Cats have four stages of kidney failure, starting at stage one, or kidney insufficiency, and progressing to end-stage kidney failure in stage four, states All Feline Hospital. At stage one, kidney function is 33 percent or higher, but less than 100 percent.
In stage two, or late stage kidney insufficiency, kidney function is between 25 and 33 percent, states All Feline Hospital. At this stage, cats begin to increase their water intake and may develop hypertension. In stage three, or early kidney failure, kidney function is between 15 and 25 percent. Symptoms include increased drinking, vomiting, decreased appetite and secondary kidney infections. In stage four, kidney function is less than 15 percent. Most cats at this stage live only a few months.