Evolving Treatments
Just as the nature of disease changes, so does its treatment.
New medications are constantly licensed for use in cats: treatments for thyroid management, heart disease, and pain control are all investigated and sanctioned, and even chemotherapy can be highly effective for certain cancers, sometimes offering hopes of permanent remission.
These treatments lead to ethical questions. How far should such treatment be taken, and when does treatment cease to be in an individual cat's interest? These are difficult questions.
Ethical issues
Medical treatment is always stressful for a cat. It is important to carefully weigh the level of stress against the possible benefit to the cat: the equation will not always be the same as it would for a human.