Kidney failure in cats, also known as renal failure, is a serious condition where the kidneys become too damaged to function properly. These vital organs are responsible for filtering waste, balancing hydration, producing essential hormones, and regulating blood pressure. When a cat’s kidneys lose over 75% of their function, noticeable changes can occur. While kidney failure is life-threatening, early diagnosis and appropriate management, including specialized therapeutic diets, can significantly extend a cat’s life and maintain their comfort. This condition requires careful attention from cat owners.
Types of Kidney Failure in Cats
Kidney failure in cats can manifest in two primary forms: acute and chronic.
Acute Kidney Failure (ARF)
Acute kidney failure occurs suddenly, developing within hours or days due to rapid damage, often caused by poisoning or fast-acting infections. While ARF can be fatal in about 50% of cases, cats that survive the initial insult may regain some kidney function with prompt treatment and supportive care. The outcome for cats with ARF is generally more favorable than for those with chronic kidney disease if they recover from the acute event.
Chronic Kidney Disease (CKD) and Chronic Kidney Failure
Chronic kidney disease (CKD) involves a gradual loss of kidney tissue over months or years. This progressive decline can stem from genetic factors, chronic infections, aging, cancer, or other underlying medical issues. Clinical signs typically emerge when approximately two-thirds of the kidney tissue is lost. As CKD advances, medical management becomes less effective, eventually leading to end-stage renal failure (ESRF), which is considered stage 4 of kidney disease.
Symptoms of Kidney Failure in Cats
The symptoms of kidney failure in cats can vary depending on whether the condition is acute or the final stages of CKD.
Acute kidney failure may present with symptoms such as:
- Sudden onset of illness
- Vomiting and diarrhea
- Lethargy and weakness
- Dehydration
- Pain or discomfort
End-stage kidney failure associated with chronic kidney disease often includes:
- Anorexia or refusal to eat
- Vomiting
- Significant weight loss
- Lethargy and excessive sleepiness
- Dehydration
- Confusion, pacing, or restlessness
- Behavioral changes, such as becoming withdrawn or irritable
- Inappropriate urination or defecation
- Increased thirst and urination
- An ammonia-like odor to the breath
- Seizures
- Decreasing body temperature
- A greasy, unkempt, and thin hair coat
Stages of Kidney Failure in Cats
Veterinarians often categorize kidney failure in cats into stages based on laboratory values (like creatinine and blood urea nitrogen – BUN, which indicate waste accumulation in the blood) and observed symptoms.
Stage 1
In this initial stage, the kidneys are damaged, but there are no significant waste products accumulating in the blood (no azotemia). Cats typically show no clinical signs or symptoms, making diagnosis very rare at this point. This stage offers the highest chance of successful treatment.
Stage 2
Kidney function begins to decline, leading to mild azotemia detected in blood work. The kidneys’ ability to concentrate urine diminishes, resulting in more diluted urine, which can be identified by a decreased urine specific gravity (USG) on urinalysis. Some cats may start to exhibit increased thirst and urination (polyuria and polydipsia – PU/PD).
Stage 3
The kidneys’ filtering capacity continues to decrease, and azotemia worsens as waste products build up in the blood. Cats in this stage typically begin to show noticeable clinical signs.
Stage 4
This is the final and most severe stage. The kidneys’ ability to filter waste is severely compromised, leading to a toxic buildup in the blood that affects other organs. Cats at this stage often appear very ill. Bone health can be compromised, leading to a risk of fractures, and teeth may even fall out in younger cats due to brittle jawbones.
Causes of Kidney Failure in Cats
Both acute and chronic kidney failure can have various underlying causes.
Acute kidney failure can be triggered by:
- Toxins: Ingesting substances like antifreeze, certain plants (e.g., lilies), certain medications (e.g., NSAIDs), heavy metals, or contaminated food.
- Underlying medical issues: Including urethral obstructions, low blood pressure, clotting disorders, heart disease, kidney infections (pyelonephritis), parasitic infections, tick-borne diseases, feline infectious peritonitis (FIP), severe trauma, or anaphylactic shock.
Chronic kidney disease (CKD), which progresses to kidney failure, can be influenced by:
- Age: It’s common in older cats.
- Genetics: Certain breeds are predisposed, such as Persians, Abyssinians, Siamese, and Russian Blues.
- Tumors and cancer: Lymphoma is a common example.
- Viral infections: Feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV).
- Chronic infections: Such as slow-developing kidney infections.
- Genetic disorders: Polycystic kidney disease or amyloidosis.
- Immune-mediated disorders.
- Previous acute kidney injuries that didn’t fully resolve.
- Underlying medical conditions: Like hyperthyroidism.
- Certain medications.
- Not breeding affected cats: Genetic predispositions highlight the importance of responsible breeding practices.
Diagnosis of Kidney Failure in Cats by Veterinarians
Veterinarians diagnose kidney failure through a combination of physical examinations, blood work, urinalysis, and imaging techniques such as X-rays and ultrasounds. Key diagnostic indicators include:
- Anemia: A decrease in red blood cells.
- Elevated BUN and creatinine: Indicating poor kidney filtration.
- Abnormal hydration levels: Assessed by electrolyte concentrations.
- Urine abnormalities: Dilute urine or signs of infection.
- Blood pressure: Both high and low blood pressure can be indicative.
- Kidney size: Kidneys may appear enlarged or smaller than normal on imaging.
Treatment for Kidney Failure in Cats
Treatment for kidney failure in cats focuses on managing the disease and improving the cat’s quality of life. Options are limited, especially in end-stage cases, but can include:
- Specialized Diets: Renal support diets, low in protein and phosphorus, and low in sodium, are crucial. These diets help reduce waste buildup, support hydration, and often contain beneficial amino acids and omega-3 fatty acids. Veterinary-prescribed diets like Royal Canin Renal Support, Hill’s k/d, and Blue Buffalo Natural Veterinary Diet Kidney + Mobility Support are highly recommended. These diets can double the lifespan of cats with CKD compared to those on regular maintenance diets.
- Medications: Anti-nausea medications (e.g., Cerenia) and antacids (e.g., famotidine) help manage stomach upset. Appetite stimulants (like mirtazipine) and blood pressure medications may also be prescribed.
- Supplements: Products like AminAvast and VetriScience Renal Essentials can help decrease azotemia and support kidney function. Purina Hydra Care is a supplement designed to encourage water intake, promoting kidney health. Always consult your veterinarian before administering any supplements.
- Fluid Therapy: Hospitalization with intravenous (IV) fluids can help stabilize cats, especially in acute cases or during acute crises in CKD.
- Feeding Tubes: In severe cases, a feeding tube may be necessary to ensure adequate nutrition.
- Hemodialysis: While not curative, hemodialysis can improve quality of life for some cats, though it is expensive and requires specialized facilities.
- Kidney Transplant: This is an experimental option requiring specialist involvement.
- Humane Euthanasia: When a cat’s quality of life can no longer be maintained, humane euthanasia is a compassionate option, and veterinarians can guide owners through this difficult decision.
Recovery and Management of Kidney Failure in Cats
The prognosis for cats with kidney failure is generally poor, especially in advanced stages. Management is lifelong, and at some point, medical interventions may no longer be sufficient to keep a cat comfortable. End-of-life planning and discussions about quality of life with a veterinarian are essential.
Preventing Kidney Failure in Cats
While many causes of kidney failure cannot be prevented, some instances are avoidable:
- Toxin Avoidance: Keep antifreeze, lilies, and all medications and household cleaners out of reach.
- Responsible Breeding: Avoid breeding cats with known genetic predispositions to kidney disease.
Kidney Failure in Cats FAQs
Is kidney failure in cats painful?
Acute kidney failure can cause pain due to kidney enlargement and abdominal distention. Urinary issues associated with kidney disease can also be painful. Chronic kidney disease, developing gradually, is typically less painful, although discomfort can increase as the disease progresses.
What is the life expectancy of cats with kidney failure?
Cats in early stages (1 and 2) of kidney failure can live for many years with appropriate treatment, including diet, medication, and regular veterinary care. Cats in advanced stages (3 and 4) have a significantly shorter life expectancy, which depends heavily on their symptoms and response to aggressive treatment. Humane euthanasia is often considered for cats in these later stages.
What are the early signs of kidney failure in cats?
The earliest signs of kidney disease in cats are often increased thirst (polydipsia – PD) and increased urination (polyuria – PU). This can lead to a cat drinking from unusual places like toilets or sinks and may result in accidents outside the litter box due to increased frequency or volume of urination.
