Phil Latham, who farms near Nantwich, Cheshire, made the heartbreaking discovery when a member of staff was doing a routine check of the animals at about 7pm on Friday (August 9).
"It makes me beyond mad to know how long it took to do so much damage. The calves must have been traumatised for hours. It took four police officers, two vets and three of us from the farm to treat them for puncture wounds and tears," he said.
Mr Latham said a Rottweiler and a Rhodesian Ridgeback were roaming the farmyard off the lead.
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"The calves had deep wounds up to your knuckles, right into the muscle," he said.
"The poor things must have suffered incredibly. Our vet said it is the worst dog attack she has ever seen. We were treating their injuries for over three hours."
Mr Latham, who runs the Kelsall Hill Equestrian Centre, believes the same dogs were responsible for another attack on eight of his calves about two years ago.
He added: "How bad does it have to be before dogs are destroyed? Our vet has swabbed the calves and I want the dogs DNA tested so we can get definitive proof those dogs attacked my calves."
Cheshire Police are investigating.
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