Dog found alive six months after he was supposedly put down.

For Marian Harris it was a difficult decision to have her beloved Leonberger dog, Sid euthanized.

Her veterinarian, Millard Lucien Tierce told her and her husband, Jamie last October that they had no choice, four-year old Sid was suffering from a congenital spinal disorder.

So imagine their horror when they found out that Sid was in fact alive – six months later – and cruelly being kept by the veterinarian in a cage and used for blood transfusions.

The devastating scene has played out in the US city of Fort Worth, Texas.

Marian Harris heard from a former employee of the vet’s clinic that Sid was being imprisoned.

Harris said she and her husband marched into the Camp Bowie Animal Clinic and found Sid in a back room.

“He was able to walk and jump in the back of my minivan so it was an excitement to be reunited,” Harris said.

“The betrayal is so incredibly intense that nothing you have prepares you for the emotions,” Harris told CBS News Dallas/ Fort Worth

“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.”

The allegations are being investigated by the local police and the state Board of Veterinary Medical Examiners.

Animal control have since removed two other dogs from the clinic.

Tierce, spoke to media calling the accusations “a bunch of hooey”.

He said he had kept Sid alive because he couldn’t bear to put him down.

“The lady wanted me to euthanize their dog, but I just couldn’t bring myself to do it,” Tierce told The Star Telegram.

Marian Harris has since had Sid checked out by a different vet and he has been given a clean bill of health and reunited with his owners.