The RSPCA fears a cat which was dyed pink and dumped was the victim of a "sick prank".
The animal charity is trying to trace the owner of the animal, which was thrown over a fence into a back garden in Swindon, Wiltshire.
The dye is not toxic but failed to budge with washing and the vet caring for the cat - nicknamed Pink - said further washes could cause her a lot of stress with little result.
Veterinary surgeon Penny Gillespie, who is looking after Pink at Cheldene Veterinary Centre and Boarding Cattery in Aldbourne, Marlborough, said: "We have no idea what the dye is or how long it will last. It is clearly not toxic but still unpleasant.
"The person responsible has covered her thoroughly all over but avoided putting any around the animal's eyes and nose.
"Further washing would stress Pink and probably would not help to remove the colour so it will be case of waiting for it to grow out."
The resident who saw Pink being thrown into their back garden in Wesley Street, Swindon, at 10.30pm on Saturday did not see the person responsible but called the RSPCA.
The naturally white female cat, aged between one and two years, is in good health and the fur pattern around her neck suggests she wore a collar until recently.
An RSPCA spokesman said it cannot rule out the possibility the cat is someone's missing pet which was dyed as "a sick prank".
Animal welfare officer Carl Hone, who is investigating for the charity, said: "When I got the call I thought perhaps it would be a cat with something natural on their coat or which had rubbed against wet paint but this poor creature has been dyed completely pink, except around her eyes and nose, so she looks like she has a white mask on.
"We are very keen to trace the person responsible for doing this to the cat and I would urge anyone with information, or who knows who she belongs to, to please call the RSPCA."
Anyone with information about the incident is asked to call the RSPCA cruelty and information line on 0300 1234 999.