What is Difference Between Renal and Kidney Failure

Last Updated on January 4, 2021 by Julia Wilson

What’s the difference between renal and kidney failure?

There is no difference; they are both the same thing. Renal is another word for kidney.

What are the abbreviations CRF, ARF etc.?

CRF stands for chronic renal failure and means the disease is slow and progressive.

ARF stands for acute renal failure and means that the disease has come on suddenly.

What do the kidneys do?

The kidneys perform several vital functions:

  • Filtering waste products from the blood
  • Regulates blood pH
  • Produces hormones which stimulate the bone marrow to produce red blood cells
  • Maintains the correct balance of certain minerals

What is kidney failure?

Kidney failure occurs when the kidneys are damaged, and they lose their ability to perform their functions efficiently.

Chronic renal failure is slow and progressive. It is more commonly seen in older cats. The kidneys contain thousands of filtering units called nephrons; over time these become damaged and die. The kidneys compensate by increasing the size of the remaining nephrons. However, as more and more nephrons die, kidney function is compromised. When 70% of function is lost, you will notice symptoms of chronic renal failure. There are many causes of chronic renal failure including ageing, infections, and toxins. As the cat becomes older, the kidneys have had more exposure to the damaging effects listed above.

Acute kidney failure occurs suddenly. Common causes include decreased blood flow to the kidneys (caused by heart failure, low blood pressure, blood loss), urinary tract obstruction, infection, poisoning, vasculitis (inflammation of the blood vessels).

When the kidneys become damaged, they are not as effective at filtering the blood, which in turn leads to the build-up of toxins in the body. The kidneys also lose their ability to concentrate urine.



The veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. There are several medical conditions with similar symptoms, so he will need to run some diagnostic tests to reach a final diagnosis.

Diagnostic workup:

  • Biochemical profile – A test on the straw-coloured portion of the blood which may reveal elevated BUN (blood urea nitrogen) and creatinine levels.
  • Urinalysis – Analysis of a sample of urine to evaluate the concentration of the urine.
  • Kidney ultrasound or x-ray to evaluate the size and shape of the kidney.
  • Kidney biopsy.


There is no cure for kidney failure and treatment is aimed at medically managing the condition and supporting the kidneys. Treatment may include:

  • Prescription diet.
  • Fluids to treat dehydration.
  • Medications to treat high blood pressure, which is common for cats with kidney failure.
  • Phosphorus binders to control high phosphorus levels which can occur as the kidneys are not as efficient at removing excess phosphorous from the body.
  • Antacids to relieve nausea.

Julia Wilson is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. She enjoys photography, gardening and running in her spare time. Full author bio Contact Julia