Two alpacas kept at a nursing home in north-west England were attacked by two men with garden furniture on Aug 4.
CCTV footage taken at Danesmoor Residential Care Home, in Haslingden, shows the men entering the animals' enclosure after grabbing nearby plastic chairs and a wooden bench.
The footage shows the men throwing them at the alpacas as the animals run away. One man is shown chasing them with a broken chair leg.
The animals, whose names are Bill and Ben, are brothers and have been kept at the home for five years, ever since they were very young.
Community Beat Manager PC Claire Scott described the attack as a disgrace.
"This unprovoked and mindless attack on two defenceless animals is a disgrace to say the least and we will do all we can to identify these men," she said.
"Bill and Ben are there for the elderly residents to enjoy and this sort of behaviour is simply intolerable," she added.
Lancashire Police said the alpacas did not suffer any serious injuries and a vet gave them a clean bill of health.