Chronic Kidney Disease in Cats: Symptoms and Treatment

Chronic kidney disease (CKD), also called chronic renal failure (CRF) or renal insufficiency, occurs when a cat’s kidneys can no longer perform their required tasks at a normal level of efficiency.

CKD is progressive and cannot be reversed, but cats diagnosed early can benefit from nutritional management and more frequent veterinary care.

What Is Chronic Kidney Disease in Cats?

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

The 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 regulate the body's balance of fluids, minerals, and electrolytes. They conserve water and protein and play an important role in maintaining blood pressure and red blood cell production by making a hormone called erythropoietin.

Stages of Chronic Kidney Disease in Cats

CKD is classified into four stages based on the severity of clinical signs and laboratory values. These stages 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.

CKD is often diagnosed later in a cat's life, but it can develop at any time. Certain breeds—such as Persians, Abyssinians, Siamese, Ragdolls, Burmese, Russian Blues, and Maine Coons—are predisposed.

CKD 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.

What Are the Symptoms of Chronic Kidney Disease in Cats?

Symptoms of chronic kidney disease in cats can include increased thirst and urination, intermittent vomiting, dehydration, mouth sores, foul breath, weight loss, and decreased appetite.

Clinical signs are often related to the severity of the CKD stage, with additional, more severe signs noted in stages III and IV than in stages I and II.

Symptoms may include:

• Increased thirst and urination
• Intermittent vomiting
• Dehydration
• Sores in the mouth
• Foul breath
• Weight loss
• Decreased appetite

What Causes Chronic Kidney Disease in Cats?

Chronic kidney disease in cats can develop after a serious kidney injury or severe infection, from toxic substances or certain medications, from inherited conditions, or from other underlying diseases.

The term chronic means that the process has been ongoing and progressive and cannot be reversed.

Kidney Injury and Infection

For some cats, CKD may develop after a serious kidney injury or severe infection, including feline infectious peritonitis, feline immunodeficiency virus, and pyelonephritis.

Toxins and Medications

CKD can also occur due to ingestion of a toxic substance, such as antifreeze or lilies, or certain medications.

Inherited Conditions

For other cats, CKD may be inherited, as with polycystic kidney disease and amyloidosis (a rare organ disease), which are seen in breeds such as Persians and Abyssinians.

Other Underlying Conditions

CKD may also be attributed to underlying immune-mediated diseases, stroke-like events, clotting disorders, and cancer such as lymphoma.

How Is Chronic Kidney Disease in Cats Diagnosed?

Chronic kidney disease in cats is often diagnosed using routine blood work and a urinalysis to evaluate kidney-related markers. 

Additional testing may include a urine protein-to-creatinine ratio, urine culture, blood pressure evaluation, X-rays, or an abdominal ultrasound.

Blood and Urine Tests for Chronic Kidney Disease

Kidney markers evaluated through blood work and urinalysis may include:

• Blood urea nitrogen (BUN): A by-product of protein metabolism. Higher values can often indicate kidney failure.
• Creatinine (CREA): Measures how well the kidneys are filtering waste from the blood.
• Phosphorous: Elevated levels typically indicate kidney damage.
• Electrolytes: Sodium, potassium, and chloride often fluctuate between high and low levels.
• Calcium: Elevated levels may be seen with kidney failure.
• Red blood cell count: A low red blood cell count may indicate kidney failure.
• Symmetric dimethylarginine (SDMA): An additional test that helps determine if kidney disease is present and can be used for early detection of kidney disease.
• Urine specific gravity: 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.

Additional Testing for Chronic Kidney Disease

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

• Urine protein-to-creatinine (UPC) ratio: Used to quantify how much protein is being lost in the urine.
• Urine culture: Cats with chronic kidney disease (CKD) are more likely to acquire urinary tract infections.
• Blood pressure evaluation: Cats with CKD are more likely to have hypertension (high blood pressure).
• Radiographs or abdominal ultrasound: Used to screen for kidney stones or infarcts (areas of dead tissue).

How Is Chronic Kidney Disease in Cats Treated?

Chronic kidney disease in cats can be managed with a combination of medications and proper diet. Your veterinarian will determine which treatment plan is most beneficial depending on the stage of the disease.

For all stages of kidney disease, water should always be available.

Kidney removal is not an option because 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 kidney disease is possible.

Because CKD affects a cat's hydration, if an additional disease or illness interferes with hydration, it's important to treat it promptly with IV fluids.

Recovery and Management of Chronic Kidney Disease in Cats

Chronic kidney disease in cats is not curable and is often progressive, although the timeline can vary. Cats diagnosed early can benefit from nutritional management and more frequent veterinary attention, including more frequent checkups and blood work.

Management of Stages I and II

Cats in stages I and II may be monitored for further progression of signs. 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.

Management of Stages III and IV

Cats in stages III and IV often require more medical and dietary assistance, which may include:

• Erythropoietin injections: 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 medications: May be given to cats with a poor appetite, vomiting, or nausea.
• Fluids: Fluids given either intravenously or underneath the skin can help with dehydration. Your veterinarian can show you how to administer these fluids at home.