Chronic Renal Failure in Cats

What Is Chronic Renal Failure in Cats?

Chronic renal failure (CRF), renal insufficiency, or chronic kidney disease (CKD) are medical terms used to describe when the kidneys are unable to perform their required tasks at a normal level of efficiency.

Kidneys play a vital role in filtering waste from the body. A cat has two kidneys located on each side of the abdomen. The kidneys serve to regulate the body’s balance of fluids, minerals, and electrolytes. They conserve water, protein, and play an important role in maintaining blood pressure and red blood cell production by making a hormone called erythropoietin.

CRF is classified into four stages, based on the severity of clinical signs and laboratory values. These are often progressive, though the timeline may vary:

• Stage I: Clinical signs are usually not apparent

• Stage II: Some clinical signs are noted

• Stage III: Many clinical signs are noted, and cats often appear to feel sick

• Stage IV: A majority of clinical signs are noted and cats are in crisis

CRF is often diagnosed later in a cat’s life, but it can develop at any time. Certain breeds—such as Persians, Abyssinians, Siamese, Ragdoll, Burmese, Russian Blue, and Maine Coon—are predisposed. CRF, if diagnosed at an earlier age, is often associated with a heritable condition. It can also occur secondary to an acute kidney injury, such as ingesting a lily plant.

Symptoms of Chronic Renal Failure in Cats

Clinical signs are often related to the severity of the CRF stage, meaning there are additional, more severe signs noted within stages III and IV rather than with stages I and II. Cats often exhibit symptoms including:

• Increased thirst and urination

• Intermittent vomiting

• Dehydration

• Sores in the mouth

• Foul breath

• Weight loss

• Decreased appetite

Causes of Chronic Renal Failure in Cats

The term chronic, as in chronic renal failure, means that the process has been ongoing and progressive, and cannot be reversed.

For some cats, the disease could have occurred after a serious kidney injury or from a severe infection (including feline infectious peritonitis, feline immunodeficiency virus, and pyelonephritis). It can also occur due to ingestion of a toxic substance like antifreeze or lilies, or certain medications.

For others, CRF could be inherited, as with polycystic kidney disease (a specific type of renal kidney disease) and amyloidosis (a rare organ disease), seen in breeds like Persians and Abyssinians.

CRF could also be attributed to underlying immune-mediated diseases, stroke-like events, clotting disorders, and cancer like lymphoma.

How Veterinarians Diagnose Chronic Renal Failure in Cats

CRF is often diagnosed based on routine blood work and a urinalysis, looking specifically at kidney markers such as:

• Blood urea nitrogen (BUN) is a by-product of protein metabolism. Higher values can often indicate kidney failure.

• Creatinine (CREA) measures how well kidneys are filtering waste from blood,

• Phosphorous in elevated levels typically indicate kidney damage.

• Electrolytes (sodium, potassium, chloride) often fluctuate between high and low levels

• Calcium at elevated levels may be seen with kidney failure.

• Red blood cell count may indicate kidney failure, when low.  

• Symmetric dimethylarginine (SDMA) is an additional test to help determine if kidney disease is present. It can be used for early detection of kidney disease.

• Urine specific gravity is a marker of how diluted or concentrated the urine is. Usually, the higher the number, the more concentrated the urine, and the greater the ability of the kidneys to conserve water.

Your veterinarian will most likely recommend additional diagnostic testing, including:

• A urine protein to creatinine (UPC) ratio to quantify how much protein is being lost in the urine.

• A urine culture for cats in chronic kidney disease (CKD), as they are more likely to acquire urinary tract infections.

• A blood pressure evaluation because cats in CKD are more likely to suffer from hypertension (high blood pressure).

• Radiographs or an abdominal ultrasound to screen for kidney stones or infarcts (areas of dead tissue).

Treatment of Chronic Renal Failure in Cats

Kidney removal is not an option since cats need their kidneys to survive. Dialysis in cats is an extremely uncommon treatment option. However, with early intervention, including routine lab work and annual exams, treatment of chronic renal failure is possible.

CRF can be managed with a combination of medications and proper diet. Your vet will be able to determine which treatment plan is most beneficial, depending on the stage of the disease. It’s important to note for all stages of kidney disease, water should always be available.

Since CRF affects a cat’s hydration, if any additional disease or illness hinders the cat’s hydration, it’s important to treat it promptly with IV fluids.

Recovery and Management of Chronic Renal Failure in Cats

Chronic renal failure is not curable and often progressive (although the timeline is variable). Cats diagnosed early enough can benefit from nutritional management and more frequent veterinary attention, which may include more frequent checkups and blood work.

Cats in stages I and II may be monitored for further progression of signs, and some may be given a prescription diet specifically geared to help the kidneys by limiting the amount of work they have to do. Many cats can go on to have a decent quality of life for many months to years. 

Cats in stages III and IV often require more medical and dietary assistance:

• If secondary anemia is present, erythropoietin injections can be given at the direction of your veterinarian.

• Dietary supplements may be prescribed to help with low potassium.

• Phosphorus binders may be prescribed to treat high phosphorus levels.

• Anti-nausea and anti-emetic (anti-vomiting) medications can be given to cats with a poor appetite, vomiting, or nausea.

• Fluids given either intravenously—or underneath the skin—can help with dehydration. Your veterinarian can show you how to administer these fluids at home.