• Kidney disease is common in older cats
  One of the most prevalent health issues in cats, many cats suffer from failing kidneys, especially as they age.
• Causes vary, but often remain unknown
  Kidney disease can result from injury, genetics, or underlying conditions like infections or cancer. However, in many cases, the exact cause isn’t clear.
• Early detection and management are vital
  Spotting symptoms early, like increased thirst, vomiting, or lethargy can lead to better outcomes. Cats with renal disease can be made more comfortable with hydration, diet changes, and medications tailored to the cat’s condition.

Kidney disease in cats, especially chronic kidney disease (CKD), is one of the most common health issues in older felines, affecting up to 80% of cats over 15.¹ This problem worsens over time, affecting the body’s ability to remove waste, regulate hydration, and produce essential hormones.² Feline kidney disease often goes unnoticed in early stages, as cats may not show obvious symptoms. However, signs like increased thirst, frequent urination, poor appetite, and weight loss can indicate kidney problems in cats. As kidney disease progresses, they may develop complications such as hypertension (high blood pressure) and anemia (not enough red blood cells), which can cause lethargy, pale gums, and even vision changes. Early diagnosis is key. Vets use blood and urine tests to detect renal kidney disease in cats. It is important to note that with proper management, cats with kidney disease can still enjoy a good quality of life. As early detection and treatment can improve outcomes, regular check-ups are essential to catch kidney problems before they become severe.

Chronic kidney disease (CKD) is a progressive condition that commonly affects older cats, with a high prevalence in cats over 10 years of age.² As kidney disease worsens the condition moves through different stages.  Stage 1 kidney disease is very early disease.  When the condition enters stage 2 kidney disease in cats, signs may be subtle—like increased thirst, frequent urination, and mild weight loss. As the disease progresses to stage 3 kidney disease in cats or cat stage 3 kidney failure, symptoms become more noticeable, including vomiting, poor appetite, lethargy, and muscle wasting. In stage 4 kidney disease in cats, also referred to as feline kidney disease stage 4 or stage 4 renal failure, cats develop severe dehydration, anemia, high blood pressure, and an unkempt appearance. These are often considered cats with final stage kidney failure, and the clinical picture may include extreme weakness, pale gums, and disorientation. Understanding the signs and symptoms of kidney disease in cats helps clarify how kidney disease in older cats progresses. Whether it’s cat kidney insufficiency or end stage feline kidney disease, recognizing changes in behaviour and physical condition is key to understanding the impact of senior cat’s kidney problems.

While the exact cause of feline kidney disease isn’t always clear, research shows it’s likely due to a combination of factors. These include age, genetic predisposition, high blood pressure, protein loss in urine, and previous kidney injury. In many cases, kidney problems in cats develop slowly, with tiny damaging events adding to the destruction over time.³ By the time cats reach cat kidney failure stage 3 or cat kidney failure stage 4, the kidneys have suffered irreversible damage. This progression leads to end stage feline kidney disease. Understanding what causes kidney disease helps explain why older cats with kidney disease require careful monitoring and early intervention to slow the disease’s advance.

In cats with chronic kidney disease (CKD), the kidneys gradually lose their ability to filter and remove waste products from the body. As this function declines, waste (especially from the use of dietary protein in the body) can build up in the bloodstream, making cats feel unwell. One of the most effective ways to support cats with kidney failure final stage is through fluid therapy which helps dilute the wastes, correct dehydration, improve blood flow to the kidneys, and flush out toxins. In hospital settings, intravenous fluids are used to stabilize cats, while long-term hydration can be maintained at home with subcutaneous fluids or even water via feeding tubes.

Diet also plays a critical role. A kidney diet for cats is specially formulated to reduce protein and phosphorus levels, which lowers the amount of waste the kidneys need to process. This helps reduce the workload on the kidneys and may slow disease progression. Because the kidneys are involved in many vital functions, like balancing electrolytes, regulating blood pressure, and producing hormones, ongoing monitoring and medications may be needed to maintain hydration, body weight, appetite, blood pressure, and blood and urine values.

Kidney disease in cats doesn’t usually happen overnight, it’s a slow, complex process that can take years to develop. According to Dr. Jepson, the most common form, feline chronic kidney disease, is linked to long-term inflammation and scarring in the kidneys, known as tubulointerstitial nephritis.³

While the exact cause isn’t always clear, studies show that kidney failure in cats is influenced by a mix of genetics, environment, and individual health history.³ These factors can lead to progressive damage, especially in older cats with kidney disease. 
Risk factors that may predispose cats to CKD include:

• Poor body condition or weight loss
• Dental disease
• Cystitis (bladder inflammation)
• Male neutered cats (vs. female spayed)
• Dehydration or anesthesia in the past year
• Exposure to kidney toxins or nephrotoxic drugs
• Systemic hypertension (high blood pressure)
• Hyperthyroidism
• Possible breed predisposition (e.g., Persian, Abyssinian, Siamese, Ragdoll, Maine Coon)

Preventing CKD means managing these risks early; keeping your cat hydrated, maintaining dental health, and avoiding unnecessary exposure to toxins or stressors.

^{1. Marino CL, Lascelles BD, Vaden SL, Gruen ME, Marks SL. (2014) Prevalence and classification of chronic kidney disease in cats randomly selected from four age groups and in cats recruited for degenerative joint disease studies. J Feline Med Surg.16, 465-472. doi:10.1177/1098612X13511446}

^{2. Sparkes AH, Caney S, Chalhoub S, et al. (2016) ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease. J Feline Med Surg. 18, 219-239. doi:10.1177/1098612X16631234}

^{3. Jepson RE. (2016) Current Understanding of the Pathogenesis of Progressive Chronic Kidney Disease in Cats. Vet Clin North Am Small Anim Pract. 46, 1015-1048. doi:10.1016/j.cvsm.2016.06.002}

^{4. Taylor AR, McDonald J, Foreman-Worsley R, Hibbert A, Blackwell EJ. (2025) Mortality and life table analysis in a young cohort of pet cats in the UK. J Feline Med Surg. 27(4):1098612X251314689. doi:10.1177/1098612X251314689}

^{5. Gray C, Radford A. (2022) Using electronic health records to explore negotiations around euthanasia decision making for dogs and cats in the UK. Vet Rec. 90:e1379. doi:10.1002/vetr.1379}