The branch has done away with cages for felines waiting for adoption at its Stuart St shelter and created two separate open space play areas, one for cats and the other for kittens.
Shelter manager Dave Barnard said the branch had 12 cats ready for adoption.
They now had toys, sofas, cushions, caves and climbing poles to occupy them as they waited for new homes.
The longest resident, Debbie, has been waiting for two years for adoption.
The branch is raising funds for a new shelter in central Oamaru, and has made its existing premises more cat-friendly in the meantime.
Mr Barnard said the cats were a lot happier being able to roam free, compared to being caged.
"The cages used to create havoc with their mental state," he said.
With more than one cat to a cage, there was a danger of pathogen or parasite spread or cat fights.
It was also better for people visiting the shelter.
They could interact with the cats in the play area before deciding on whether to adopt.
Several cages have been retained for cats recovering from illness, or for "time out" if they misbehaved.
