Rex the German Shepherd was so vicious it would take two people to feed him – one to distract him and the other to throw a bowl of food into his enclosure.
He would bark and growl at anything that passed and would even try to poke his head through his run to eat wild rabbits which roamed past.
But when introduced to Geraldine the goose the dog immediately mellowed and the two became inseparable.
At first the owners feared Rex would literally bite his feathered friend’s head off for straying into his territory – but Geraldine took him under her wing.
The pair now like nothing more than going for a walk in the woods and snuggle down to sleep together in Rex’s bed every night.
Staff have been surprised by how close the pair have become and believe the once-angry bird and growling dog bring out the softer side in each other.
“It’s so comical to see them because they love each other to bits,” said Sheila Brislin, who runs the Puriton Horse and Animal Rescue, near Bridgwater, Somerset.
“She just runs around alongside him all day long and whenever we take him for a walk in the woods she has to come too.
“They are very affectionate and he’s always licking her head and kissing her. She snuggles into him and they sleep together every night.
“Normally any bird that crossed his path would have been eaten by now, he’s that kind of dog, but not Geraldine.
“I’ve been doing rescue work since 1997 and seen all kinds of strange animal behaviour, but I’ve never seen anything like this.”
Rex, aged 11, came to the sanctuary after he was found tethered by a chain in a scrapyard eight years ago.
Sheila added: “They were going to give him a lethal injection to put him down because he had bitten everybody at his previous shelter and there was nothing they could do with him.
“They were so scared of him one worker had to distract him at the front of the run while the other threw his food in at the back.
“He was the kind of dog that would put his head through the fence to try and bite the heads off rabbits.”
But the dog mellowed dramatically three months ago when Geraldine arrived at the centre after being rescued from a family unable to cope.
The pair were initially kept apart and Geraldine hung around with Donald the duck and other birds.
“At first we thought he was chasing her and they were fighting about who was boss, but she stood up for herself and that was that, they just fell for each other,” said Sheila.
“They snuggle down together and Rex puts his leg over her to protect her. In the morning they have breakfast together. It’s really sweet to see them.”
But not everybody is smitten with the romance and Rex’s former friend Vera, also a German Shepherd, is upset after being ousted by the green-eyed goose.
“Geraldine doesn’t like Vera at all and makes it quite clear that Rex is hers,” said Sheila.
“She goes on the attack if she comes anywhere near and Vera is scared of her.
“We’ve had to give Vera lots of cuddles and attention so she doesn’t feel left out.”