A member of the public found the animal unresponsive opposite Dunimarle Castle in Culross on Sunday.
The female grey tortoiseshell cat was blind and very thin with overgrown nails.
After being examined by a vet, it was discovered she had end stage renal failure and the decision was made to put her to sleep on welfare grounds.
Now the Scottish SPCA is appealing to the public to help.
Inspector, Mairi Wright, said, “We are appealing to the public for any information regarding how the cat came to be in this condition.
“It would have taken a considerable amount of time for the cat to become as thin as she was and for her nails to become as overgrown as they were.
“This would have caused her considerable pain and discomfort.
“As the cat was suffering from terminal kidney failure, it would appear that no veterinary treatment had been sought and we imagine she would have been suffering due to this.
“The cat was blind so if someone did abandon this cat then they would have caused her further suffering by leaving her outside on her own.”
Contact the SSPCA confidential animal helpline on 03000 999 999.