Causes

• Some kidney diseases are congenital, present at birth. There are also external causes such as medications and environmental toxins. Poor diet, high blood pressure, cancer and infections can also lead to kidney problems, according to the ASPCA.
  
  

Subtle Symptoms

• The ASPCA states that litter box aversion and urinating in strange places is a subtle symptom often mistaken for a behavioral issue. This is due to the cat's association of the litter box with painful urination. Changes in appetite and bad breath can also be signs of a kidney disease.
  
  

Severe Symptoms

• Severe symptoms are blood in the urine, vomiting, seizures, and diarrhea. A disease is usually well advanced by the time these symptoms are present, as cited by the PetMD.com website.
  
  

Prognosis.

• Kidney disease is almost always fatal. PetMD.com states that prognosis depends on the stage of disease at detection and the degree of care the cat receives. A cat's life can end anywhere between a few months and a few years after diagnosis.
  
  

Treatment

• PetMD.com recommends a protein-restricted diet and fluid therapy to increase the longevity of a cat after diagnosis. Hydration is usually a key element in aiding survival.