Kidney failure is very common in older domestic cats. In fact, it is one of the top causes of death in domestic cats. Read our complete guide on chronic kidney disease in cats to learn more about the disease, its symptoms and treatments, including a thoroughly researched dietary guide.

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What Is Chronic Kidney Disease

Kidney disease in cats is a severe and often incurable deterioration of the kidneys’ ability to filter out waste products from the blood. Usually, this deterioration happens over a longer period of time due to aging and general wear and tear. That is why we speak of chronic kidney disease (CKD) or chronic renal failure (CRF). Since the disease takes such a long time to develop, it is most commonly seen in older cats past the age of 7.

The Four Stages Of Chronic Kidney Disease In Cats

  • Stage 1: Around 40% of the kidney function is damaged. SDMA levels are raised, but blood urea nitrogen and creatinine levels are within range. This is the ideal time to start treatment, which underlines the need for early detection. If your cat is getting older, take her to the vet at least once a year for a full check-up.
  • Stage 2: At this stage, around 65% of the kidney function is lost. This means the kidneys are no longer able to maintain the required levels of vitamins and minerals in the blood. As a result, your cat will start to feel dehydrated and drink more and more water.
  • Stage 3: When the kidneys lose more than 75% of their function, your cat enters stage 3 of the disease. Toxins will start to build up in your cat’s bloodstream and outward symptoms will become more obvious.
  • Stage 4: In stage 4 your cat is in acute renal failure. She won’t be able to drink enough to keep up with her failing kidneys, nor can her kidneys keep up with filtering out the toxins. Needless to say, this is a time for immediate action.

If stage 4 kidney disease occurs without a history of chronic kidney disease, it is called acute kidney failure. As the name implies, acute kidney failure is a sudden onset disease, often caused by poisoning. It can occur at any age. If you suddenly see any of the symptoms described in this article in your cat, please take her to the vet or an animal emergency service immediately. If left untreated, acute kidney disease is either fatal or leads to chronic kidney disease.

Symptoms Of Chronic Kidney Disease In Cats

If caught early, there is a lot you can do to slow the progression of kidney disease and lengthen your cat’s life. Your vet can do blood and urine tests to see if your cat’s kidneys are damaged and, if so, how bad the damage is. In the meantime, we list the main symptoms of feline kidney disease to help you judge whether your cat has kidney problems and how far along it has progressed.

Excessive Thirst And Urination

The first obvious sign that your cat could be suffering from kidney disease is an increased thirst. And with that, increased urination. If you notice that your kitty starts to spend more time around her drinking bowl or suddenly leaves bigger puddles in the litter box, it is a good idea to take her for a check-up. Excessive urination can also be a symptom of diabetes, another disease that is best caught early.

Loss Of Appetite

A build-up of phosphorus in the blood leads to kidney-impaired cats being notoriously picky eaters. They tend to have trouble finishing their portions and will often snub their noses completely at the food you so carefully picked out for them. Don’t take it personally, and don’t force them to eat it. If you really can’t find anything she will consistently, and happily, eat, then consult with your vet about switching to a low phosphorus cat food for kidney disease.

Digestive Problems

In its advanced stages, kidney disease may co-occur with a host of gastrointestinal issues. The lack of minerals absorbed from food will cause disruptions in your cat’s digestive tract, which leads to vomiting and diarrhea. The inability to retain fluids further impairs the metabolic processes and increases the risk of constipation.

Cat sitting on a desk

Urinary Crystals

It is not uncommon for cats with kidney disease to develop urinary crystals or bladder stones. In fact, there is evidence suggesting that cats who suffer from urinary crystals at younger ages are more prone to developing chronic kidney disease later in life. If your cat has urinary crystals, she will show signs of pain while urinating. The urine may also contain traces of blood.

Kidney And Bladder Infections

The physical deterioration of the kidneys and decreased filtering of toxins can cause recurring infections to the bladder and the kidneys themselves. Your vet will perform regular analyses of your cat’s urine and subscribe antibiotics to treat the infections. You yourself can use nutritional supplements mixed in with your kitty’s food to limit the chance of infections occurring.

Lethargy And Depression

Cats tend to hide it when they are in discomfort or pain. So you can imagine how bad your kitty must be feeling when she actually starts to show it. It costs a lot of energy to keep going with damaged kidneys and as a result, your cat will become lethargic. On top of that, the chronic pain from her bladder and kidneys may even make her depressed. Not surprisingly, cats with kidney disease love to sleep the day away somewhere safe and comfortable.

Skin And Coat Problems

As the disease progresses, your cat will become more and more dehydrated. Toxins will start to build up in the bloodstream and get distributed throughout your cat’s system. This can lead to problems with her skin and coat, varying from dry skin and matte looking fur to rashes and hair loss.

Weight Loss

In the final stages of kidney disease, your cat won’t be able to absorb enough nutrients from her food to maintain her body mass. You will see a rapid loss of muscle and weight as your cat deteriorates. Consult with your vet about a change in diet and monitor her weight daily.

Treatments For Cats With Kidney Disease

Fluid Therapy

When your cat is first diagnosed with kidney disease, your vet will likely suggest that she undergo fluid therapy to flush out her renal system. A large quantity of fluids is administered to your cat either intravenously (into a vein) or subcutaneously (under the skin). For more serious or progressed cases, this process can be repeated several times over a period of days and at regular intervals throughout your cat’s future.

If your kidney diseased cat does require periodic fluid therapy and you want to save her the stress of the repeated vet visits, ask your vet about the possibility to administer the subcutaneous injections yourself at home. It may sound scary, but there really isn’t much to it once you know what you are doing.

Monitor Blood Pressure

Your cat’s blood pressure is an important gauge of her wellbeing and the progression of her kidney disease. As the toxins in her bloodstream go up and the nutrients go down, your cat’s heart will have to work harder and harder to keep up with the needs of her body. This will cause her blood pressure to rise. Monitoring the changes in your feline’s blood pressure over time can give a good indication of how well she is holding up.

Nutritional Supplements And Treats

Depending on the results of your cat’s blood work, you may want to consider adding specific nutritional supplements or a dietary treat to her food. Cats with kidney disease can often use some extra potassium, vitamin B and fatty acids (omega-3 and omega-6). If your cat suffers from loss of appetite, consider adding a phosphate binder to lower the levels of phosphorus in her blood.


Cats with kidney disease are unfortunately prone to developing kidney and bladder infections, as well as gastrointestinal complications such as a sensitive stomach or even hyperthyroidism. Your vet may prescribe some anti-inflammatory medication or antibiotics to help control these conditions. Of course, medication does put a strain on the renal system, so definitely use all of our other tips to prevent this from happening as much as possible.

Stress Management

Being ill in general is quite a load to bear for your poor feline. But stress and depression are especially detrimental to a cat with chronic kidney disease. A distressed cat may deprive herself of food or water just when she needs it the most, which can have devastating effects on her already compromised kidney function. An increased level of stress hormones also increases the risk of complications whenever your cat has to undergo more invasive treatments involving surgery and/or temporary hospitalization.

Find ways to reduce your cat’s stress levels, both in daily life and surrounding vet visits. In general, I would advise you to be extra attentive to your cat’s needs. A bit of spoiling and play goes a long way in building a cat’s self esteem. There are also a host of more controlled solutions available, ranging from calming sprays and powders to CBD-oil and hemp supplements. Consult with your vet and other pet owners about their experiences, so that you can make a well-informed decision about what is best for you and your cat.

Weight Management

When kidney disease gets really severe, your cat will start to lose weight quickly. To avoid you overlooking this suddenly appearing symptom, you should weigh your cat at least once a week. Write down her weight and the date, so that you have a clear log of her progression. In the meantime, manage her other symptoms and her calorie intake as best you can to help her maintain, or even gain, weight.

Proper Diet

Last, but most definitely not least, you should get your kidney disease cat on a healthy diet tailored to her exact needs. Now, as with all things related to feline nutrition, opinions on what exactly is a healthy kidney diet vary. Luckily, I don’t shy away from controversy. (Remember when I picked the hideous, plush cat tree over the sleek, modern one?)

The Protein Debate: Less Or More?

I have a stake in this debate as far as my cat having been diagnosed with kidney disease not too long ago. My vet advised me to put her on a low protein diet and offered me some sample packages of, surprisingly, dry food.

If there is anything I’ve learned about a cat’s nutritional requirements it’s that cats need high quantities of quality animal protein and moisture. Especially older cats, because of their increased metabolism. So it struck me as counter-intuitive when my vet suggested the exact opposite of that. I decided to do a bit of my own research to find out if my doubts were justified.

What I’ve found is that the views are indeed split when it comes to the benefits of less versus more protein in kidney diets. The main argument for low protein diets for kidney disease is that they relieve stress on the kidneys by reducing the amount of protein waste products in the blood. In the long term, this is supposed to slow down the progression of the disease. Sounds plausible, right?

Unfortunately, decreased waste filtering isn’t the only problem facing cats in renal failure. Limited kidney function also means that the good proteins themselves are less likely to be retained in the bloodstream. This is what leads cats with Stage 4 kidney disease to become physically weak and often just wither away.

Recent studies show that, despite the beneficial reduction in protein waste products in a low protein diet, the added building blocks available in a high quality protein diet have a significantly more positive impact on your cat’s overall health. A high protein diet helps to support your kitty’s weight throughout her life as a kidney patient, which gives her a better ability to fight off infections and make it through tougher times.

What is most important, though, is that your cat eats at all. Cats with kidney disease are difficult eaters, so sometimes it’s just a matter of finding something they tolerate, no matter the ingredients. Any food is better than none.

Whatever food you end up choosing for your cat, definitely consider adding some supplements to it. One thing that all cat experts agree on is the benefit of phosphate binders, potassium and fatty acids. If you just make sure your cat gets her supply of these, you are already helping to increase her quality of life.

A cat and a human giving each other a high five

Best Diet For Cats With Kidney Disease

After all my research, I definitely advise going for a diet that supports your cat’s health on as many fronts as possible. Therefore, I cannot in good conscience recommend feeding your cat an exclusively low protein diet. Because, let’s face it, what do you think those lost proteins get replaced with? Fairy dust?

A proper diet for cats consists of around 95% quality animal protein and (some) fat, and around 5% carbohydrates and fiber from vegetables. Most commercial cat food, and probably also yours, is instead loaded with cheap filler ingredients that have no place in a cat’s diet. Prescription veterinary diets are no exception, unfortunately.

Based on my findings, I have assembled the ideal requirements for a healthy diet for cats with kidney disease into an easy to follow list. Please use it as a guide to see if your cat food passes the test for felines in kidney failure, or if you need to supplement/replace it with something else:

  • High Quality Protein: Just like all sensible cat diets, high quality, easily digestible, animal protein should be the main ingredient of a diet for cats with kidney disease. Choose a protein source that is easy to digest and doesn’t contain too much fat. Poultry (chicken, turkey, duck) is an excellent option for kidney disease cats. Salmon is also a great choice, because it contains more omega-3 acids. However, fish can also contain more toxins, so try to balance it out.
  • Low In Carbohydrates: Most commercial cat foods, wet and dry, contain way more carbohydrates than are necessary healthy for your cat. Worst of all, these often come from cheap, difficult to digest sources such as wheat and corn. Eating too much of these filler ingredients can not only contribute to renal failure, but also set your cat on a path towards diabetes.
  • Low In Phosphorus: Increased phosphate levels are the most common and often earliest cause of appetite loss in cats with kidney disease. It stands to reason that a low phosphorus diet will help your cat to regain her appetite and maintain a healthy weight.
  • High In Potassium: Potassium plays a very important role in maintaining brain and muscle function. However, the increased drinking of a cat in renal failure can cause too much potassium to be removed from the bloodstream. Find a food that has added potassium, or choose a supplement that does.
  • Calcium: Cats with kidney disease often have high levels of calcium (hypercalcaemia), which is associated with a further progression of the disease. In those cases, low calcium foods are recommended. However, there are also cases where calcium levels are actually lowered through kidney disease (hypocalcaemia). Here the exact opposite applies.
  • Low In Sodium: Your kidney disease kitty’s food should be low sodium, as sodium increases the strain on the kidneys and raises your cat’s blood pressure.
  • Vitamin B: A disease that commonly occurs together with chronic kidney disease is hyperthyroidism, a gastrointestinal disorder that speeds up your cat’s metabolism. Vitamin B, in all forms, is great for digestive health and helps to combat some of the most debilitating aspects of both diseases.
  • Omega-3 And Omega-6 Fatty Acids: Fatty acids support the damaged kidneys in retaining healthy proteins in the bloodstream. The reduce the risk of inflammation and infection and, as such, can actually help in slowing down your cat’s kidney disease.
  • High In Moisture: Above all, a cat with kidney disease needs lots and lots of moisture. The more the better. Remember that cats aren’t the most avid drinkers and tend to only go for the drinking bowl if they need a little extra. So the fact that your cat in kidney failure is drinking excessively means she needs a lot extra. Help her out with a diet of exclusively wet food.

Read our guide on the Best Wet Food For Cats With Kidney Disease to get some specific product recommendations. Don’t feel discouraged if your cat won’t eat a certain type of food. All of the foods that we recommend are a step up from regular or dietary food. Whichever one your kitty settles for, you are already doing her a huge favor.

In case you absolutely can’t eliminate dry food from your cat’s diet, we also have a guide on the Best Dry Food For Cats With Kidney Disease. Just remember to supplement it with a high quality wet food and to always provide your feline with unlimited access to fresh water.

How Long Do Cats With Kidney Disease Live

I’m sure you’ve wondered about this if your cat has chronic kidney disease. I know I have. The truth is, it all depends on the progression of your cat’s renal failure and your proactiveness in treating it. The sooner it is diagnosed, generally, the longer you can stall the deterioration of her kidneys.

That said, even in later stages, progression of the disease is often characterized by longer periods where the symptoms seem to plateau and remain steady, followed by periods of sudden and more severe deterioration.

You can give your cat the best chance at a long and healthy life by taking her to the vet regularly. At least once a year. Preferably twice, if you have the resources. This way you can catch any diseases she may develop early and monitor her condition if she is diagnosed with one such as feline kidney disease.

Final Thoughts

Chronic kidney disease is incurable and often fatal, but with early detection and proper care your cat should be able to retain a good quality of life for a long time. A pure and natural diet with the right supplements can help to support her overall health and slow down progression of the disease from months to years.