A Scottish SPCA staff member, who lives on site, discovered the feline on their doorstep at 7.40am on Monday (1 June). He is now in the care of the Scottish SPCA and has been named Mr Pickles.
Centre assistant manager Kenny Sharpe said, "Whoever left Mr Pickles rang the doorbell and must have left very quickly as they were nowhere to be seen.
"Mr Pickles was found inside a red and white plastic pet carrier with a handwritten note on top which said 'Please look after this cat. It is being mistreated.'
"He is a semi-long haired tabby cat aged around three to four years old, with a red elastic collar. He is friendly but absolutely terrified.
"At this stage we don't know who abandoned Mr Pickles or why. Although the note stated he was being mistreated he seems in good condition.
"If anyone recognises Mr Pickles and can shed any light on the situation we would ask them to contact us on 03000 999 999. We will care for him until we can find him a loving new home."
Anyone with information is being asked to contact our Animal Helpline on 03000 999 999.