Kidneys have many functions:

  • Balance chemicals in the blood
  • Filter out waste from the blood as urine
  • Regulate blood pressure
  • Regulate calcium
  • Stimulate red blood cell production
  • Conserve water

The kidney’s filtering system is made of thousands of microscopic tubes called nephrons. A kidney can still function if some nephrons are damaged and stop working. However, if they stop working too suddenly for the good nephrons to compensate or if most of the nephrons stop working, kidney failure occurs.

The immediate risk of failing kidneys is that they cannot clear the blood of dangerous toxins.

There are 2 types of kidney failure:

  1. Acute kidney (renal) failure (ARF): a sudden loss of function. This occurs so suddenly that the functioning nephrons don’t have time to compensate. Acute kidney failure is oftenreversible if diagnosed in the early stages and treated aggressively.
  2. Chronic kidney (renal) failure: A loss of function that occurs gradually over months or years. The kidneys lose their ability to filter the blood of wastes. CRF can lead to total kidney failure.


There are many ways for the nephrons to become damaged:


  • Ingestion of harmful substances such as antifreeze and rat poison
  • Cancer
  • Heart failure
  • Hypotension (low blood pressure)
  • Clotting disorders
  • Intestinal disease
  • Dehydration
  • Bacterial infection (bacteria invade the urinary tract and travel to the kidneys)
  • Certain medications (some antibiotics and chemotherapy drugs)


  • Autoimmune diseases (the immune system attacks the body’s organs)
  • Cysts in the kidneys which grow and destroy tissues
  • Genetics


When the kidneys are not removing wastes from the body, your cat will show many signs:

  • Depression
  • Dehydration
  • Excess thirst
  • Lack of appetite and weight loss
  • Vomiting (may contain blood)
  • Diarrhea (may contain blood)
  • Weakness
  • Foul-smelling breath
  • Seizures

Some additional signs:


  • Stiff-legged gait and arched back (a sign of painful kidneys)
  • Frequent or no urination


Chronic disease progresses over a period of years and can go unnoticed. When signs finally appear, the disease is already advanced. But with proper treatment, some cats with chronic kidney failure live comfortably for years after diagnosis.

  • Increased urination
  • Bleeding or bruising easily


Your veterinarian may perform the following:

  • Blood tests: high levels of urea and creatinine in the blood indicate kidney failure
  • Urinalysis: with healthy kidneys, urine is concentrated and doesn’t contain blood or protein
  • X-rays, ultrasounds
  • Kidney biopsies



Aggressive action must be taken:

  • Hospitalization
  • Intravenous fluid therapy to remove the toxins in the blood
  • Medications


If the kidneys are severely damaged, medical treatment will not be able to reverse the condition. But with early diagnosis and aggressive treatment, many dogs will resume a normal lifestyle for a while.

  • Hospitalization
  • Intravenous fluid therapy to remove the toxins in the blood
  • Medications

There are more intense treatment options available:

  • Dialysis (artificial blood filtering): very expensive and requires several hours of treatment a few times a week
  • Kidney transplants: very expensive and there are few long-term survivors

Home treatment for chronic failure:

  • Make sure your cat always has access to fresh water
  • Maintain a stress-free daily routine to encourage eating and drinking
  • Dietary management: restrict the amount of protein your cat eats. This will decrease the amount of waste in their blood stream, and relieve the workload of their kidneys


Kidney failure can develop naturallyas the kidneys wear our. Since this happens with age, there is no real preventative measure; it can only be treated.

Ingestion of even a small amount of antifreeze can lead to acute kidney failure and death. It’s more common with outdoor cats that are more often exposed to antifreeze.



ARF is a life-threatening condition, with a guarded prognosis.

The prognosis is better if infection was the cause, rather than a toxic substance.

The long-term prognosis for recovery depends on the amount of kidney damage that has occurred, because kidney tissue cannot re-grow.

Your veterinarian will do blood and urine tests during treatment to see how well the kidneys are responding. If there is a positive change within the first 48-72 hours of therapy, there is a good prognosis. If there is no change, the prognosis is weak.


Most cases of CRF progress slowly. Therefore, with proper management, your cat can have a good quality of life for several years.