A DOG owner told by a veterinarian that her beloved pet had to be put down has found the animal in the back of the veterinary clinic in a cage six months later.

The veterinarian, 71-year-old Millard Lucien Tierce, has been arrested for animal cruelty.

Tierce, of Camp Bowie Animal Clinic in Fort Worth, Texas, is accused of keeping Sid, a Leonberger, alive for use in blood transfusions, Star-Telegraph reported.

Fort Worth Police and the Texas State Board of Veterinary Medical Examiners raided the veterinary clinic after Sid’s owner Marian Harris was tipped off by veterinarian technician Mary Brewer, a former employee, that her dog was alive despite being told six months ago he had to be euthanised.

Brewe said the dog was being used for blood transfusions while being kept in a cage most of the day.

“I told her, ‘He’s still here,’ and she’s like, ‘Can he walk?’ and I said, ‘Yeah, he’s here waiting on you. If you came today, he’d walk out and jump in your car,’” said Brewer.

Harris, from the Texan city of Aledo, said last October she gave Dr Tierce permission to put down Sid after she was told that the dog was suffering from a congenital spinal disorder.

The she received a call from Brewer and in a scene straight from the 1992 family classic movie Beethoven she and husband Jamie went to the veterinary clinic and found Sid in a cage in a back room.

“The betrayal is so incredibly intense that nothing you have prepares you for the emotions. There’s anger, there’s joy that you have your dog back, there’s betrayal of this intense trust. And so it’s just really hard to camp on one particular emotion,’ Harris told CBS DFW.

The dog jumped into their mini-van and Jamie and Mirian Harris drove to another veterinary clinic and was told Sid did not need to be put down.

“It was like getting punched in the stomach and then some,” Marian Harris told NBC DFW. “This has rocked our world. My kids are like, ‘How does somebody do this? How does this happen?’”

Police and the State Board of Veterinary Medical Examiners have removed two more dogs from the clinic.

Dr Tierce, a licensed veterinary surgeon since 1966, denied the allegations before he was arrested. He has been released on $10,000 bail.

James Eggleston, attorney for Jamie and Marian Harrises, said three other clients of Dr Tierce have filed complaints with the state veterinary board after news of Sid became public.