Both pets were discovered at the charity’s Edinburgh and Lothians Animal Rescue and Rehoming Centre at Belernoon on Monday afternoon.
An SSPCA spokeswoman said: “A white cat was dumped in a grey and white pet carrier while a light ginger cat was found loose next to a cardboard box which had disintegrated due to the heavy rain. The male cats have now been named Angelo and Arnie.”
Kenny Sharpe, the centre’s assistant manager, said: “Angelo was discovered at around 1pm by a woman who was handing an injured pigeon into the centre. A member of staff then spotted Arnie around 45 minutes later. We think the reason he wasn’t spotted at the same time is because there was little left of the box and he was roaming loose in the grounds of the centre.
“Unfortunately, our CCTV footage has not picked up anyone leaving Angelo and Arnie but we do believe they were dumped by the same person and we are very keen to hear from anyone who recognises them.”
He added: “While someone may have thought they were doing the right thing by leaving them outside our centre, it’s unacceptable to abandon animals under any circumstances, as well as an offence.
“Our centre is close to a country road and Arnie did run onto it while we were trying to contain him, so it’s very lucky he wasn’t hit by a car. We’re glad that Angelo and Arnie are now safe and we’ll soon find them the loving home they deserve.”
The two cats are now being cared for at the Scottish SPCA’s Lanarkshire Animal Rescue and Rehoming Centre in Hamilton.