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Vet caring for a cat with kidney failure at Bond Vet

Kidney Failure in Cats: Symptoms, Treatment & More

Kidney failure—or renal failure—is a condition in which kidney function declines. This can make a cat ill and eventually cause death. Unfortunately, it’s common in cats (much more common than it is in dogs)—especially in older cats, although it may affect cats of any age.

The good news is, many cats live happily for years with kidney dysfunction, especially if the disease is caught early. Here are some important things to know about recognizing, diagnosing, and treating kidney failure in felines.

What Is Renal Failure in Cats?

A cat’s kidneys perform many important functions. They remove waste products and toxins from the bloodstream, conserve and balance water in the body, produce urine, regulate the levels of certain electrolytes and minerals, help control blood pressure, and release hormones for red blood cell production.

Amazingly, the kidneys can do their job even with significant disease or damage. This means that often, once evidence of kidney failure appears, 75% or more of kidney tissue (from both kidneys combined) isn’t working properly.

Decreased kidney function results in many imbalances in the body, along with build up of waste products in the blood—all of which can make a kitty very sick. Severe kidney disease can cause death.

What Causes Kidney Failure in Cats?

There are many possible causes of kidney failure in cats, including…

  • Gradual “wearing out” of the kidneys over time, with old age.

  • Congenital or hereditary kidney abnormalities. One example is polycystic kidney disease (PKD), a condition that occurs primarily in Persian cats and other long-haired cat breeds.

  • Diseases of the urinary tract or kidneys. A few examples include…

    • Urethral obstruction or urinary blockage, which causes backup of urine into the kidneys. This is most common in young male cats.

    • Pyelonephritis, or bacterial infection of the kidneys.

    • Kidney stones.

    • Amyloidosis, a condition most common in Abyssinian cats in which a specific type of protein called amyloid accumulates in the kidneys.

  • Certain infections, such as FIP (feline infectious peritonitis).

  • Poisons and toxins. Common culprits include:

    • Lily plants (all parts of the plant, including the leaves, flowers, stems, and even the pollen).

    • Antifreeze (ethylene glycol).

    • Grapes and raisins.

    • Some medications (example: Ibuprofen).

    • Rat poison.

  • Certain types of cancer.

  • Anything that limits blood flow to the kidney or causes shock, such as severe dehydration, heatstroke, very low blood pressure, traumatic injuries, or snake/insect bites.

Types of Kidney Failure in Cats

This differentiation is made because it affects prognosis and treatment plans. Types of kidney failure include…

Acute kidney failure

Acute renal failure, also called acute kidney injury (AKI), happens suddenly due to an underlying cause (toxins, urinary obstructions, etc.). Cats often become very ill very quickly. But even if your cat seems fine and you know they’ve ingested something toxic, take them for veterinary care because early treatment gives them a better chance of recovering.

AKI is serious and unfortunately, many cats die even with treatment. But prompt veterinary care gives a cat their best chance—and some cats make a full recovery! Others might survive but have damage to the kidneys that leads to chronic kidney failure. 

Chronic kidney failure

Chronic renal failure means the disease progresses over months to years. Most often, the cause is unknown and thought to be natural wearing out of the kidneys with advanced age (similar to how aging joints don’t work as well). Chronic kidney failure is most common in senior cats over 7-10 years of age.

Unfortunately, there is no cure for chronic kidney disease in cats. However, since the disease often progresses slowly, early intervention can help many cats live a happy life for several years.

Stages of Kidney Failure in Cats

Many vets use the IRIS (International Renal Interest Society) classification system. It helps provide clarity and standard treatment guidelines. Based on laboratory tests and blood pressure measurements, this system classifies a pet into stages from 1-4. Stage 1 is the earliest, generally associated with the least amount of illness. Stage 4 represents more severe disease.

When end-stage renal failure occurs, a cat might become ill, refuse food, and no longer feel better with treatments. This is when many cat owners consider euthanasia.

Signs and Symptoms of Kidney Failure in Cats

The following are some of the most common signs of kidney failure in cats, depending on the severity of their condition…

  • Increased urination and increased thirst in the early stages. In the late stages, a cat might produce less urine or none at all.

  • Decreased appetite or anorexia.

  • Digestive problems, like nausea, vomiting, or diarrhea.

  • Lethargy.

  • Weight loss or muscle loss.

  • Halitosis (bad breath).

  • Dehydration.

  • Behavior changes like hiding.

  • Poor hair coat or decreased self-grooming.

  • Ulcers in the mouth or stomach.

  • Particularly in acute kidney injury, a cat might arch their back or seem painful when you touch their belly or back, due to kidney swelling and pain.

Diagnosis and Treatment Options for Feline Kidney Failure

Most cats do not show any symptoms of kidney failure until the disease becomes more severe! Routine blood tests and urine checks are important, especially as a cat gets older—to help detect and treat kidney disease earlier.

Blood work often shows elevations in two kidney related values, blood urea nitrogen (BUN) and creatinine. Depending how advanced the condition is, additional abnormalities (like electrolyte changes or anemia/low red blood cell count) might be present.

A urinalysis typically shows a low urine specific gravity, or inability to concentrate the urine. Urine becomes more dilute as the kidneys flush more water through to compensate for a weaker filtration ability. Urine might also show abnormalities like increased protein content.

Dilute urine, combined with elevated creatinine and BUN, is known as azotemia, and it can make a cat feel sick. But in the early stages of kidney dysfunction, general blood work might appear normal. For this reason, many veterinarians have added a newer blood test called SDMA, which can help identify kidney disease earlier.

Radiographs or ultrasound might be necessary, especially if the cause of the kidney disease is unknown. In some cases, additional tests, such as a kidney biopsy, may be recommended.

Treatment for kidney failure depends on a number of factors and your cat’s individual needs. Keeping in mind that specific therapies will be tailored to your individual kitty, here are some common components of a treatment plan…

  • Fluid therapy. This staple of kidney disease treatment keeps a cat hydrated and helps the kidneys flush toxins and waste products from the blood. It also aids in preventing constipation, which is common secondary to kidney disease related dehydration. 

  • Home treatment or hospitalization. Hospitalization is common for acute kidney failure. But even in chronic kidney failure, some pets benefit from IV fluids and hospital care as a jump start to their ongoing home therapies.

  • Correcting the underlying cause, if possible. For example, a urethral blockage must be corrected. And for some toxicities, induced vomiting can help rid the body of some of the toxic load.

  • Treating complications and uncomfortable symptoms of kidney disease. This might include…

    • Antinausea medications.

    • Appetite stimulants.

    • Antacids to prevent ulcers.

    • Correcting electrolyte imbalances (potassium decreases or excesses are common, depending on the stage of kidney failure) and mineral imbalances (calcium and phosphorus balance is a big concern).

    • Specialized supplements or medications for anemic pets, for red blood cell production.

    • Reducing hypertension and maintaining a normal blood pressure.

  • Special kidney-friendly diets. Prescription therapeutic diets help maintain kidney health and reduce symptoms. Common features include a lower protein content (less work for the kidneys and less protein-associated waste products in the blood) and lower phosphorus content. In some cases, canned food might be recommended to increase water intake.

  • Other treatments. While less common and not available everywhere, hemodialysis (using special equipment) or peritoneal dialysis (administering and then draining fluids through the abdomen) may be performed in some cats who can benefit from it. Some specialists in the country might be able to perform a kidney transplant, too. But it’s important to consider pros and cons in terms of a cat’s expected survival and quality of life after such procedures. They’re not right for every cat.

Prognosis for Cats with Kidney Failure

Prognosis depends on the individual cat, the specific details of their disease, and their response to medical treatments. Some cats can live happily for years, while others unfortunately succumb to kidney disease in weeks to months.

Your veterinarian can help develop a care plan based on your cat’s unique needs. In the early stages, this might simply include a diet change, occasional fluid therapy (pet owners can learn to administer fluids under the skin at home), and possibly a medication or supplement. 

Always check with your vet prior to giving anything to your cat, to make sure it’s safe and appropriate for your kitty! Also, keep up with recommended monitoring and lab tests, as your cat’s needs can change over time.

If you have any questions or concerns about your cat’s health, schedule a telehealth or in-clinic visit today! 


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