This is a decision only the cat’s owner can make, and it is a difficult one. It is not recommended to euthanize a cat, even with FIP, as long as it looks and acts fairly normal. Miracles do happen, but they can’t happen unless they are provided time to happen. However, some owners choose to end suffering at an earlier stage, given the grave prognosis. Many owners decide to put an animal down when it no longer takes pleasure in life. But cats can feign health to the last. There is a myth that if a cat is still purring it is still enjoying life. Research has shown, however, that cats purr even when in extreme pain, it is another way that they mask illness.