There are four stages of chronic renal failure in cats. Stage I has no obvious clinical signs, with mildly elevated blood tests for serum creatinine and blood urea nitrogen. Stage II may show signs of polyuria, mild anaemia, dehydration and heart failure. Stage III may present with oliguria, moderate and severe anaemia, creatinine and urea nitrogen rising to 130% or more, etc. Stage IV is the uremic phase, where a variety of clinical signs appear, with neurological signs and skeletal deformities being the most obvious.
