The cat-only rescue facility shut its doors last week, citing increasing costs and a declining number of animals needing care as the reason.
The remaining animals will continued to be cared for until adoptions are processed.
SPCA animal services general manager Dr Corey Regnerus-Kell said it was no longer financially sensible to keep the facility running.
Any incoming animals requiring care would be transferred to SPCA centres in Dunedin and Timaru.
SPCA would be creating a new field officer and community support to help people in the area access its services.
"I am confident this new model will allow us to service the local community, while optimising our resources."
The organisation received no government funding, instead operating on donations.
The money that would have been spent on operating the facility would now be spent on other programmes, such as desexing.
"We have a responsibility to put these kindly generated funds to the best use to help animals in need."
Street Cats South Canterbury programme director Karen Sole said the closure of the Oamaru SPCA meant fewer cats would be rescued, but she understood why the decision was made.
"Donations just don’t come forward like they used to."
She disagreed there was a declining demand for the service, as Street Cats took in more than 600 felines a year and was often at capacity, meaning it could not take any more.
It took in many wild cats from the Oamaru and Waimate areas.
"I’ve been doing this for 10 years. It’s not reducing."
The Oamaru SPCA did not rescue many cats, but the services it provided were valuable for the community, such as providing neutering vouchers for those on low incomes, she said.
She was pleased those services would continue.
