Chronic kidney disease in cats

With up to 40% of cats over the age of 10 and 80% of cats over 15 being affected, chronic kidney disease (CKD) is one of the most common and significant diseases in our feline friends.

While this condition is unfortunately progressive, studies indicate that prompt diagnosis and treatment can significantly slow the progression of disease and help affected cats to feel well for longer – purr-ific!

With that in mind, here is a timely dose of information on CKD in cats, including common symptoms, potential causes, and how to support your kitty friend’s best health and quality of life.

Understanding CKD in cats

Overall, the kidneys have three essential roles in the maintenance of health:

• Filtering the blood to create urine, which allows the body to:
  • Clear waste products from the body
  • Maintain appropriate hydration levels through conservation or elimination of water
  • Maintain blood chemistry (including electrolyte/salt levels and pH balance) within a healthy narrow range
• Helping to regulate blood pressure
• Producing a hormone that stimulates bone marrow to make more red blood cells (which carry oxygen)

CKD involves a progressive and irreversible loss of kidney function over a period of months to years. The progression of CKD in cats (and dogs) is officially grouped into four stages, known as the IRIS Staging System – but don’t worry, we’ll cover more on this below.

Common symptoms and warning signs

As the kidneys have a significant reserve capacity, cats in the earlier stages of CKD will often show no obvious outward signs, and will only develop symptoms of unwellness when they lose over 2/3 of their overall kidney function.

For this reason, some cases of early to moderate CKD are picked up on routine blood tests performed at a fortuitous time, while other cats may only be diagnosed when they present unwell with symptoms of more advanced kidney disease.

Early symptoms of CKD can be vague and unfortunately are easy to ascribe to “normal ageing” in a senior cat. They include:

• Gradual weight loss
• Reduced/variable appetite
• Reduced activity
• Increased thirst and urination

As the loss of kidney function progresses, affected cats may go on to develop additional symptoms including:

• Poor coat condition
• Vomiting
• Bad breath
• Thin body condition
• Symptoms of dehydration (such as reduced skin elasticity)

Up to 60% of cats with chronic kidney disease will also develop secondary hypertension (high blood pressure), which can cause changes to their eyes, brain and heart, and also worsen kidney damage – see our article on feline hypertension for more information on this.

Causes and risk factors

CKD is most commonly diagnosed in senior cats 10 years of age and above. In many affected cats, however, the exact cause of their CKD is unknown, because we often diagnose them in the later stages of a disease process that has been going on for months to years.

Some of the more common diseases/factors that we know can lead to CKD include:

• Polycystic kidney disease (PKD) – an inherited disease of the kidneys that is most frequently seen in Persian cats
• Bacterial kidney infections (pyelonephritis)
• Kidney tumours, such as lymphoma
• Mineralisations (“stones” or uroliths) that form in the kidneys or ureters (the tubes that connect each kidney to the bladder) and impede urine flow
• Certain drugs or toxins

Related: A guide to lumps and bumps on cats

Diagnosis of chronic kidney disease

Kidney function can be assessed with blood tests that check the levels of three waste products normally filtered by the kidneys into urine:

• blood urea nitrogen (BUN or urea)
• creatinine
• symmetric dimethyl arginine (SDMA).

The limitations of these tests are that they can be affected by other factors, such as the cat’s level of hydration and overall body condition. For this reason, it’s recommended that the cat also has concurrent urine tests performed to check their urine concentration, as elevated levels of the above blood parameters combined with inappropriately dilute urine (suggestive of excessive water loss) more strongly supports kidney insufficiency.

In addition, urine testing can screen for other parameters relevant to kidney health, such as the presence of bacteria or blood cells that could suggest urinary tract infection or inflammation, or elevated levels of protein that could suggest inappropriate protein loss through the kidneys (known as proteinuria).

In a cat who is being assessed for potential kidney disease, the veterinarian will also discuss further testing including blood pressure measurement (as CKD is a significant risk factor for secondary hypertension in cats), and sometimes, imaging such as kidney ultrasound or abdominal x-rays.

Once the relevant tests have been done, the cat’s stage of chronic kidney disease can be diagnosed according to the official IRIS staging system. This helps the vet to make the most appropriate recommendations for ongoing treatment, monitoring and management of the cat’s condition.

Related: Autoimmune diseases in pets: A vet-approved guide

Treatment and management for CKD

In cases where there is a current treatable underlying factor, such as a bacterial kidney infection, the vet will be able to prescribe specific therapy.

Unfortunately, however, CKD itself is a progressive, irreversible disease. Therefore, in most cases, the overall goals of management are:

• Supporting kidney function
• Treating any complications that arise from the kidneys not working as well
• Helping the cat to feel as well as possible
• Minimising any factors that can hasten kidney deterioration

Overall, this is done through:

• Minimising the build-up of waste products in the blood, which is most easily achieved through gradually transitioning the cat to a prescription kidney support diet (containing reduced levels of protein, phosphorous and salt)
• Maintaining good hydration through measures such as feeding a wet food formulation, setting up feline drinking fountains, and administering supplementary fluids if necessary (either subcutaneous or intravenous fluids, depending on the cat’s degree of unwellness)
• Regularly checking for and treating common complications of CKD (which can make the cat feel unwell and/or hasten kidney deterioration), including:
• Urinary tract infections
• High blood pressure
• Excessive urine protein loss
• Increased levels of phosphorous in the blood
• Decreased levels of potassium in the blood
• Anaemia
• Nausea or poor appetite
• In some cases, supplementing water-soluble vitamins (such as B-vitamins) that can become depleted in CKD cats

Related: What do cats eat? A guide to feline nutrition

Supporting your feline friend’s health

With chronic kidney disease being extremely common (particularly in senior kitizens), and often asymptomatic in the early stages, the best way to monitor your cat is through regular veterinary health assessments. It’s recommended to book your pet for a general health check:

• At least every 12 months for healthy cats up to 10 years of age,
• At least every 6 months for cats 10 years of age and older

If your cat has been diagnosed with CKD or another chronic health condition, they should ideally undergo a health check every 3-6 months.

As part of your pet’s assessment, as well as a physical examination, your veterinarian may recommend additional tests such as blood tests, urine tests, and blood pressure measurement.

Discover more articles and insights on The Dish.

23 Sep 2026