Introduction
Kidney disease is one of the most common health issues seen in cats, especially as they age. According to studies, the prevalence of kidney disease in cats is estimated to be around 1-3%, with higher rates seen in older cats. However, some estimates put the prevalence as high as 7.6% in the overall feline population.[1][2] Kidney disease can have a significant impact on quality of life and lifespan in affected cats.
This condition develops gradually over time and cats can compensate for declining kidney function for a while before showing outward signs. By the time symptoms appear, the disease is usually quite advanced. For this reason, regular screening blood and urine tests are important to detect kidney disease in earlier stages when treatment may slow progression of the disease.
Risk Factors
Certain factors can increase a cat’s risk of developing kidney disease. Age is one of the biggest risk factors. Older cats, especially those over 10 years old, are more prone to kidney problems (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4864943/). Certain breeds like Persian cats and Abyssinian cats are genetically predisposed to kidney issues. Obesity is another major risk factor, as the excess weight puts strain on the kidneys. Overweight cats have a 1.6 times higher risk of kidney disease. Hypertension, or high blood pressure, also damages the kidneys over time. Cats with hypertension have a 3.5 times greater chance of developing kidney failure (https://www.pethealthnetwork.com/cat-health/cat-checkups-preventive-care/6-surprising-facts-about-kidney-disease-cats).
Diet
Poor quality diet can contribute to the progression of kidney disease in cats. Diets high in phosphorus, protein and salt can put additional strain on the kidneys by increasing workload. According to the IVJ Journal article “Nutritional management of chronic kidney disease in felines”, diets should be “Energy dense and low in sodium, phosphorus, and protein.”1
Phosphorus is abundant in muscle meats, dairy products, fish, and organ meats. Excessive phosphorus binds to calcium, leading to mineral imbalances and can cause secondary renal hyperparathyroidism.2 Reducing phosphorus intake through diet modification is important to prevent disease progression. Homemade diets should be formulated under veterinary supervision to ensure proper nutrient balance.
Dehydration is also problematic in cats with kidney issues. Increased water intake helps dilute toxins and ease workload on the kidneys. Adding more moisture to food through wet formulations or by adding water can encourage increased fluid intake.
Toxins
Certain toxins can worsen kidney disease in cats by damaging the kidneys directly. Some of the most notable toxins that owners should be aware of include antifreeze, lilies, and NSAIDs.
Antifreeze contains ethylene glycol, which is highly toxic to cats [1]. Even small amounts can lead to kidney failure and death if untreated. Owners should keep antifreeze securely out of reach and clean up any spills immediately.
Many types of lilies are also extremely toxic to cats’ kidneys, including Easter lily, tiger lily, rubrum lily, Japanese show lily, and some daylilies [2]. Even small ingestions can cause irreversible kidney damage. Lilies should not be kept in homes with cats.
Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can also be dangerous for cats, especially at high doses. NSAIDs can reduce blood flow to the kidneys, worsening any existing kidney issues [3]. Owners should only give NSAIDs under veterinary supervision and direction.
Infections
Infections, especially urinary tract infections (UTIs), can worsen kidney disease in cats. One serious renal infection is pyelonephritis, inflammation of the kidney and renal pelvis. Pyelonephritis is often the result of bacteria traveling up the urinary tract from the bladder to the kidneys. Some common causes include bladder or dental infections spreading to the kidneys (1).
Dental disease is a major predisposing factor for pyelonephritis in cats. Bacteria from the mouth and damaged teeth can enter the bloodstream and infect other areas like the kidneys. One study found that cats with kidney infections were 6 times more likely to have dental disease than cats without kidney infections (2). Treating dental infections and maintaining good oral health is important for preventing pyelonephritis in cats prone to kidney issues.
Other common UTIs in cats that can progress to pyelonephritis include bacterial cystitis and urethritis. Catching and treating lower UTIs quickly is key to preventing the spread of bacteria to the kidneys. There are also some bacteria more likely to cause pyelonephritis in cats, like E. coli and Staphylococcus (1). Knowing the type of infection can help guide treatment.
(1) https://www.merckvetmanual.com/cat-owners/kidney-and-urinary-tract-disorders-of-cats/infectious-diseases-of-the-urinary-system-of-cats
(2) https://www.petmd.com/cat/conditions/urinary/kidney-infections-cats
Other Diseases
Certain diseases that affect cats can worsen kidney disease. Some of the main diseases that negatively impact kidney health in cats include:
Hyperthyroidism
Hyperthyroidism is an endocrine disorder characterized by overproduction of thyroid hormone. According to VCA Animal Hospitals, hyperthyroidism is present in about 20-30% of cats with chronic kidney disease. The excess thyroid hormones can accelerate kidney damage by increasing blood flow through the kidneys.
Diabetes
Diabetes mellitus is a disorder of carbohydrate metabolism caused by inadequate insulin production or utilization. According to Pet Health Network, the excess blood glucose levels in uncontrolled diabetes can damage the delicate filtering structures in the kidneys over time.
Cancer
Cancerous growths anywhere in the body can potentially spread to the kidneys. According to PetMD, lymphosarcoma, which is a form of lymphoma, is one of the more common cancers that can directly affect the kidneys. The abnormal cancer cells disrupt normal kidney function.
Diagnosis
There are a few different tests vets use to diagnose kidney disease in cats:
Blood and urine tests can detect elevated levels of urea and creatinine, which are waste products that build up in the blood when the kidneys are not functioning properly. Abnormalities in these lab test results indicate decreased kidney function. Urinalysis can also look for protein in the urine, which is a sign of damaged kidneys [1].
Imaging such as x-rays, ultrasound, or CT scans allow vets to visualize the kidneys and look for any anatomical abnormalities, stones, cysts, or tumors. These diagnostic images help determine if there are any underlying issues contributing to the kidney dysfunction [2].
Treatment
There are several components to treating worsening kidney disease in cats:
Fluid therapy: Administering subcutaneous or intravenous fluids can help flush toxins from the body and maintain hydration. Fluids may be given at home or during vet visits. The frequency depends on the cat’s kidney values and overall health. Frequent at-home fluid therapy can prolong survival in cats with chronic kidney disease. (VCA Animal Hospitals)
Dietary changes: Special kidney diets restrict phosphorus and provide nutritional support. Reducing phosphorus intake is important, as diseased kidneys cannot properly excrete it. Veterinarians may recommend prescription kidney diets or additives to limit phosphorus. (PetMD)
Phosphate binders: Medications like aluminum hydroxide, calcium carbonate, or lanthanum carbonate can further reduce blood phosphorus levels. Phosphate binders are often used along with kidney diets. (Cornell Feline Health Center)
Anti-nausea medication: Medications like maropitant help control nausea and vomiting, common symptoms of kidney disease. Controlling these symptoms helps maintain appetite and hydration status. (PetMD)
Prognosis
The prognosis for cats with chronic kidney disease depends on the stage of the disease. In general, the earlier kidney disease is caught, the better the prognosis.
For cats in stage 1 or 2 kidney disease, the prognosis is often good with appropriate treatment and management. These cats can live for years with a good quality of life. According to the VCA, with treatment, stage 1 cats have an average survival time of 2 years and stage 2 cats have an average survival time of 15 months.1
The prognosis declines rapidly once a cat reaches stage 3 kidney disease. At this stage, clinical signs like vomiting, weight loss, and poor appetite often emerge. The VCA cites an average survival time of 7 months for stage 3 cats.1
Cats with stage 4 kidney disease have the worst prognosis. These cats are often quite ill and may require hospitalization. Median survival times are often measured in weeks or months at this stage. One study found a median survival time of just 35 days for cats starting in stage 4 kidney failure.2
As the disease progresses, cats experience a declining quality of life. Providing appropriate supportive care and pain management is important to keep cats comfortable at end of life. Euthanasia may be considered when a cat’s quality of life declines to an unacceptable level.
Prevention
There are several steps cat owners can take to help prevent kidney disease in their cats or slow the progression of existing kidney problems:
Annual veterinary exams and routine blood and urine tests are important for early detection of kidney issues, according to the ASPCA. Cats often hide symptoms until disease has progressed, so screening healthy cats can find problems sooner when treatment is more effective.
Managing risk factors like obesity, dental disease, high blood pressure, toxins, and other chronic illnesses can reduce further kidney damage. Getting regular dental cleanings, avoiding toxic plants, and keeping cats at a healthy weight are proactive steps owners can take.
Special kidney-healthy diets, medications, phosphorus binders, and intravenous fluids can all help support remaining kidney function. Consulting a vet to create a tailored treatment plan allows for the best possible prognosis.
While kidney disease cannot be fully prevented, attentive pet parents and proactive veterinary care give cats the best chance at early intervention and better quality of life. Annual screening, weight control, dental care, and avoiding toxins are key prevention strategies cat owners can implement.
