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Chronic Kidney Disease in Cats: Causes, Symptoms & Cure

Chronic kidney disease is a serious health condition that affects cats. It’s reasonably common, but you may not know a lot about it. So, what causes CKD in cats, what are its symptoms, and can you cure it?

What is chronic kidney disease/CKD in cats? CKD is where the kidneys suffer physical damage from one of many sources, which means they can’t do their job properly. This damage means they can’t clean the blood properly, filter it of toxins, or properly maintain the levels of water and mineral salts in the body. There is no cure for CKD although the condition can be managed (stopped from getting worse). Left unchecked CKD will kill your cat eventually. It is most common in older cats but can happen, albeit rarely, in other periods of life. Causes include kidney stones, infection of the urinary system, kidney lymphoma, genetic problems (e.g. in Persians), not getting enough water, and ingesting toxins. Symptoms include weight loss, hair loss, bad breath, lethargy and depression, increased drinking, vomiting, diarrhea and anemia.

The guide below first looks at what CKD is and whether/why it can kill a cat. It will then look at each of the causes and symptoms of CKD in turn, exploring each deeply so that you understand what’s happening to your cat and why. It will also look at how to manage the condition and prolong your cat’s lifespan as much as possible.

What Is Chronic Kidney Disease?

Chronic kidney disease can affect cats young and old. It has many causes and many symptoms, so can be hard to diagnose.

Chronic kidney disease is a condition that affects a cat’s kidneys, particularly in old age. The equivalent condition in people is called kidney failure. This is where the kidneys sustain physical damage for one reason or another, so lose some or all of their function.

Cats have kidneys just like we do. Healthy cats have two, although it is possible for a birth defect to give a cat more than one (although this doesn’t impair their function). It’s also possible for a cat to survive with only one kidney, as it is for people. The kidneys are located on either side of the spine towards the tail-end of the cat, deep in the abdomen. The kidneys are essential organs that the cat needs for several reasons, so kidney failure is a serious condition.

Estimates for how common CKD is in cats vary. It’s thought that somewhere around 1-3% of cats develop CKD at some point in their lives. It’s far more common in a cat’s old age than it is earlier in life, but it can occur at any time.

Can Chronic Kidney Disease Kill a Cat?

Because the kidneys are vital organs, this has dramatic knock-on effects and can kill your cat. The kidneys perform vital roles, such as:

  • Taking waste water from the bloodstream to produce urine.
  • Maintaining homeostasis with regard to water, sodium and potassium. Homeostasis is a fancy word for balance used by biologists. The mammalian body has to maintain an accurate and constant balance of water and ‘salts’ (certain chemicals) in the body to ensure good health. The kidneys filter out more or less water/salts to keep their levels balanced, e.g. filtering out less water in hot conditions or more water when the cat drinks a lot.
  • Filtering toxins from the bloodstream. If your cat accidentally ingests something it shouldn’t, like a poison, its kidneys are its first line of defence. They filter the toxin from the blood and excrete it with urine.
  • Producing certain hormones. These hormones aren’t as well known as others, but they perform important functions like stimulating red blood cell formation.

If the kidneys aren’t doing their jobs properly, issues related to these functions become obvious.

What Causes Chronic Kidney Disease in Cats?

Chronic kidney disease doesn’t have a singular cause. You could compare it to something like breaking a bone: it’s a well-defined problem, but could have been caused in one of many ways. Below is a list of potential causes, one or more of which may be relevant to your cat’s ill health.

CKD Can Be ‘Idiopathic’

If you talk to a vet, they’re most likely to say that the condition is ‘idiopathic’. Idiopathic is a term that refers to health conditions which arise spontaneously without an obvious cause. In simple terms, the vet may be unable to identify the reason why your cat developed CKD.

To receive a diagnosis of idiopathic CKD is frustrating because you may think you don’t know what you did wrong. However, conditions like these can be entirely out of the owner’s control. And besides that, it doesn’t make much difference whether your cat’s CKD was caused by one thing or another; its effects are the same, and the recommendations your vet will make will be the same too.

Not Getting Enough Water

Water is essential to the functioning of the kidneys. It’s the kidneys’ job to filter water from the bloodstream; you could think of it as the oil that runs through a machine. If the kidneys don’t get enough water, then they might not work properly in the same way as a machine that’s not kept oiled.

The best example of this is the formation of kidney stones. Kidney stones are made of minerals that are naturally found in urine. Normal kidney function flushes these unwanted minerals from the tiny nooks and crannies of the kidney and excretes them in urine. But when there’s hardly any water to flush them out, they can conglomerate and form something bigger and bigger. Eventually, a kidney stone can get so big that it can’t even fit in the tube that exits the kidney. It can get stuck and kill your cat, or it can scrape against the walls of the kidney and cause infections—all because your cat didn’t get enough water.

It’s surprisingly easy for a domestic cat to not get as much water as it needs. There are two reasons for this. One is that you may feed your cat dry cat food (kibble). While kibble contains most of the nutrients cats need, it doesn’t contain much water, and cats get most of their water from their food. This ties into the second reason why cats struggle to get water, which is that they naturally hardly drink at all. They prefer to get their water from food, like meat, which is surprisingly high in water (at about 60% on average).

Some of the causes below relate directly to not getting enough water. Kidney infections, for example, are more common in cats that don’t drink much or which eat dry food.

Old Age

Old age is in some senses a cause of CKD, too. CKD is most common in cats which are in their later years, for two reasons.

  1. Kidney damage from not getting enough water takes a long time to appear. It adds up over a long time, meaning that it only gets to the level of kidney failure in the cat’s old age.
  2. Organs gradually lose function as an animal ages. That’s both because of damage adding up, and because the body naturally loses condition—that’s why we get wrinkles, why a cat’s fur gets dull, and the many other impacts of ageing occur.

There is famously no cure for old age, so your cat may develop mild or even severe moderate CKD solely as a result of the ageing process.

Polycystic Kidney Disease (PKD)

PKD is a kidney condition that typically affects Persians and similar breeds. What happens is that the kidneys are gradually damaged by small fluid-filled cysts. Like other kinds of damage, this problem gets worse over the years until kidney function is impaired and CKD can result. Around one third of Persian cats are affected.

PKD is a genetic issue. It is inherited by an affected cat’s offspring. As such, cysts are present from birth. As the cat ages, though, the cysts become larger and larger. According to VCA Hospitals, the issue is the result of a single genetic change.

Because the cysts that cause PKD are present from birth, in rare cases, they can cause CKD from a very early age—even in kittens. There is no way of knowing how many cysts the cat has in its kidneys or how quickly they will grow, making this a highly variable condition. These cysts cannot be removed or made smaller.

Kidney Tumors

Cats can develop tumors in their kidneys. These can have the knock-on effect of reducing kidney function and causing CKD. According to

Renal lymphoma appears to be a disease of the older cat. Cases usually present with reduced appetite and weight loss. Often an owner identifies a large intra-abdominal mass that is actually the enlarged left kidney. These cases invariably present with a degree of renal failure. Diagnosis is best made on a fine needle aspirate of an enlarged kidney. While they can be responsive to chemotherapy, the significant kidney damage that has inevitably arisen prior to diagnosis persists. This has consequences both in the short and the long term. In the short term, chemotherapy drug metabolism will inevitably be affected by the reduction in renal function. In the long term, renal damage is likely to be progressive and therefore, even if the lymphoma enters complete remission, life expectancy can be reduced.

In other words, kidney tumors have two effects. One is that they reduce kidney function in the here-and-now. The other effect is that they reduce kidney function long-term by causing damage to the kidney, even if they’re gotten rid of with chemotherapy. Kidney lymphomas early in life can therefore cause CKD later in life.

Kidney Infections in Cats

A kidney infection is where bacteria get into the kidney and multiply. This happens when a cut or scrape occurs in the kidney as a result of a kidney stone. The bacteria can then get inside the cut. Your cat’s body then has to fight off the infection as it would anywhere else in the body.

When the body notices an infection, it swells the area up. This allows more white blood cells to get to the area, so that they can kill the bacteria cells (because white blood cells travel in the blood). The more white blood cells in an area, the quicker they can get an infection under control. Unfortunately, the swelling, the bacteria and the scar tissue from the wound can all combine to cause permanent damage in the same way they can on the skin. If your cat experiences many kidney infections over its life, it can end up with lots of scar tissue, meaning that its kidneys dont work as well as they would otherwise. Enough damage can add up to cause kidney failure.

Ingestion of Toxins

cat throwing up
Ingested toxins can damage the kidney irreparably.

The kidneys’ job is to filter the blood. Not only do they remove excess water from the bloodstream, but they remove any toxins that they find in the blood. ‘Toxins’ doesn’t mean something vague here, but actual toxins: poisons that are ingested, such as cyanide or rat poison. The kidneys are therefore the first line of defence against poisons that have entered the body. While the kidneys are excellent at filtering out these toxins, that doesn’t mean they’re immune to their effects. Toxins can damage the kidneys in the near-term, but can also cause permanent damage.

If you think your cat has ingested poisons, take it to the vet as soon as possible. Collect samples of any diarrhea or vomit your cat produces. Watch out for symptoms like breathing problems, shivering and tremors, vomiting and diarrhea, coughing and drooling, confusion and weakness.


This is a condition where the glomeruli—the small individual units that make up the kidney, each of which filters the blood—becomes swollen. Glomerulonephritis is actually a group of diseases all of which have this same effect. It can be caused by problems with the immune system, the effect of other conditions, or have no clear cause.

The swelling itself causes immediate loss of kidney function. This swelling can be prolonged if the underlying cause is not addressed, and long-term swelling can cause permanent damage, providing a further cause of CKD.

Other Causes of CKD in Cats

Those above are the most common, but they are certainly not the only causes of CKD. Other causes of kidney failure in cats include:

  • Genetic malformation of the kidney that isn’t polycystic kidney disease.
  • Amyloidosis. This is when there’s a build-up of a particular protein in the kidney that stops it from functioning as it should.
  • Viral infections of the kidney. Feline leukemia virus (FeLV) and feline infectious peritonitis virus (FIP) can both affect the kidneys and stop them working properly.

As well as each of these individual problems, your cat’s CKD could be a combination of some, even all of them. Your Persian cat may have cysts on its kidneys, have experienced kidney infection and kidney stones earlier in life, and may have had a bad run-in with a poison several years ago. These causes can all combine so that later in life it experiences severe CKD.

What Are The Signs & Symptoms of Chronic Kidney Disease in Cats?

Because the kidneys are such vital organs, there are many symptoms associated with their failure. However, which symptoms you will see depend on how severe the condition is. That’s why vets say there are severale stages of CKD. There is no agreed-upon way of classifying CKD, but what every vet agrees upon is that there are clear differences between the least severe and most severe examples, and that the issue can progress from those early stages to the later stages in a defined way. Here is the table issued by IRIS, the International Renal Interest Society, with the most universally accepted measurements:

Stage & DescriptionSerum Creatinine Concentration mg/dLSerum Creatinine Concentration mcmol/L
Stage 1, Nonazotemic CKD< 1.6<140
Stage 2, Mild Renal Azotemia1.6 to 2.8140 to 250
Stage 3, Moderate Renal Azotemia2.9 to 5251 to 440
Stage 4, Severe Renal Azotemia> 5> 440
Note: Azotemia means ‘kidney damage’.

This is a measurement of how much creatinine can be found in blood serum. The higher the level of creatinine, the worse a job the kidneys are doing. While the cause of the symptoms below isn’t high levels of creatinine, it is a useful way of assessing how bad a cat’s kidney damage is. Let’s take a look at the symptoms associated with the early stages and the late stages.

Early Stage CKD Symptoms

CKD can lower coat quality.

During the early stages of CKD, it is likely that you won’t notice any symptoms at all. The damage to the kidneys is, of course, internal, and it takes time for slight kidney damage to have knock-on effects on the rest of your cat’s health. Besides that, the early symptoms of CKD can easily be dismissed as typical signs of ageing. This leads many owners to allow the condition to get worse without seeking treatment.

One key early symptom is that your cat will drink more than normal and pee more than normal. This behavior is triggered because the kidneys are unable to filter things out of the blood effectively. What drinking more does is effectively dilute the concentration of these bad things in the blood stream, so that they dont have as bad an effect. This, of course, is an unconscious behavior. Something you won’t notice, but your vet will, is that this causes an increase in blood pressure because there’s more volume to the blood as a result of increased water content.

Your cat may also lose weight. In the beginning, this isn’t obvious, but it can progress until your cat loses lots of weight. The reason for this is that your cat loses its appetite, and since it isn’t eating, it uses its fat reserves—like when you go on a calorie-restricted diet. You may also notice that your cat’s coat becomes less lustrous, that it’s thinner, or that it’s more matted. This is a combination of your cat being unhealthy and not grooming itself as much. Weight loss and poor coat quality are two symptoms that can easily be mistaken for the signs of ageing.

Two other early signs are mouth ulcers and bad breath. Your cat may develop ulcers because its kidneys can’t filter acidic urea from its bloodstream (although the exact reason why ulcers form isn’t clear). Bad breath (often with a urine smell) is a result of the same cause.

Late Stage CKD Symptoms

As CKD progresses, each of the symptoms above becomes more serious. Your cat will drink even more and pee even more, its blood pressure will go higher, it will lose more and more weight, and its coat will will continue to lose quality. However, these are not the only symptoms you can expect to see. Symptoms of late stage CKD include:

  • Nausea and vomiting. These are generic signs of poor health.
  • Lethargy/depression. Lethargy is where an animal stops moving around as much. It may be so inactive that it doesn’t even get up to eat or go to the toilet.
  • Death. All cats with severe CKD will eventually pass away as a result of the condition or its complications. In severe cases, the question is how long life can be extended or how comfortable the cat can be made before it passes.

In the latest stages of CKD, life expectancy can be as short as days or weeks. In the early stages, if the condition is diagnosed and managed, the cat can live a happy and healthy life almost as long as a healthy cat. It’s therefore imperative that you talk to a vet as soon as you suspect your cat’s ill health.

How to Prevent Chronic Kidney Disease in Cats

It may be an old saying, but that means it’s no less true: prevention is better than cure. You should try to stop CKD before it starts, because the damage it causes is irreversible. Fortunately, there are things you can do right now that will dramatically reduce the risk of CKD occuring.

Switch From Dry Cat Food to Wet Cat Food

Your cat prefers getting its water from food rather than drinking it. That’s because the meat your cat would eat in the wild contains lots of water; meat is 60% water on average. As such, if you feed your cat dried food, this can cause or exacerbate poor kidney health.

You should therefore consider switching your cat from dry food to wet food. It can be difficult to switch your cat from one kind of food to another. Cats can be picky. You could try buying a couple of different flavors of food, or a few different brands, to see which your cat prefers. There are lots of different wet foods available: raw and cooked, fish or meat, with gravy or without, organic and non-organic, expensive and not expensive. There should be something your cat likes in the wide range available.

Mix Water Into Your Cat’s Dry Food

If wet cat food isn’t available to you, or if your cat refuses to switch to it, you still have options available. What many owners do is pour a little water into their cat’s kibble and mix it around. If you press it down, it can become roughly the consistency of wet cat food.

This is even a good idea if your cat shows no signs of CKD. Not only does it add more water to your cat’s diet, which is a good thing, but it can encourage a picky cat to eat. Adding water to dry kibble and mixing it around releases its aroma, which the cat may find more tempting than dry food alone. The one drawback is that if you leave the food to sit for hours, it can go bad in the same way that wet cat food can go bad.

Buy a Cat Fountain Water Bowl

Another way of getting more water into your cat’s system is by changing the way it drinks. You can do this by buying a cat fountain water bowl. These are exactly what they sound like: bowls that have some kind of waterfall or fountain built in so that the water runs rather than sits still.

The point isn’t that they’re fancier or more expensive than normal water bowls. The point is that they’re more appealing to cats, so your cat will want to drink more. The reason for this stems back to your cat’s history as a wild cat. In the wild, when you’re picking a water source to drink from, it’s better to pick a running source rather than a still source. That’s because still water can develop all sorts of nasty algae and bacteria which will make an animal sick. Running water like a stream can still make an animal sick, but it’s much less likely to do so, because algae and bacteria don’t have time to reproduce before the stream runs on. Picture yourself if you were lost in nature somewhere: would you rather drink from a still green pool of water or a clear stream?

In practise, this means your cat would prefer drinking from a running source than a still one. So, if your cat doesn’t like drinking from its bowl, it may drink more if you buy a cat water fountain.

How to Fix Chronic Kidney Disease in Cats

Given how serious chronic kidney disease is, your first thought will be how to fix it, or at least how to stop it getting worse. That’s what this section of the guide is about.

CKD Is Not Curable

The name ‘chronic kidney disease’ may suggest that this condition can be reversed and cured. However, CKD is simply another name for kidney failure. Kidney failure is where the kidneys are irreversibly physically damaged by one cause or another, like tumors or cysts as described above. While a mammal’s body can repair itself to some extent, this is one thing it can’t do. There also isn’t any kind of medicine that can physically repair your cat’s kidneys.

While this may seem pessimistic, there are still things you can do. It is possible to make your cat much more comfortable, prevent the issue from becoming worse than it already is, and extend your cat’s life considerably.

Talk To a Vet

Whenever your cat is ill, whatever the reason, you should take it to the vet. This is important even if you believe you know what the condition is, think it is an incurable condition like CKD, or if it’s inconvenient to do so. That’s because:

  • You may be incorrect in your diagnosis. You may think that the condition is an untreatable one, when it is easily treated; or, you may think it is a trivial issue when it’s one that could kill your cat. The vet can tell you whether your suspicions are right or not using their years of experience and medical knowledge.
  • The vet has access to medications that you can’t get anywhere else. While there are no medicinal cures for CKD, your cat could benefit from pain medication. Or, if the condition is something other than CKD, you can get medication for that condition instead. CKD may also appear alongside kidney or urinary tract infections in which case antibiotics may help.
  • The vet can accurately monitor the progress of your cat’s condition to see if it gets worse.

Vet checkups for cats are cheap and there may be finance available to you if necessary. Remember that you can always ‘shop around’ if you need to find a vet that suits your budget. The potential alternative is that your cat suffers more than it needs to.

The vet may follow IRIS guidelines on how to treat CKD depending on the stage of the condition. The guidelines are as follows:

IRIS StagesDiagnostic/Treatment FocusConsiderations
Stages 1 & 2, Early Stage 3Assess primary disease and complicating disorders (check how bad the problem is, see what’s causing it, and what knock-on effects it has)Specific diagnostics/therapies:
1) Ultrasonography/urine culture to rule out ascending UTI; antibiotics for pyelonephritis
2) Radiography and ultrasonography (with or without FNA) to rule out renal infiltrative disease and obstructive uropathy; chemotherapy (renal LSA) or subcutaneous ureteral bypass (ureteral obstruction)
3) Assessment of serum calcium/ionized calcium to rule out hypercalcemic nephropathy
Stages 2 & 3, Early Stage 4Assess CKD stability/progression (ensure that the condition stablizes and doesn’t get any worse than it already is)Renoprotective therapy to slow CKD progression:
1) Hyperphosphatemia: Renal diets with or without intestinal phosphorous binders to control serum phosphorus (Stage 2, < 4.5; Stage 3, < 5; Stage 4, < 6)
2) Hypertension: Calcium-channel blockers and/or ACE inhibitors
3) Proteinuria: ACE inhibitors and/or calcium-channel blockers
Late Stage 3 & 4Assess patient problems (ensure that your cat is as comfortable as possible)Symptomatic problems and treatments:
1) Metabolic acidosis: Dietary alkalization
2) Potassium depletion: Potassium supplementation
3) Dehydration: Oral rehydration/parenteral fluid therapy
4) Anemia: Recombinant erythropoietin
5) Calorie malnutrition: Appetite stimulants, dietary variety, feeding tube placement

They may also choose to follow the guidelines of other similar organizations. The treatment focus is broadly the same, however: assessing the damage and making the cat as comfortable as possible.

Follow Your Vet’s Recommendations

The vet may be able to tell you the reason or reasons why your cat developed CKD. These triggers may be within your control, such as dry food. You should therefore follow all of the prevention guidelines above even if your cat already has CKD. This will slow down or even halt the progress of the disease. This could mean that your cat’s lifespan is extended until it’s almost that of a healthy cat.

Your vet will also recommend several adjustments to your cat’s diet and lifestyle because of its condition. One is that your cat eats food with lower protein content than normal. That’s because many of the toxins in your cat’s bloodstream are the result of protein breakdown. So, while cats need lots of protein in their diets, in this particular instance they should have less. Your vet may recommend a particular low-protein food that you should give to your cat; follow their recommendation, because it’s easy to give your cat too little protein, which is bad too.

They may also recommend that you feed your cat a diet that has a low phosphate content. It’s thought that while a low protein diet can improve the quality of life in a cat with CKD, a low phosphate diet can slow the progress of the disease and ensure that your cat lives longer.

Other measures include:

  • A diet that’s high in antioxidants. Antioxidants can prevent damage to the kidneys (although not repair it and reverse your cat’s CKD).
  • A diet that’s high in essential fatty acids. This helps maintian blood flow through the kidneys and reduces inflammation.
  • Adding potassium to the diet. This prevents hypokalemia, which is low blood potassium level.
  • Adding bicarbonate to the diet. This prevents acidosis, i.e. the build-up of acid throughout the body. This occurs because the kidneys fail to filter acidic urea from the blood.

Make Your Cat Comfortable

However bad your cat’s CKD, you should try to make it more comfortable. This is especially the case if your cat is in its old age. This will make its life easier, in the same way that a person with a recurring medical condition should take lots of bed rest and not overexert themselves. Ways you can make your cat with CKD more comfortable include:

  • Keeping everything your cat needs on one floor of your home. This will stop your cat from climbing the stairs.
  • Not providing your cat with toys that will make it too active. Certain toys encourage very high levels of activity, such as laser pointers. You should allow your cat to play, but not in a way that will have it playing too long or too much.
  • Not letting your cat out as often, or force it to go out. When it’s outside your cat will be more active: it will climb, jump, run and generally get into trouble. There are fewer ways for it to overexert itself inside.
  • Buying a heated cat bed. These are like normal cat beds but have some way of keeping your cat nice and warm. Some plug into outlets, while others have space-age heat-reflective materials built in. Either way, they’re good for helping a cat recover from or manage a health condition.
  • Giving your cat lots of affection (if it wants you to). Affection is good for the soul. You should do everything you can to keep your cat happy, including lots of affection.

It’s good to make your cat comfortable whether it’s ill or not, so consider following these guidelines even if your cat doesn’t have CKD!