Kidney failure is a serious health condition in cats, affecting their ability to filter waste and maintain vital bodily functions. Understanding this condition is crucial for cat owners to ensure their feline companions receive the best possible care. Kidneys play a multifaceted role in a cat’s body, acting as filters to remove waste products through urine. They are also essential for maintaining hydration by balancing water and electrolytes, producing hormones vital for red blood cell production, and regulating blood pressure. Furthermore, kidneys contribute to the activation of vitamin D, making it usable by the body. Just like humans, cats are born with two kidneys situated in their abdomen. When these organs become significantly damaged, kidney failure occurs, preventing them from functioning effectively. Often, kidney failure is a consequence of chronic kidney disease (CKD), where kidney function gradually deteriorates over time. Alarmingly, more than 75% of kidney function can be lost before standard blood tests reveal abnormalities, such as elevated creatinine levels. Kidney Failure In Cats is a life-threatening condition with limited treatment options once it reaches an advanced stage. Therefore, it is paramount for pet owners to have open discussions with their veterinarians about their cat’s prognosis, closely monitor their cat’s quality of life, and consider humane euthanasia when necessary to prevent suffering.
Types of Kidney Failure in Cats
Kidney failure in cats is broadly categorized into two main types: acute and chronic.
Acute Kidney Failure in Cats
Acute kidney failure, also known as acute renal failure (ARF), is characterized by a sudden and rapid decline in kidney function, typically occurring within hours or days. This abrupt damage is often triggered by exposure to toxins or a swift infection. Cats suffering from ARF may have a chance to regain some kidney function with prompt and appropriate treatment, supportive care, and sufficient time for recovery, depending on the underlying cause of the acute failure. However, despite medical intervention, acute renal failure remains a grave condition, with approximately 50% of affected cats succumbing to the illness. Interestingly, cats that survive the initial acute kidney failure episode generally have a more favorable long-term outlook compared to those with chronic kidney disease (CKD).
Chronic Kidney Failure in Cats
Chronic kidney failure, or chronic kidney disease (CKD), is a progressive condition that ultimately leads to end-stage renal failure (ESRF), also known as stage 4 kidney disease. CKD involves a gradual and irreversible loss of kidney tissue occurring over months (defined as longer than 2 months) or even years. This slow deterioration is often attributed to underlying factors such as genetic predispositions, persistent infections, the natural aging process, cancerous growths, or other pre-existing medical conditions. Clinical signs of chronic kidney disease typically become noticeable only after about two-thirds of the kidney tissue has been irreparably damaged. As CKD advances, medical management becomes increasingly ineffective in supporting the kidneys’ essential functions.
Symptoms of Kidney Failure in Cats
The clinical signs of kidney failure in cats can vary slightly depending on whether the condition is acute or represents the final stages of chronic kidney disease.
In acute kidney failure, cat owners may observe the following symptoms:
For end-stage kidney failure associated with chronic kidney disease, the symptoms include:
- Anorexia or complete refusal to eat
- Vomiting
- Noticeable weight loss
- Lethargy and excessive sleepiness
- Dehydration
- Confusion, possibly indicated by pacing and restlessness
- Behavioral changes such as becoming withdrawn or showing increased irritability
- Loss of bladder control leading to uncontrolled urination or defecation
- Increased thirst and consequently drinking more water than normal
- Breath with an ammonia-like odor
- Seizures
- Decreased body temperature
- Poor coat condition, appearing greasy, unkempt, and thin
Stages of Kidney Failure in Cats
The staging of kidney failure in cats is determined by laboratory values obtained from blood and urine tests, combined with the clinical symptoms exhibited by the cat. Understanding these stages helps in tailoring treatment and managing expectations.
Stage 1 Kidney Failure in Cats
In stage 1 kidney failure, the kidneys are damaged, but azotemia is not yet present. Azotemia refers to the buildup of waste products in the blood, indicated by elevated creatinine and blood urea nitrogen (BUN) levels. Cats in stage 1 typically show no outward clinical signs or symptoms. This initial stage offers the highest chance of successful management and slowing disease progression. However, due to the absence of obvious symptoms and normal initial lab values, diagnosing kidney disease at stage 1 is exceedingly rare in cats.
Stage 2 Kidney Failure in Cats
Stage 2 kidney failure is marked by the kidneys beginning to lose their efficiency in filtering waste from the blood, and azotemia becomes detectable in blood work. The urine also starts to become more dilute, containing a higher proportion of water due to impaired kidney concentrating ability. A key indicator in urinalysis is a decrease in urine specific gravity (USG). While most cats in stage 2 still do not exhibit noticeable signs or symptoms, some may start to show increased thirst and urination (polyuria and polydipsia, PU/PD), characterized by more frequent urination and increased urine volume.
Stage 3 Kidney Failure in Cats
In stage 3 kidney failure, the kidneys’ filtering capacity continues to decline significantly. Azotemia worsens as waste products accumulate to higher concentrations in the bloodstream. Cats in this stage will begin to exhibit noticeable clinical signs of illness, reflecting the increasing burden of toxins in their system.
Stage 4 Kidney Failure in Cats
Stage 4 represents the final and most severe stage of kidney disease in cats. The kidneys’ ability to filter waste from the blood is critically impaired. The accumulation of toxins in the blood not only severely affects the kidneys but also starts to impact other organs throughout the body. Cats in stage 4 kidney failure become visibly and demonstrably ill. A concerning consequence of advanced kidney disease is the weakening of bones, making them soft and prone to fractures. Brittle jaw bones can even lead to teeth falling out, particularly in younger cats.
What Causes Kidney Failure in Cats?
Acute kidney failure in cats can stem from various causes, broadly categorized as toxin exposure or underlying medical conditions.
Exposure to toxins can occur through ingestion of:
Underlying medical issues that can lead to acute kidney failure include:
- Urethral obstructions (blockage of the urethra preventing urination)
- Hypotension (low blood pressure)
- Coagulation disorders (problems with blood clotting)
- Heart disease
- Pyelonephritis (kidney infection)
- Parasitic infections such as toxoplasmosis or kidney worms
- Tick-borne diseases
- Feline infectious peritonitis (FIP)
- Trauma or severe allergic reactions that lead to shock
Chronic kidney disease, in contrast, progresses gradually to end-stage renal failure and kidney failure. The timeframe for this progression varies greatly and is difficult to predict. CKD is highly prevalent in older cats (geriatric cats), and certain breeds are recognized to have a higher predisposition, including:
Other risk factors for chronic kidney disease include:
- Tumors and cancer, particularly lymphoma
- Feline-specific viral infections like feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV)
- Chronic pyelonephritis (slowly developing kidney infection)
- Inherited genetic disorders such as polycystic kidney disease or amyloidosis
- Immune-mediated disorders
- Previous episodes of acute renal failure or acute kidney injuries that did not fully resolve
- Underlying endocrine disorders such as hyperthyroidism
- Use of certain medications
How Veterinarians Diagnose Kidney Failure in Cats
Diagnosing acute renal failure in cats typically involves a combination of blood work, urine samples, and imaging techniques like X-rays and ultrasound. These diagnostic tools help veterinarians assess the extent of kidney damage and determine the most appropriate treatment plan. A thorough physical examination by the veterinarian is essential, including blood pressure measurement. Veterinarians look for key indicators such as:
- Anemia
- Elevated blood urea nitrogen (BUN) and creatinine levels
- Abnormal hydration status assessed through electrolyte concentrations (sodium, potassium, calcium, and phosphorus)
- Dilute urine or signs of urinary tract infection
- Hypertension (high blood pressure) or hypotension (low blood pressure)
- Changes in kidney size (enlarged or shrunken kidneys)
Kidney Failure in Cats Treatment
Treatment options for end-stage kidney failure in cats are limited and primarily focus on managing the symptoms and slowing disease progression. These management strategies include specialized diets, supplements, and anti-nausea medications. Remarkably, with diligent treatment, cats with as little as 5% kidney function remaining can still survive for a considerable period.
A cornerstone of treatment for cats with any form of kidney disease is a carefully formulated restricted diet. This diet helps manage hydration and minimize the buildup of toxins in the bloodstream. Prescription diets like Hill’s® k/d and Royal Canin® Renal Support are frequently recommended due to their specific formulations. These diets are characterized by reduced protein and phosphorus content to decrease azotemia, and low sodium levels to support hydration. They are also enriched with essential amino acids to maintain muscle mass and omega-3 fatty acids to promote kidney health and reduce inflammation. To address nausea, a common symptom of kidney disease, anti-nausea medications such as Cerenia® and antacids like famotidine are beneficial in controlling stomach upset. Depending on the individual cat’s symptoms, other medications may be necessary, including appetite stimulants (e.g., mirtazapine) and blood pressure medication.
Purina® Hydracare™ is a valuable supplement designed to encourage increased water intake in cats with kidney disease, thereby supporting kidney function. Other supplements like AminAvast® and VetriScience® Renal Essentials Feline can also be beneficial in reducing azotemia and promoting kidney health. It is crucial to consult with your veterinarian before administering any supplements to your cat to ensure safety and compatibility with their overall health status and treatment plan. In many cases, hospitalization with intravenous (IV) fluid therapy and the placement of a feeding tube may be necessary to stabilize a cat experiencing kidney failure. Some cats respond well to this intensive support and can return home for ongoing management of their kidney disease. For more advanced treatment, hemodialysis, a procedure to filter the cat’s blood artificially, is available. While hemodialysis cannot cure kidney failure, it can significantly improve a cat’s quality of life. However, it is a specialized treatment, and few veterinary clinics are equipped to offer hemodialysis. The cost is also substantial. Kidney transplantation is another experimental option, but it is not widely practiced in cats and requires evaluation by specialists to determine if a cat is a suitable candidate. When a cat is diagnosed with kidney failure, close collaboration with your veterinarian is essential to discuss prognosis, strategies for monitoring quality of life, and to address the sensitive topic of when humane euthanasia should be considered to prevent prolonged suffering.
Recovery and Management of Kidney Failure in Cats
The prognosis for cats with kidney failure is generally guarded to poor, particularly in advanced stages. Eventually, medical management may no longer be sufficient to maintain a comfortable quality of life for the cat, necessitating discussions with your veterinarian about end-of-life planning. This decision is emotionally challenging for pet owners. Your veterinarian can provide invaluable guidance in assessing your cat’s quality of life and help you prepare a compassionate plan, including considering humane euthanasia, especially for situations that may arise outside of regular veterinary clinic hours.
How to Prevent Kidney Failure in Cats
While many forms of kidney failure in cats are unfortunately not preventable, kidney failure due to toxin ingestion is largely avoidable. It is imperative to never bring lilies or bouquets containing lilies into a home with cats due to their extreme toxicity. All medications and cleaning products should be stored securely in closed containers and kept out of reach of cats. Limiting a cat’s access to garages and areas where chemicals like antifreeze are stored is also crucial. Since a significant proportion of kidney disease in cats has a genetic basis, responsible breeding practices are essential. Breeding affected cats should be avoided to reduce the incidence of hereditary kidney conditions.
Kidney Failure in Cats FAQs
Is kidney failure in cats painful?
Pain levels in cats with kidney failure can vary depending on the type and stage of the condition. Cats with acute kidney failure may experience pain due to kidney enlargement and abdominal distention. Urinary tract issues like obstructions or infections, which can contribute to kidney disease, are also painful. In contrast, chronic kidney disease often develops gradually over months or years and may be less overtly painful in its progression.
What is the life expectancy of cats with kidney failure?
The life expectancy for cats diagnosed with kidney failure varies widely depending on the stage at diagnosis and their response to treatment. Cats in the early stages, stage 1 and 2 kidney failure, can often live for many years with appropriate management. This typically includes a special diet, medications, supplements, and regular veterinary check-ups to monitor disease progression. Cats in later stages, stage 3 and 4 kidney failure, require more intensive treatment and management, often involving hospitalization. Their life expectancy is more variable and depends on symptom severity and treatment response. In many cases of stage 3 or 4 kidney disease, humane euthanasia is compassionately considered to alleviate suffering.
What are the early signs of kidney failure in cats?
The earliest signs of kidney disease in cats are often subtle and easily missed. Polydipsia and polyuria (PU/PD), increased thirst and urination, are among the most common initial indicators. Polyuria manifests as an increase in the frequency and volume of urination, which may lead to accidents outside the litter box. Polydipsia is characterized by excessive drinking, sometimes to the point of seeking water from unusual sources like toilets or sinks.
WRITTEN BY
Jamie Case, DVM
Veterinarian
Dr. Jamie Case graduated from the University of Missouri College of Veterinary Medicine in 2017, after receiving a Bachelor of Science…
