Complex sentence: Accepted wisdom is that there is no cure for FIP; treatment is symptomatic and palliative only, i.e. typically the owner is advised to make the cat as comfortable as possible until it becomes clear that the cat is suffering.
Split into simpler sentences: Accepted wisdom is that there is no cure for FIP, treatment is symptomatic and palliative. Typically the owner is advised to make the cat as comfortable as possible until it becomes clear that the cat is suffering.