Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

Acute renal failure (ARF) is a serious form of kidney failure which usually comes on suddenly and which is often triggered by a particular event or "insult" to the kidneys.
ARF is difficult to treat but in some cases the cat may make a full recovery. In other cases, the cat will be left with residual kidney damage.
It is possible to have ARF and CKD simultaneously. This is known as acute on chronic renal failure. Patient UK explains more about this.

Symptoms Back to Page Index

With hindsight, you may realise that your CKD cat was exhibiting subtle signs of illness such as increased drinking and urination, poor appetite and weight loss.

In contrast, since ARF comes on suddenly, there may have been no signs at all of illness previously, so you will probably notice a dramatic change in your cat. ARF cats often look lethargic, stop eating and vomit. They may urinate more, less or not at all (which is a medical emergency, as ARF is generally). They may exhibit reduced urination (which is sometimes the cause of the ARF if there is a reason for it such as a kidney stone).

Diagnosis Back to Page Index

Cats with ARF will normally present with extremely high bloodwork, with creatinine often over 10 USA (850 international), although it may even be twice as high as that. They usually have metabolic acidosis. At initial diagnosis, they may have low calcium levels (LINK), which may then rise as treatment is begun, to such an extent that they may then become too high. Unlike cats with CKD with such high bloodwork, however, ARF cats are often not anaemic, at least not initially.

They may exhibit reduced urination (which is sometimes the cause of the ARF if there is a reason for it such as a kidney stone), and this can cause potassium levels to rise to dangerously high levels (high potassium levels are known as hyperkalaemia).

For cats with ARF, it is often worth getting an ultrasound performed to see if this can shed some light on the cause - cats with CKD tend to have small, shrunken kidneys, whereas cats with ARF often have enlarged kidneys.

Causes Back to Page Index

Possible causes include:

Toxins such as lilies or antifreeze
Infections, blood clots in the kidney, kidney stones, or obstructions which block the flow of urine
Certain medicines, such as meloxicam (Metacam)
Kidney infections (pyelonephritis) may cause ARF.

Lilies

Most types of lily are extremely toxic to cats. It is not necessary for the cat to nibble on the leaves - even if the cat simply brushes against a tiny amount of pollen, then later licks that area, it can cause ARF. Do what I do: don't allow lilies in your home.

Cats and Kittens Magazine has information from the ASPCA on the dangers of lilies.

Purdue University School of Veterinary Medicine has information on lily toxicity for cats.

Cats Protection also has information on lily toxicity.

Acute renal failure caused by lily ingestion in six cats (2002) Langston CE Journal of the American Veterinary Medical Association 220(1) pp49-52 reports on six cats who developed ARF after ingesting Easter or tiger lilies. Three cats survived, two died, and one was put to sleep with no treatments being attempted. The chance of survival was lower in cats with reduced or no urination.

Antifreeze (Ethylene Glycol)

Anti-freeze is a common cause of acute renal failure because unfortunately cats seem to like the taste of it. Cats may sometimes appear to recover, but will then become ill once again; therefore it is critical to seek veterinary treatment as early as possible, even if the cat appears to be recovering. Early treatment greatly influences the cat's chances of survival.

US Food & Drug Administration - antidote for antifreeze poisoning discusses the best treatment for antifreeze poisoning.

Pet Place - three pages of detailed information on antifreeze poisoning. No need to register to read the article, just click Close on the registration box which initially blocks you from viewing the article.

Washington State University College of Veterinary Medicine - information about antifreeze poisoning.

Renal Calculi (Stones) and Obstructions

Renal calculi (kidney stones) may cause acute renal failure. This is usually because they lodge in the ureter (the tube that leads from the kidneys to the bladder) and allow waste products that would normally be excreted by the bladder to build up in the kidneys - this is called obstructive nephropathy. The diagnosis can usually be confirmed via ultrasound. The ultrasound may show one small kidney and one enlarged kidney (see renomegaly).

Kidney Infections (Pyelonephritis)

Cats with acute kidney infections may develop acute renal failure. In some cases, successfully treating the infection will lead to the cat making a full recovery. Kidney infections may need to be treated with intravenous fluids. A lengthy course of antibiotics is also necessary in most cases. See Urinalysis for more information.

Advanced Veterinary Care Center describes the case of a seven month old cat with CKD who developed acute renal failure on top of the CKD because of a kidney infection.

Meloxicam (Metacam)

Meloxicam is a non-steroidal anti-inflammatory drug (NSAID) available in both injectible and liquid (oral) form. In the USA meloxicam is only approved for use in cats in its injectible form. This is because it is intended to be a one-off treatment as a painkilling injection following surgery. In Europe it is approved in both the injectible version (for one-off use in cats following surgery) and in oral form (for longer term pain management e.g. for use in cats with arthritis).

Unfortunately in some cases meloxicam appears to have caused permanent damage to the kidneys, with the result that a number of cats seem to have developed acute or chronic renal failure after taking it.

There is more information on meloxicam on the Causes of CKD page.

Treatments Back to Page Index

Acute renal failure caused by toxins is usually treated with several days of hospitalisation on intravenous fluids. Various medications may also be given to treat concurrent problems such as high potassium levels or metabolic acidosis. Do not accept just one day of treatment, most cats need several days.

Cats with kidney stones usually have calcium oxalate stones. These cannot be dissolved through diet, so are usually treated initially with IV fluids and diuretics in an attempt to flush the stones out. See the Kidney Stones page for more information.

Urinary tract blockages may also be caused by the opposite problem, struvite crystals (see Harpsie's Website for more information). This type of blockage also needs to be treated with hospitalisation on IV fluids and in some cases may require surgery, but following the initial crisis it often be managed with dietary modifications at home.

The Causes of CKD page gives details of the recommended protocol for treating acute renal failure associated with the use of Metacam.

Although ARF can be difficult to treat, if the cat survives the initial crisis, he/she can often regain much or sometimes all of his/her normal kidney function. However, sometimes cats who experience ARF will have some residual damage, and will be left with CKD.

Links Back to Page Index

Which is it? Acute renal failure versus chronic kidney disease (2009) is a helpful overview by Dr GF Grauer, though some may find it a little technical.

Acute renal failure in the dog and cat: causes and outcomes (2003) is a presentation by Dr LD Cowgill to the World Small Animal Veterinary Association World Congress 2003.

Pet Place - helpful information about acute renal failure. No need to register to read the article, just click Close on the registration box which initially blocks you from viewing the article.

Renal disease/urology (2003) is a paper by Dr S Ross which has a helpful section on differentiating ARF from CKD. It also talks about the symptoms of acute on chronic, where a cat who already has CKD suddenly develops ARF on top, often while the patient is already in ICU.

Acute uremia in cats (2008) Veterinary Focus 18(2) is a more recent paper by Dr Ross.

Dr Katherine James - a site by a feline nephrologist who recommends this website to those dealing with CKD. Also technical but useful.

Acute intrinsic renal failure - causes and prevention (2007) Chew DJ Presentation to the World Small Animal Veterinary Association World Congress 2007.

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This page last updated: 21 November 2011

Links on this page last checked: 16 December 2010