were alerted and run over.
Two people in the car then took off, leaving the dog behind and a third person accompanying them, a woman.
The animal has now been taken in by a dog sitter and police have spoken to the remaining woman, officials said.
The victims were Oscar, a white pony, and Dudley, a black.
The two were seen by a vet and given antibiotics and anti-inflammatories to help relieve the wounds.
They remained in shock yesterday but have been monitored in case further treatment is needed.
The management post said yesterday: “Thank you very much to all the customers and staff who have helped with Oscar and Dudley this afternoon.
“They both seem still in shock but have had dinner.
“The police are investigating and hopefully they (the dog owners) are located.”
Kent Online has contacted police for further details and updates.
Read more: All the latest news from Dover