An Adelaide animal shelter has installed a state-of-the-art security system to stop people breaking in at night to try to steal their confiscated animals back.

The RSPCA said a donor paid thousands of dollars to buy the surveillance system and the installation cost was waived.

RSPCA chief executive Tim Vasudeva told 891 ABC Adelaide there had been a number of attempts to break into the shelter at Lonsdale, one of them successful.

"Someone was successful in retrieving a dog which had been seized by council," he said.

"A dog may have been seized by a council, perhaps if it's attacked another dog or bitten somebody."

He said surveillance kept all the animals safe and helped prevent damage or injuries if people considered trying to scale the perimeter fencing.

"What we're really looking at now is extensive systems with lots of cameras and immediate responses with alarms and the police," he said.

"That's a beef-up of what we had before.

"We're concerned about all the animals down there so having a state-of-the-art system is really imperative for us."

Mr Vasudeva praised the donor and the system installer.

"The RAA didn't charge us for the installation, and the system itself was actually paid for by a kind donor, who's a lovely lady who's been supporting us for a while," he said.