renal failure in cats

Renal Failure in Cats

Chronic Renal Failure (CRF) in cats is a terminal illness. It is one of the more common causes of death in older cats. CRF occurs when ~70% of kidney function is destroyed.


Older Cat with Renal Failure


Dear Simba, - My 14 year old cat, Cookie, apparently has a kidney infection.
My vet says her creatinine and BUN levels are very high. Please explain to me what these mean. Do you have any idea of Cookie's chances are? My vet has her on fluids and antibiotics for 4 days. Is there any thing else I can do? Any info and help is greatly appreciated. -Lucy

Dear Lucy,
It's possible Cookie may be experiencing Chronic Renal Failure.

Chronic Renal Failure (aka CRF) occurs when ~70% of kidney function is irreversibly destroyed. Kidney function consists of the work done by tiny units called nephrons. Nephrons are responsible for filtering out toxins and wastes, like BUN and Creatinine, from the bloodstream. The toxins and wastes are normally concentrated and eliminated through urine. When the nephrons are destroyed, the kidneys are unable to filter out toxins, this in turn causes uremic poisoning. Thus, tests that show elevated levels of Creatinine and BUN indicate the possibility of CRF. About Creatinine & BUN:
  • BUN (blood urea nitrogen) A waste product excreted through the kidneys. BUN is is reflective of diet. An increase in BUN can also be due to dehydration (a symptom of CRF and many other problems). Normal BUN levels for felines are in the range of 14 - 36 mg/dl.

  • Creatinine A waste product excreted through the kidneys. It is indicative of declining kidney function. Normal Creatinine levels for felines are in the range of .6 - 2.4 MG/DL.
CRF is a terminal illness and is one of the more common causes of death in older cats. It can result from:

  • Kidney inflammation

  • Renal diseases

  • Renal lesions

  • Bacterial infection in kidney

  • Feline leukemia

  • FIP
  • High blood pressure

  • Toxins

  • Immune system problems (i.e., FIV

  • Inflammatory Bowel Disease

  • Pancreatitis

  • Diabetes


With specialized treatment, many CRF cats are able to live months to years after diagnosis. The goal of treatment is to ease the burden put on the kidneys and to prevent dehydration. This means diet & fluid therapy:
  • Diet - CRF treatment diets must be low in phosphorus and are often prescription based.

  • Fluid Therapy - CRF cats are often given distilled water, because tap water and bottled water are hard on the kidneys. Some treatments involve the subcutaneous fluids. This is something you must discuss with your vet.
Other things to discuss with your vet revolve around calcium restoration, potassium supplements, phosphate binders, hypertension medicines and appetite stimulants.

I hope that Cookie makes it through! The most important thing is that you and your vet start her on a treatment program!! Simba