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Pet Health

Understanding Kidney Failure in Cats: A Comprehensive Guide

Kidney failure is a condition that occurs when a cat's kidneys are unable to perform their essential functions effectively; including filtering waste products from the blood.

Dr. Bethany Hsia

July 26, 2023

As pet parents, we all want the best for our feline friends. But sometimes, our furry family members face health challenges that can be overwhelming. One such condition is kidney failure in cats. In this comprehensive guide, we aim to demystify the subject, arming you with the knowledge you need to understand this complex health issue. By reading this article, you'll gain insights into the types, causes, symptoms, and treatment options for kidney failure in cats. Let's embark on this learning journey together.

Unveiling the Mystery: What is Kidney Failure in Cats?

Kidney failure, also known as renal failure or renal insufficiency, is a condition that occurs when a cat's kidneys are unable to perform their essential functions effectively. These functions include filtering waste products from the blood, controlling blood pressure, maintaining electrolyte and hydration balance, managing calcium, and producing red blood cells. With so many important jobs, it’s clear that sufficient kidney function is vital to overall health; in fact, kidney failure can be life-threatening.

The kidneys live in the abdomen up near the cat’s spine, with one on the left and one on the right. These two bean shaped organs are made up of millions of tiny filtration units called nephrons. Blood vessels connect to the “dimple” area of the kidney to bring blood to nourish the organ as well as bring blood to be filtered and send the filtered blood back to the rest of the circulation. This area of the kidney also houses the attachment of the ureter, a small tube which connects the kidney to the bladder so urine may be stored before being expelled from the body.

Kidney Failure in Cats

Decoding the Disease: Types of Kidney Disease in Cats

There are two primary types of kidney failure that affect cats: Acute Renal Failure (ARF) and Chronic Kidney Disease (CKD). ARF is a sudden condition that can potentially be corrected with prompt intervention. Meanwhile CKD is a slow-developing disease, often due to underlying conditions and may only become noticeable when the kidney damage is advanced.

CKD can often be managed but will not be cured. Cats may experience both forms of renal disease concurrently either as an acute injury to a CKD sufferer or the development of CKD as a result of extreme ARF. CKD can further be described in Stages I-IV as discussed later.

Identifying the Culprits: Common Causes of Kidney Failure in Cats

The causes of kidney failure in cats can be numerous and varied depending on whether they lead to acute or chronic renal insufficiency. ARF may be due to toxin exposures, trauma, infection, organ failure, blockages, and severe hypotension (low blood pressure). In contrast, CKD arises from underlying issues such as immune-mediated diseases, hypertension, clotting disorders, cancers like lymphoma, or inherited conditions such as Polycystic Kidney Disease and Amyloidosis. As previously mentioned, CKD can also result from severe ARF. It's worth noting that despite thorough testing, the root cause of kidney disease might remain elusive.

Factoring in Feline Age: Relevance of Cat's Age in Kidney Failure

The age at which kidney disease appears can vary widely depending on the cause. CKD tends to be more common in older cats due to the natural degradation of the kidney’s nephrons over time; of which a normal cat has millions. Additionally, a cat can function normally with just ⅓ of normal kidney tissue remaining, further delaying signs of CKD. On the other hand, ARF affects cats of any age, as it often results from external factors such as toxins or trauma. Regardless of age, regular check-ups with the vet are essential for early diagnosis and intervention.

Recognizing the Red Flags: Common Symptoms of Kidney Disease in Cats

Timely detection can significantly improve the outcome of a beloved feline suffering from kidney failure. However, symptoms of kidney disease in cats can be subtle and sometimes go unnoticed or thought to be the result of other conditions. Symptoms vary depending on the severity of disease and begin with increased thirst and urination.

Other signs include weight loss, lack of appetite, bad breath, lethargy, weakness, unkempt coat, and nausea due to toxins building up in the bloodstream (uremia). ARF may involve greater signs of physical discomfort such as an arched back or a stiff-legged gait, due to a rapid onset of kidney pain.

Deciphering the Diagnosis: Diagnosing Kidney Disease in Cats

Only a veterinarian can diagnose kidney disease, so be sure to bring your kitty in for an evaluation as soon as you notice anything wrong. If your veterinarian suspects renal disease they will likely perform blood tests and urinalysis, in addition to a comprehensive physical exam and medical history. They may also request imaging studies such as X-rays or ultrasound, to get a clear understanding of your cat's kidney health.

Blood tests are primarily used to determine the levels of waste products like blood urea nitrogen (BUN) and creatinine, when a patient shows elevations in these markers they are said to have azotemia. In some cases, measuring a different waste product of protein metabolism known as symmetric dimethyl arginine (SDMA) can help to detect kidney disease earlier. Other important blood tests to determine the extent of kidney disease include checking the values of electrolytes, phosphorus, red blood cells, and proteins in the blood.

Examination of the urine is crucial to the diagnosis and monitoring of kidney disease. A main function of the kidney is to save water by concentrating the urine and to see that toxins leave while important blood components stay. Urinalysis gives crucial information about the concentration, pH, and presence of proteins, blood cells, bacteria, and other cells in the urine. Further information can be gathered from urine in the form of tests that look at the ratio of protein to creatinine (UPC) in the urine sample and test for bacterial growth (Urine Culture).

Evaluating blood pressure is an important piece of understanding the overall health of a cat and is important to the clinical picture of kidney disease as it can both cause and contribute to renal damage. Evaluating blood pressure can be tricky in cats, especially when the patient is stressed out. If possible it is recommended to capture “baseline” blood pressure readings when cats visit the vet for wellness appointments.

Understanding the Stages: Stages of Kidney Disease in Cats

Once diagnosed, your veterinarian will classify chronic kidney disease into one of four stages based on severity as described by the International Renal Interest Society (IRIS). It's crucial to note that disease progression varies among cats.The first stage involves mild renal insufficiency, where there are some elevations in blood creatinine and SDMA.

In Stage I cats do not usually display outward signs of illness. By the time your cat reaches Stage II, the loss has increased showing higher levels of protein waste products and some clinical signs may be present. In the third stage, renal insufficiency has progressed to moderate renal failure, accompanied by continued elevations in toxins and more dramatic symptoms, cats in Stage III often appear quite ill. Stage IV renal failure has become severe, marking the end-stage of kidney disease. These cats often present in crisis.

IRIS also describes a grading scale for Acute Kidney Injury (AKI). Similar to the CKD scale, the AKI scale is categorized into stages (I-V) based on the levels of creatinine in the blood and the clinical signs the cat is displaying. Stages I-II represent absent or mild elevations in creatinine while Stages III, IV, and V represent progressively increasing creatinine levels and symptoms.

Treatment Strategies

Medications for Cats with Kidney Disease

When it comes to effectively treating cat kidney disease, the first step is stabilizing the patient. How this looks will vary, whether your cat is presenting with stage IV renal disease or Stages I or II without outward signs of illness, your veterinarian will tailor their care to the pet’s needs. Very sick cats will need to be hospitalized for close monitoring and any necessary adjustments to the plan as treatment progresses.

Once the cat is stable, your veterinarian will further investigate the cause of your cat’s renal injury as well as any concurrent diseases (comorbidities). Treatment directed at the underlying cause may include aggressive antibiotics, anti-parasitics, immunosuppressants, “blood thinners,” or cancer fighting treatments such as chemotherapy.

Depending on the extent and cause of renal damage, your cat may be able to recover kidney function and return to normal. For cats with significant injury, or damage caused by a progressive condition, the goal is to slow further loss of kidney function and support the remaining healthy tissue. The medications your veterinarian selects will be targeted at this goal as well as managing any symptoms to provide your cat with quality of life. Such medications may include those to control high blood pressure, treat anemia, reduce nausea, correct imbalances in potassium and phosphorus, and manage other symptoms.

Hydrating for Health: Fluid Therapy for Cats with Kidney Disease

Keeping a cat adequately hydrated is a crucial element in managing kidney disease.The kidney is responsible for removing unwanted chemicals from the blood and conserving water, when it isn’t up to the task toxins buildup in the bloodstream and excess water is lost in the urine. Fluid therapy is a first line of defense when correcting the built up toxins and correcting dehydration, a process known as diuresis.

In-patient treatment will likely include intravenous fluids. This method of rehydration is direct and effective for correcting imbalances in electrolytes and maintaining proper blood pressure in hypotensive (low blood pressure) cats. Large volumes of fluids can be given in a relatively short period via intravenous therapy and can be easily adjusted to deliver more or less as needed.

Out-patients may receive fluid therapy via subcutaneous injection, wherein the proper fluids are injected under the cat's skin and slowly absorbed into the tissues. This procedure can be used to supplement fluids and avoid or correct mild dehydration. The procedure is quick and can usually be done as a technician appointment or you can be taught how to do it yourself at home with the supplies provided by your veterinarian. However, subcutaneous fluids are not useful for sick cats as they aren’t sufficient to flush out toxins nor impact blood pressure.

Dietary Changes for Cats with Kidney Disease

A significant part of managing kidney disease is dietary changes. Nutrition plays a vital role in how well your cat can combat the disease. Recall that the nephrons of the kidney act as filters. Simply put, part of their job is to “catch” and keep certain proteins and potassium while allowing other BUN, creatinine, and other metabolites to pass in the urine.

A diet low in protein will result in less byproducts from protein breakdown such as BUN and creatinine, this will make the job of the kidney easier in excreting them. Kidney friendly diets also feature lower phosphorus content preventing it’s buildup in the system and higher levels of potassium to supplement losses.

As previously discussed, maintaining hydration is crucial for the cat with kidney disease. Offering your feline friend a wet food kidney friendly diet can help increase their water intake. Any changes to your cat’s diet should be a slow, gradual process under the guidance of your vet.

When Surgery is an Option: Considerations for Surgery

In some cases, surgery might be considered as an option for treating kidney disease in cats. This route is typically pursued when there are complications that need to be addressed, such as kidney stones or tumors.

Additionally, surgery may be pursued when transplant is a viable option. Feline kidney transplants are only performed in specialty hospitals and not widely available at this time. Candidates for kidney transplant are otherwise healthy, this is not an option reserved for when all other treatments have failed.

As with any surgical procedure, it's important to have a detailed conversation with your vet about your pet's condition, the potential benefits, and risks associated with the surgical options.

Dialysis in Cats: Possibilities for Cleaning the Blood

Dialysis is a process of artificially cleaning the blood and not a word often heard in veterinary medicine. Two types of dialysis exist: hemodialysis and peritoneal dialysis. In each procedure a membrane separates the blood and toxins are attracted to the “waste” side. When most people think of dialysis they picture blood being filtered through an external machine and placed back into the patient.

This process requires the patient to sit calm and still for several hours, which is one hurdle for veterinary patients. Similar to transplant surgery, dialysis is performed at a specialty care facility and not meant as a last resort treatment. Speak with your veterinarian for more information and referrals to tertiary care facilities.

Exploring Alternatives: Alternative Treatments and Holistic Approaches

Alongside traditional treatments, some pet owners opt to explore alternative treatments and holistic approaches to manage their cat's kidney disease. These may include acupuncture, herbal remedies, or homeopathy.

Holistic approaches focus on improving the cat's overall well-being, aiming to boost their immune system and maintain their body's balance. Keep in mind that while some of these methods can help manage symptoms or improve quality of life, they should not replace medical treatments unless advised by a veterinarian. Always discuss any alternative treatments with your vet to ensure they're safe and won't interfere with other treatments your cat is receiving. Managing kidney disease in cats is complicated, but it’s possible with the right care and attention.

Managing Life with Chronic Kidney Disease: Living and Management of Ongoing Kidney Disease in Cats

Dealing with a chronic disease like kidney failure in a beloved pet can be a winding journey with ups and downs. At CodaPet, we understand the complexity this situation entails. Don't lose heart. By applying appropriate care measures, your feline friend can still enjoy a comfortable life despite having chronic kidney disease. Let’s look at the supportive measures you can take at home before reviewing the importance of diet.

Creating a Comforting Environment: Making Modifications at Home

Home modifications aim to provide a stress-free environment for your cat, lessening the physical strain on their already taxed kidneys. Ensure hygiene by keeping the litter box clean and free of odor. This helps encourage frequent urination, aiding the excretion of toxins from your cat's body. Providing soft bedding and easily accessible food and water dishes can make your cat's day-to-day life less strenuous.

Cats with kidney disease may struggle to maintain a stable body temperature. A warm, draft-free environment can significantly help in this regard. With a bit of effort, these tweaks around your home can greatly improve the quality of life for your furry companion dealing with kidney disease.

Staying Hydrated: Proper Hydration and its Importance

As we’ve already noted, cats with kidney disease often struggle with dehydration due to the kidneys' inability to conserve water. This can lead to increased urination, inevitably causing your cat to become dehydrated. To combat this, keep easy-to-reach water bowls around your home. Many commercially available cat “fountains” are designed for this purpose.

Some pet parents have found that leaving a faucet on at a small trickle works well for their pet. Additionally, flavoring the water with a tiny bit of tuna juice can encourage your cat to drink more. As we have mentioned, wet food options are a good way of introducing more fluids into your cat's diet and your veterinarian may recommend giving subcutaneous fluid at home, especially in the case of cats with advanced kidney disease.

Keeping Active: Activities and Exercises for Cats with Kidney Disease

Regular exercise is beneficial for cats with kidney disease, promoting better blood circulation and an overall healthy lifestyle. However, keep in mind that cats with kidney disease might have decreased energy levels. Allow your cat to lead the way when it comes to the intensity and frequency of physical activities. Simple activities like gentle play with toys, or even grooming can provide much-needed physical stimulation. Try to avoid stressful situations and remember that cats require plenty of safe places to find respite as needed.

Reviewing Feeding for Health: Reiterating the Importance of Managing Your Cat's Diet

The significance of dietary control cannot be overstated in managing kidney disease. Changes in diet have a direct effect on the progression of this illness. Provide a diet low in protein and phosphorus to prevent the accumulation of waste products in the blood. It's known that these substances stress the kidneys, accelerating disease progression. Also, opt for low sodium options to prevent hypertension, a common occurrence in cats with kidney disease.

It's wise to transition to these dietary changes gently, instead of a sudden switch which may cause refusal to eat or gastrointestinal distress. Remember that a diet must be balanced to maintain your cat's overall health and not just manage kidney disease. Pet owners are advised to consult their veterinarians before making any significant changes to the diet.

Preventive Measures: Routine Veterinary Checks for Early Detection

Regular veterinary checks are essential in diagnosing the early stages of kidney disease in cats, before additional problems arise. Chronic kidney disease in cats is often a silent affliction, showing no visible signs until it has significantly progressed. Therefore, vigilance in monitoring your feline friend's health through routine veterinary checks is critical. Such checks usually encompass a combination of physical examination, blood tests, and urine analysis.

Blood tests analyze the levels of waste products, such as blood urea nitrogen (BUN) and creatinine. Electrolyte levels, phosphorus, red blood cells, and proteins are also tested to get a comprehensive view of your pet's renal health. One significant addition to these tests in recent years has been the measurement of symmetric dimethyl arginine (SDMA). SDMA is a waste product of protein metabolism which has proved useful in detecting kidney disease early on cats, often before elevations in the other markers.

Urinalysis, on the other hand, helps determine the concentration, pH, and presence of proteins, blood cells, bacteria, and other cells in your cat's urine. Given the kidney's crucial role in urine production, changes in the constituents of the urine can help characterize kidney related issues and aid in determining the level of severity.

Keeping a regular check on your cat's blood pressure is also advisable, as hypertension can both result from and exacerbate the condition. Regularly monitoring your pet's health with the help of a trusted veterinarian will help catch kidney disease early, increasing chances of successful treatment and subsequently a healthier and happier life for your beloved pet.

Genetics at Play: Understanding Genetic Predisposition

Genetic predisposition plays a role in the susceptibility of cats to kidney disease. Certain breeds, such as Persians, Abyssinians, and Siamese cats, have been found to have a higher likelihood of developing particular types of kidney diseases due to inherited genetic factors.

In the case of Polycystic Kidney Disease (PKD), some cats are born with small cysts in their kidneys that increase in size over time, impacting kidney function. PKD is most common in Persian and Persian cross cats and is genetically inherited. Another genetic disease that breeds such as Abyssinians and Siamese are particularly prone to is Amyloidosis, where an anomalous protein, amyloid, gets deposited in the kidneys resulting in kidney dysfunction.

If you have or are considering one of these cats it is important to ask whether breeders test for these diseases;if your feline friend is at risk, ensure regular screening by your veterinarian for signs of kidney stress.

Beware of Risks: Raising Awareness about Risk Factors

In addition to genetic factors, several other risk factors can increase a cat's likelihood of developing kidney disease. Aging is one such factor. Just like in humans, a cat's organs can start to deteriorate with age, making older cats particularly susceptible to kidney disease.

Exposure to certain toxins can also lead to acute kidney injury. Some plants, such as lilies, and human medications like Ibuprofen, can be toxic to cats and can cause sudden kidney failure if ingested. Other underlying conditions like infections, blockages in the urinary tract, high blood pressure, and certain medications can all contribute to the development of kidney disease. Therefore, being vigilant about these risk factors and working towards minimizing them can aid significantly in preventing kidney disease in your furry friends.

While the term kidney failure can sound daunting, you are not alone in its management. Being informed, staying vigilant, and having an early detection plan in place can go a long way as you and your cat’s veterinarian advocate for your feline friend. Following their guidelines can help your beloved pet lead a comfortable and fulfilling life, despite their diagnosis.

This is not intended as medical advice nor for diagnostic purposes. Consult your veterinarian with any questions.



Dr. Bethany graduated from the University of Illinois College of Veterinary Medicine in 2010. After graduation, she moved west. Dr. Bethany spent a year at a small animal exclusive practice in Washington state, where she was first introduced to in-home euthanasia.  Read More