A South Mimms animal centre is searching for the owner of a dog which was left by the roadside to die.

The tan-coloured mastiff was found just a few hundred metres from the RSPCA centre in Packhorse Lane, Southridge, last week.

Named Nellie by staff, she was discovered lying on a grassy bank in freezing conditions.

She was rushed to Wood Street Veterinary Hospital, in Wood Street, Barnet, where a two-day battle to save her started. But the dog's problems were too great and she was put to sleep to avoid further suffering.

Vet Tony White said: "She was underweight, her back legs were partially paralysed and she was in a lot of pain with her spine.

"It amazes me that someone would dump a dog in that condition in the middle of the night in winter. I just don't understand the cruelty involved."

Shortly after Nellie was found, a nurse at the Wood Street hospital received a phone call from an anonymous man asking how the mastiff was.

RSPCA staff are keen to speak to whoever made the call.

Mona Jorgensen, deputy manager at the Southridge centre, said: "Time and again we witness the pure cruelty by humans to pets. The disposal of this beautiful mastiff in this cold and callous manner shows how some individuals still choose to behave irresponsibly and cold-heartedly when an animal becomes a burden, either financially or emotionally."

The RSPCA is asking anyone who has information about the dog's owner to call the charity in confidence on 0300 123 0704.