Your Cat And Kidney Disease What You Need To Know

Kidney disease in cats is one of those things most of us don’t really think about until a vet says, “We’re seeing some changes in the kidneys.” If you share your home with a middle-aged or senior cat, it’s worth understanding now, because kidney problems are actually very common as cats get older. Some studies estimate that around 30–40% of cats over 10, and more than 80% of cats over 15, have chronic kidney disease.

So what are the kidneys actually doing all day long? In simple terms, they’re your cat’s built-in filters and balance keepers. They remove waste and toxins from the blood, make urine, help regulate fluids and electrolytes, help with blood pressure control, and even play a role in making red blood cells through a hormone called erythropoietin. When the kidneys start to fail, waste products and extra fluid build up in the body and your cat just doesn’t feel well.

Most of the time when we talk about kidney disease in cats, we’re talking about chronic kidney disease, or CKD. That means the kidneys are slowly losing function over months or years. There is also acute kidney injury, which comes on suddenly from things like toxins, severe dehydration, certain infections, or some medications. Acute problems can sometimes be reversed if treated immediately, while chronic disease is usually permanent and managed rather than cured.

Those signs don’t prove kidney disease on their own, but they are your cue to get your cat in for an exam and lab work. Your vet will usually start with blood tests and a urinalysis. Blood work looks at kidney values like creatinine, BUN, and SDMA, along with electrolytes and red blood cells. A urinalysis shows how well the kidneys are concentrating urine and whether there is protein or infection. Many vets also recommend checking blood pressure, because high blood pressure is common in cats with kidney disease and can make the damage worse.

Once kidney disease is confirmed, your vet may talk about “staging” it, often using the IRIS guidelines. Staging sounds scary, but it’s really just a way of describing how advanced the disease is so that treatment and follow-up can be tailored to your cat. Cats in the earliest stage may have only mild lab changes and feel mostly normal; cats in later stages have more obvious symptoms and need more intensive support. With early diagnosis and good management, many cats live comfortably for months to years after a kidney disease diagnosis.

The good news is that while we can’t usually “fix” chronic kidney disease, we can absolutely make a difference in how your cat feels and how long they stay comfortable. Treatment plans are customized, but they usually focus on four main goals: keeping your cat well hydrated, reducing the buildup of waste products, balancing minerals like phosphorus and potassium, and trying to slow the progression of the disease.

Hydration is one of the biggest pieces. Cats with CKD lose a lot of water through their urine, so they tend to run dehydrated. You can help by offering multiple water bowls around the house, trying a water fountain if your cat likes moving water, and feeding canned food or adding a little water to meals. In more advanced stages, your vet may teach you how to give subcutaneous fluids at home. It sounds intimidating at first, but many cats tolerate it surprisingly well, and it can make them feel much better.

Diet is another cornerstone. Special kidney diets are designed to be easier on the kidneys. They’re usually lower in phosphorus, moderate in high-quality protein, and balanced for things like potassium and sodium, often with added omega-3s. These diets have been shown to help cats feel better and may extend survival time compared with regular food. The catch, of course, is that cats are cats, and some of them aren’t thrilled with change. A slow transition, warming the food, or using a vet-approved topper can help. If your cat absolutely refuses prescription food, your vet can work with you to find the next best option. Keeping your cat eating is always more important than forcing the “perfect” food.

Depending on your cat’s lab work and symptoms, your vet may also suggest medications or supplements. These can include blood pressure medicine if hypertension is present, phosphorus binders when diet alone doesn’t keep phosphorus in range, potassium supplements if levels are low, medications for nausea and vomiting, appetite stimulants, and B-vitamins. In later stages, some cats need treatment for anemia caused by reduced erythropoietin production. Each cat’s plan looks a little different, which is why regular follow-ups and repeat lab work are so important.

So what can you do day-to-day, beyond the vet’s part of the plan? Think of yourself as your cat’s home nurse and advocate. Make water easy to reach, especially for older cats who don’t want to travel far. Keep litter boxes low-sided and easy to get into, and place them near favorite resting spots. Pay attention to patterns: how much your cat is eating, whether they are vomiting, how often you’re scooping the box, and how their energy level looks. A simple notebook or note app on your phone where you jot down fluids, meds, appetite, and behavior can be incredibly helpful for you and your vet.

It’s also important to know what “red flag” days look like. Call your vet or an emergency clinic right away if your cat refuses all food for more than a day, has repeated vomiting or severe diarrhea, suddenly seems extremely weak or wobbly, has trouble breathing, or shows sudden changes like seizures or bumping into things or going blind. These can be signs of a crisis that sometimes can be stabilized with hospital care and adjustments to their treatment.

On top of all the medical details, there’s the emotional side. Living with a cat who has kidney disease can feel like riding a wave. Some days your cat is bright-eyed, asking for breakfast and sunbathing in their favorite window. Other days they may seem tired or fussy about food and you wonder if things are getting worse. It’s completely normal to feel worried, sad, and even overwhelmed at times. Having honest conversations with your veterinarian about quality of life, comfort-focused care, and what the future might look like can actually be a relief. Toward the end, many families shift into a hospice mindset, focusing on keeping their cat warm, comfortable, well-loved, and free from pain. Those final months or weeks, handled gently, can be deeply meaningful time for both of you.

One last reminder before we wrap up this topic. This post is meant to give you a clearer picture of kidney disease in cats so you can spot early changes and feel more confident talking with your vet. It isn’t a substitute for an exam or professional medical advice. If you’re worried about your cat, or if your cat has already been diagnosed with kidney disease, your veterinarian is your best partner in figuring out the right plan for your particular kitty.