Further evaluation is done by analyzing the urine for concentration, bleeding, and infection. Ultrasound exams let us picture the kidneys size, shape and structure.

The waste filtering  part of the kidney is called a nephron.  These nephrons are susceptible to damage from poisons, aging, infection, trauma, cancer, auto-immune diseases, and genetic malformation. These diseases cause  entire nephron to stop functioning.  If damage to nephrons occurs gradually and the surviving nephrons have enough time to hypertrophy, a kidney can continue to function fairly normally with as few as 25 percent of its original nephrons. When the number of functioning nephrons drops below 25 percent signs of disease appear. If damage occurs too suddenly for the remaining nephrons to compensate, acute kidney failure occurs. 

Acute kidney failure is a sudden loss of function that is sometimes but not always reversible.  Management of acute renal failure requires hospitalization, intravenous fluid therapy, and medications to help offset the effects of toxemia associated with loss of kidney function. Intensive therapy is essential to attempt to reverse the process.

Chronic kidney failure may be caused by several different diseases that result in irreversible loss of function that gradually progresses over months or years. Treatment can control discomfort and slow kidney deterioration. Severely affected cats may need hospitalization where treated for vomiting, hydration, electrolyte problems and anemia. Sometimes they are treated at home and monitored in the hospital. Since there are several stages of this progressive disease, treatment for an individual may vary. This may range from simple dietary control and fluid administration, to medicines that binds harmful elements, replace essential electrolytes, increases appetite, controls blood pressure and regulates calcium metabolism. Drugs may also be used to stimulate red blood cell production and appetite.