It was spotted on Hardthorn Road last Friday and taken into care by the charity.
Animal rescue officer Sheena MacTaggart said: “The lamb was found with the number 13 written with purple paint on its side and had a wee plastic coat on.
“Unfortunately the lamb doesn’t have an identification tag or a microchip so we’re appealing to anyone who recognises it to get in touch.
“It’s likely the lamb hasn’t travelled far but it’s struggling to suck the bottle so we’re desperate to find the mother.”
Anyone with information is being urged to contact the Scottish SPCA’s animal helpline on 03000 999 999.