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What You Need to Know About Kidney Disease in Cats

Extreme thirst and frequent urination may be signs that your cat has kidney disease. Learn why regular veterinary care is key to discovering and managing the condition.
By Kristi Valentini Medically Reviewed by Jenna Stregowski, RVT Updated June 08, 2022 Medically Reviewed by Jenna Stregowski, RVT Advertisement Pin FB More Tweet Email Send Text Message Print
cat drinking tap with Feline Fine logo; referring to kidney disease in cats Credit: Sean Savery Photography / Getty

What Is Kidney Disease in Cats?

Kidney disease occurs when the kidneys lose some of their function. The kidneys' primary job is to filter waste and toxins out of the blood and into urine, but they also regulate mineral levels and trigger the production of red blood cells, which carry oxygen throughout the body. When the kidneys aren't performing well, harmful substances build up in blood. Cats with kidney disease can also develop anemia, or lack of red blood cells.

Kidney disease in cats is sometimes called kidney failure or renal failure. These terms are often used interchangeably, but it's considered more accurate to call it kidney disease or renal disease. The word renal means "relating to the kidneys."

Types of Kidney Disease in Cats

In cats, there are two types of kidney disease. Acute kidney disease comes on suddenly and is a short-term disease that is reversible in some cases. Chronic kidney disease (CKD) is a long-term illness that gets worse over time. CKD is sometimes called kidney insufficiency or renal insufficiency.

Acute kidney disease, sometimes called acute kidney injury, is fairly uncommon in cats. CKD, however, is more prevalent—especially in older cats. One study found the prevalence of CKD to jump from 13 percent in cats under 4 years old to 32 percent in cats 15 and older.

What Causes Kidney Disease in Cats?

Kidney disease is caused by kidney damage, and there are a number of ways this damage can happen.

"Acute cases usually happen when a cat eats something poisonous, like antifreeze or Easter lilies, or has an infection," says Erick Mears, DVM, DACVIM, medical director of BluePearl Pet Hospital in Tampa Bay, Fla. "But kidney disease in cats is mostly chronic. Previous infection, another disease, or an unknown cause may damage the kidneys."

Other potential causes of kidney injury include:

Trauma
Kidney stones
Certain medications
Diabetes
Cancer
Hereditary issues

Cats with acute kidney disease may eventually develop chronic kidney disease. When part of the kidney is damaged, the rest of the organ has to work harder to keep up with the body's demands. Eventually, this extra effort wears the kidneys out, and their function further decreases. This is why chronic kidney disease gets worse over time.

Signs of Kidney Disease in Cats

The signs of acute kidney disease come on suddenly, often beginning with a poor appetite and lethargy. Other signs depend on the cause of the kidney injury and the severity of the damage.

Though it's best to catch chronic kidney disease at an early stage, it's often hard for pet parents to spot the beginning signs, Mears says. After all, cats are masters at masking their weakness—it's a survival instinct. Your veterinarian is more likely to detect early-stage kidney disease through routine wellness testing. Urinalysis (a urine sample test) can show high protein levels, an indication of kidney problems. High blood pressure can be a red flag, too.

Chronic kidney disease usually occurs in older cats—only 10 percent of young kitties are affected. See your vet if you notice any of these symptoms:

Increased thirst
Frequent urination
Lethargy or low energy
Vomiting
Poor appetite
Weight loss
Dull and thinning fur
Mouth ulcers

RELATED: How Often to Take Your Kitten or Cat to the Vet

Stages of Feline Kidney Failure

Veterinarians often use a staging system created by the International Renal Interest Society (IRIS) to categorize the severity of chronic kidney disease in cats. Each stage corresponds to the severity of kidney damage, with stage one being the mildest and stage four the most advanced.

Your vet will evaluate blood test results to determine the stage of your cat's kidney disease. Staging information helps your vet give you a prognosis and advise the best treatments for your kitty.

Treatment for Kidney Disease in Cats

Some cases of acute kidney disease can be treated before the organs are permanently damaged. This requires intravenous fluid therapy to flush toxins out of the blood. Additional treatments depend on the original cause of the kidney injury. Most cats will need to be hospitalized for monitoring and treatment.

Chronic kidney disease has no cure, and damage isn't reversible. However, you can treat the symptoms to make your fur baby feel better. Veterinarians often recommend an approach that combines these elements:

Special Diet

One of the most important aspects of managing kidney disease in your cat is changing his diet. According to the Cornell Feline Health Center, these special diets are typically lower in protein, phosphorus, and sodium to reduce the amount of waste kidneys need to clean from the blood.

Your vet will suggest prescription food brands and formulas to try, and many vets recommend wet food to help keep cats well-hydrated. You may need to offer your cat a few different brands and formulas to figure out what he likes best. But no matter the brand, it's essential for your cat to keep eating to avoid weight loss.

Fluid Therapy

The kidneys use water from the bloodstream to filter out toxins and produce urine, but failing kidneys lose the ability to concentrate the urine and require more water to function. (This is why cats with kidney disease tend to drink a lot of water.) As kidney disease progresses, it becomes increasingly difficult for cats to drink enough water to stay hydrated and filter toxins out of the blood.

Fluid therapy provides extra hydration. Intravenous fluids may be given to cats at the hospital, but some benefit from subcutaneous (under the skin) fluid supplementation at home. Your veterinarian can show you how to do this and give you the right gear to do so.

Blood Pressure Medication

Kidney disease causes high blood pressure, which in turn creates more kidney damage. High blood pressure also impacts the heart and other vital organs. Luckily, this can be managed through oral medications.

Hormone Therapy

Healthy kidneys play a part in making erythropoietin, a hormone that kickstarts red blood cell production. As the kidneys start to fail, your cat's red blood cell level may drop too low (causing anemia). Because red blood cells carry oxygen, not having enough can make your cat extremely fatigued and weak.

"If your cat is anemic, starting hormone therapy can help them drink and eat more, which will make them feel better," Mears says.

Is Kidney Disease Painful?

Kidney disease does not typically cause pain, but it does cause overall discomfort. Managing symptoms is key to making sure your cat feels comfortable, so work with your vet to address any new concerns as they crop up. For example, cats with chronic kidney disease may feel nauseous and refuse to eat. You can ask your vet about ways to coax your kitty to eat her new food.

Your kitty also needs lots of water, as cats with kidney disease quickly become dehydrated. Make sure the water bowl is always full and consider placing multiple water bowls throughout your home for easy access. You can also offer a circulating water fountain, which may appeal to a cat who loves to lick from the faucet.

With a little extra effort, many cats can continue to live happy lives. "Cats can live for years with kidney disease," Mears says. "It really depends on whether they're in the earlier or later stages. But often they live for three to six years after diagnosis."

RELATED: 4 Simple Ways to Get Your Cat to Drink More Water

How to Prevent Kidney Failure in Cats

To avoid bouts of acute kidney disease, the most important things you can do is take steps to keep your cat healthy, such as taking your kitty to the vet once or twice a year.

For chronic kidney disease, take these four steps to maintain the overall health of your cat's kidneys:

Provide plenty of water to help the kidneys flush out toxins.
Clean the litter box regularly to encourage your cat to urinate.
Help your cat maintain a healthy weight to avoid diabetes, which can lead to kidney failure.
Visit your vet at least once a year for wellness checks, when the first signs of kidney disease are often found.

If you notice your cat drinking a ton of water, contact your vet. It could be a sign of kidney disease or another serious condition such as diabetes or hyperthyroidism. Catching a disease earlier is always better, and with help from your vet, your kitty could live comfortably with kidney disease for years to come.

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