Your Cat Has Kidney Disease. What Happens Now?

If your cat just got flagged for kidney disease at their last checkup, take a breath. This is scary news, and it’s okay to feel that way. Kidney disease, especially the chronic kind, is one of the most common conditions in older cats, and a diagnosis doesn’t mean the end. Caught early, many cats live comfortably for years with the right care and monitoring.

What kidney disease actually means for your cat

The kidneys do a lot of heavy lifting: filtering waste from the blood, balancing fluids and electrolytes, and producing hormones that help regulate blood pressure and red blood cell production. When the kidneys lose function over time, those jobs don’t get done as well, and waste products start building up in the bloodstream. That buildup is called azotemia, meaning elevated levels of nitrogen-based waste in the blood, and it’s what drives most of the symptoms you’ll notice.

Chronic kidney disease (CKD) is the slow, gradual version. It develops over months or years and is by far the most common form in cats, particularly those over age 10. Acute kidney injury (sudden-onset kidney failure) is different and typically caused by a toxin or infection. There’s also polycystic kidney disease in cats, an inherited condition where fluid-filled cysts grow inside the kidney tissue and slowly crowd out normal function. It’s especially common in Persian and related breeds.

Signs and symptoms of kidney disease in cats

The early signs of kidney disease in cats are subtle enough that most owners don’t notice them until a routine blood panel catches something. That’s not your fault. That’s just how CKD works.

Early warning signs to watch for:

• Drinking more water than usual
• Urinating more frequently or in larger amounts
• Gradual weight loss
• Eating less or showing less enthusiasm at mealtime
• A coat that looks dull or unkempt

As CKD progresses into later stages, the symptoms become harder to ignore:

• Vomiting, sometimes frequently
• Bad breath with a chemical or ammonia-like smell (from waste buildup)
• Significant muscle loss and weakness
• Lethargy and withdrawal from interaction
• Hiding or seeming mentally foggy
• Mouth sores or reluctance to eat due to nausea

Is kidney disease painful for cats? It can be, especially in later stages when nausea, mouth ulcers, and high blood pressure (which can cause sudden blindness) are involved. That’s one reason monitoring and early intervention matter so much.

How vets diagnose and stage CKD

Your vet will use a combination of blood tests and a urine test to figure out what’s going on and how far along it is.

The key markers they look at:

• Creatinine: a waste product filtered by healthy kidneys. High levels signal reduced kidney function.
• BUN (blood urea nitrogen): another waste product. Elevated BUN alongside high creatinine points toward kidney disease.
• SDMA (symmetric dimethylarginine): a newer, more sensitive marker that can detect kidney disease earlier than creatinine alone, sometimes with as little as 25% of kidney function lost, while creatinine typically stays within normal range until roughly 75% of function is gone
• Urine specific gravity: measured through a urinalysis, this tells your vet how well the kidneys are concentrating urine. Dilute urine is a red flag for CKD.

Once those results are in, vets use the IRIS staging system (International Renal Interest Society) to classify CKD into four stages based on creatinine and SDMA levels, with substages for blood pressure and protein in the urine. Stage 1 is the earliest and mildest; Stage 4 is end-stage kidney disease in cats, where kidney function is severely compromised.

Stage 2 kidney disease in cats is often where diagnosis happens, because SDMA and creatinine are clearly elevated but the cat may still seem normal at home. Stage 3 kidney disease means more significant function loss and more symptoms. Stage 4 is serious territory, with very poor filtration and a much shorter prognosis.

What treatment for kidney disease in cats looks like

There’s no cure for CKD, but there’s a lot you can do to slow it down and keep your cat comfortable. Treatment is about managing the disease, not reversing it.

Renal diet

A prescription renal diet is usually the first recommendation. These foods are lower in phosphorus and have controlled protein levels, which reduces the workload on damaged kidneys. High phosphorus accelerates kidney damage, so phosphorus binders (medications added to food to reduce how much phosphorus is absorbed from meals) are often prescribed alongside the diet in later stages.

Hydration and subcutaneous fluids

Keeping a CKD cat well hydrated is critical. Dehydration makes the kidneys work harder and accelerates decline. Many owners learn to give subcutaneous fluids at home, which means using a small needle to deliver fluid just under the skin (typically in the scruff of the neck), where it absorbs into the body slowly. It sounds intimidating, but most owners get the hang of it quickly, and it makes a real difference in how their cat feels.

Other medications your vet may recommend

• Blood pressure medications: hypertension is common with CKD and can cause serious complications, including sudden blindness.
• Anti-nausea medications: to help with appetite and comfort as waste products build up.
• Erythropoietin (or similar drugs): the kidneys produce a hormone that tells the body to make red blood cells. When kidneys fail, this drops off. Your vet may prescribe a synthetic version to address anemia, or low red blood cell count, which makes cats feel weak and fatigued.
• Potassium supplements: CKD cats often lose too much potassium through their dilute urine.

Your at-home CKD monitoring checklist

Between vet visits, you are your cat’s best early-warning system. Here’s what to track and when to act.

What to track	How often	What to watch for
Water intake	Daily	Measure how much goes into the bowl and how much is left. A sudden increase or decrease both matter.
Litter box output	Daily	Note how often your cat urinates and whether clumps are unusually large or small. Watch for straining or accidents outside the box.
Appetite	Daily	Did they finish their food? Show interest? Turn away entirely? Any consistent change is worth noting.
Vomiting	Daily	Occasional vomiting is one thing. Daily or multiple times a day is a call-the-vet situation.
Weight	Weekly	Use a kitchen scale and log it. Even a 2–4 oz drop over a week matters in a cat. Weight loss is one of the most reliable signs of CKD progression.
Energy and behavior	Weekly	Is your cat engaging with you? Grooming themselves? Jumping as usual? Subtle withdrawal or changes in activity are worth noting.

Red flags that mean call the vet today

• Sudden loss of appetite lasting more than 24 hours
• Vomiting more than once or twice in a day
• No urination in 12–24 hours, or straining to urinate
• Sudden disorientation, stumbling, or apparent loss of vision (a sign of dangerously high blood pressure)
• Rapid or labored breathing
• Complete collapse or unresponsiveness

Keeping a simple log, even just a notes app on your phone, gives your vet real data to work with at every follow-up appointment. It also helps you notice gradual changes that are easy to miss when you’re with your cat every day.

Does pet insurance cover kidney disease in cats?

Managing CKD is a long-term commitment, and the costs reflect that. Blood panels every few months, prescription renal food, subcutaneous fluid supplies, blood pressure medications, and specialist visits can add up to thousands of dollars over the course of your cat’s care.

A Lemonade accident and illness policy can help cover eligible costs related to CKD, including diagnostics, medications, and treatment, as long as the condition isn’t pre-existing. That means your cat shouldn’t be showing any signs or symptoms of kidney disease before your policy starts or during your waiting period. Because early-stage CKD often has no visible symptoms at all, many cats are flagged for the first time during a routine blood panel, which is exactly why getting coverage in place while your cat is healthy matters.

If your cat is healthy right now, this is the right time to get covered. You can’t predict when a routine checkup will turn into a diagnosis, but you can make sure you’re not navigating the financial side of it alone when it does.

Life expectancy and end-of-life decisions

Prognosis depends heavily on what stage the disease is caught. Cats diagnosed at IRIS Stage 1 or 2 with well-managed care can live for several more years with a good quality of life. Stage 3 is more variable. Stage 4 shifts the focus from slowing progression to keeping your cat as comfortable as possible.

If you’re approaching that point, you’re not alone in this. There’s no formula for when it’s time, but your vet can help you assess your cat’s quality of life honestly: whether they’re eating, resting comfortably, and having more good days than hard ones. When those good days become rare, that’s usually the clearest signal. Lean on your vet, ask the hard questions, and know that paying this much attention to your cat’s comfort is already an act of love.

Before we go

A kidney disease diagnosis is a lot to carry, and if you’re reading this because your cat was just diagnosed, know that learning everything you can is one of the most loving things you can do for them. CKD is manageable, especially when it’s caught early and monitored closely, and many cats go on to live comfortable, happy lives with the right care in place.

If your cat is still healthy, now is the time to think about coverage before you ever need it. And if you’re already in the thick of a diagnosis, we hope this guide gives you a clearer picture of what’s ahead. Either way, you don’t have to figure it out alone.

Frequently Asked Questions

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.