Lily, an 18-month-old tabby cat, was found by her owners in her bed at Church Cottage, Aberedw near Builth Wells with injuries caused by two air gun pellets.
Vets confirmed the cat had been shot by an air weapon - and sadly the extent of her injuries meant her front right leg had to be amputated.
Anyone who saw anything suspicious in the area between the evening of September 13 and the following morning has been urged to get in touch with the RSPCA.
RSPCA officers say they regularly deal with animals targeted by air guns - and between January 2020 and the end of June 2021, 371 incidents had been reported to the charity where the caller believed an air gun or rifle had been used to target an animal.
The shooting of Lily has prompted RSPCA Cymru to renew calls for greater regulation linked to the use of air guns - including better education for owners and a thorough explanation of the law.
RSPCA deputy chief inspector Neill Manley said: "Lily's owners found her in her bed with nasty injuries - and sadly vets confirmed she had been shot twice by an air gun.
"It beggars belief why anybody would think it acceptable to take pot shots like this at an innocent animal, like Lily. Sadly, this is something our officers still see all too often - and in 18 months from the start of 2020, some 371 incidents were reported to us.
"Anyone who has seen an air gun being used near Church Cottage at Aberedw near Builth Wells between 12 and 13 September should contact our inspectorate appeal line on 0300 123 8018.
"We're continuing to call for stricter regulations around owning an airgun, basic safety training for owners and a thorough explanation of the law - including outlining our legal obligations towards animals. This could help protect animals like Lily from such callous attacks in the future."