The 4 Stages of Kidney Disease Your Cat Can’t Afford to Miss


Kidney disease is a common condition in cats, especially as they age. In fact, some studies estimate that around 30-40% of cats over 10 years old may have some degree of kidney disease.

Kidney disease happens when the kidneys become damaged and can no longer effectively filter waste products from the blood. This allows toxins, minerals, and fluids to build up in the body, causing symptoms like increased thirst/urination, weight loss, poor appetite, vomiting, and more.

Catching kidney disease early and managing it appropriately is crucial. Without proper treatment and diet management, kidney disease typically progresses through four stages, eventually leading to kidney failure and death. However, with early detection and proper care, many cats with kidney disease can live comfortably for years before reaching the later stages.

Stage 1 Kidney Disease

Stage 1 kidney disease in cats is the earliest stage of chronic kidney disease (CKD). At this point, cats usually do not show any outward symptoms of kidney disease. However, some subtle changes may be happening inside the body.

The kidneys have lost some ability to concentrate urine, so cats may drink and urinate more frequently. However, these signs are often missed by pet owners. Blood and urine tests may show slightly elevated kidney values like creatinine or BUN, but these may still be within normal ranges (Hill’s Pet Nutrition).

Since stage 1 CKD often has no symptoms, it is usually diagnosed incidentally through routine bloodwork and urinalysis. Annual senior wellness screening is important to detect early kidney disease in cats.

Treatment in stage 1 aims to support kidney function and slow further progression of CKD. Vets may prescribe medications like ACE inhibitors to control blood pressure and maintain adequate blood flow to the kidneys. Dietary changes to prescription kidney diets can help reduce workload on the kidneys (VCA Animal Hospitals).

With early detection and proper management, many cats can live comfortably with stage 1 CKD for months to years before progressing to more advanced stages.

Stage 2 Kidney Disease

Stage 2 is considered early kidney disease. At this stage, the kidneys are not functioning optimally but the cat can still live a relatively normal life. Some key symptoms of stage 2 kidney disease in cats include:

  • Increased thirst and urination
  • Weight loss
  • Reduced appetite
  • Mild dehydration

On lab tests, a cat with stage 2 kidney disease will have a creatinine level between 1.6-2.8 mg/dL and a BUN level of 30-65 mg/dL. The specific gravity of the urine will be more dilute than normal, usually 1.015 or lower.

Treatment recommendations for stage 2 kidney disease typically include:

  • Prescription kidney diets reduced in phosphorus and protein
  • Subcutaneous fluids to prevent dehydration
  • Medications to control blood pressure and acidity
  • Supplements such as omega-3 fatty acids, antioxidants, and B-vitamins

With prompt veterinary care and proper management at home, cats with stage 2 kidney disease can live normal lifespans.

Stage 3 Kidney Disease

Stage 3 kidney disease in cats is considered moderate or mid-stage kidney failure. At this point, approximately 50-75% of functional kidney tissue has been lost [1]. Some symptoms that may be observed include:

  • Increased thirst and urination
  • Weight loss
  • Reduced appetite
  • Vomiting or nausea
  • Bad breath
  • Lethargy

Lab tests typically show elevated levels of creatinine (between 2.9-5.0mg/dL), BUN, and phosphorus. Abnormally low urine specific gravity may also be noted. Anemia is common due to declining red blood cell production [2].

Treatment focuses on managing clinical signs through dietary changes, supplements, intravenous fluids, anti-nausea medications, phosphate binders, and medications to control anemia. Regular monitoring is required to track progression of the disease.

Stage 4 Kidney Disease

Stage 4 kidney disease is considered end-stage kidney failure. At this point, the kidneys have lost about 3/4 of their function. Symptoms tend to be more severe in stage 4 and can include:

  • Severe vomiting and diarrhea
  • Complete loss of appetite
  • Significant weight loss
  • Lethargy and depression
  • Dehydration
  • Anemia
  • Mouth ulcers

Lab tests often show high levels of waste products like creatinine and BUN in the blood, indicating the kidneys’ inability to filter them out properly. Low red blood cell counts and low blood protein levels are also common.

Treatment focuses on managing symptoms and slowing further kidney decline. This includes IV fluids, medications, dietary changes, and phosphate binders. Dialysis is sometimes used, but kidney transplants are rarely an option for cats. Even with treatment, most cats with stage 4 kidney disease only live a few weeks to months [1]. Providing the best quality of life is the main goal at this stage.

Diagnosing Kidney Disease

There are several tests veterinarians use to diagnose kidney disease in cats:

Blood tests – Blood tests allow vets to measure levels of waste products like creatinine to see if kidneys are functioning properly. Elevated creatinine levels indicate reduced kidney function.

Urine tests – A urine test looks for high levels of protein, which is a sign of kidney damage. Urine specific gravity is measured to see how well the kidneys are concentrating urine.

Blood pressure – High blood pressure damages kidneys over time, so vets will measure blood pressure as part of a kidney exam.

Imaging – X-rays and ultrasound allow vets to view the size, shape and texture of the kidneys. This reveals abnormalities indicating kidney disease.

Kidney biopsies – Taking a tissue sample from the kidney reveals damage and can help identify the underlying cause of the disease.

Annual blood and urine tests are recommended for senior cats to catch kidney disease early. Symptoms like increased thirst, weight loss, vomiting and bad breath are indicators to get a cat tested for kidney problems by a veterinarian.


Treating Kidney Disease

There are several treatment options available for cats with kidney disease, and early intervention is critical for the best prognosis. Some of the main treatments include:

Fluid therapy – Providing subcutaneous or intravenous fluids can help flush toxins from the body and support kidney function. This is often one of the first treatments recommended, especially for cats in more advanced stages of kidney disease. Fluid therapy helps prevent dehydration and maintain blood pressure (Cornell Feline Health Center).

Medications – Drugs like ACE inhibitors can help control high blood pressure and reduce strain on the kidneys. Antacids may be used to control ulcers. Iron supplements can treat anemia. Antibiotics are sometimes prescribed for urinary tract infections. Additional medications may provide pain relief, antinausea effects, phosphorus binders, and appetite stimulants (VCA Animal Hospitals).

Dietary changes – Special kidney diets are typically lower in protein and phosphorus to reduce waste buildup. Increased omega-3 fatty acids can help reduce inflammation. Changing to wet food increases water intake. Supplements provide key vitamins and nutrients (AVMA).

The earlier kidney disease is detected and treated, the better the prognosis. Cats who receive early intervention and maintain a good quality of life with treatment can live for many months to years with kidney disease. Working closely with a veterinarian to find the right combination of treatments is essential.

Diet and Nutrition

Cats with kidney disease often lose their appetite and have trouble maintaining their body weight. Feeding a diet designed for kidney health is important to support your cat’s remaining kidney function and overall health. According to VCAA, kidney support diets contain less protein, sodium, and phosphorus, and increased omega-3 fatty acids compared to regular adult cat food.

Some recommended prescription kidney diets include Hill’s Prescription Diet k/d and Royal Canin Veterinary Diet Renal Support. These foods come in both wet and dry formulations. Feeding wet food can help increase water intake. Homemade diets are not recommended unless formulated by a veterinary nutritionist due to the strict nutritional requirements.

Supplements like potassium gluconate and calcitriol may be recommended by your veterinarian. Phosphorus binders can also help maintain proper nutrient levels. Always follow your vet’s recommendations on supplements.

Tips for feeding cats with kidney disease include:

  • Feed smaller, more frequent meals
  • Warm up canned food to increase palatability
  • Add water to dry food to increase moisture intake
  • Avoid giving high sodium treats
  • Weigh your cat regularly to monitor weight changes

With the right diet and supplements tailored to your cat’s individual needs, you can help support kidney health and your cat’s wellbeing.

Outlook and Prognosis

The prognosis for cats with kidney disease varies depending on the stage and progression of the disease. In early stages (1 & 2), the prognosis can be good with appropriate treatment and management. However, as the disease advances, the prognosis worsens.

In stage 3 kidney disease, studies show average survival times of 18-24 months with treatment. But cats may live longer depending on response to therapy. With aggressive treatment, some cats can live years past initial diagnosis. Without any treatment, survival is much lower – around 2 to 4 months on average.

Once a cat reaches stage 4 kidney failure, the prognosis is grave. At this end stage, the kidneys have lost 75% or more of function. There are no treatments that can reverse this amount of damage. With intensive therapy, survival is approximately 2-12 months. Without treatment or fluid therapy, cats may only live weeks to a few months.

A major consideration for cats in late stage kidney disease is quality of life. As the disease progresses, cats often experience lethargy, poor appetite, weight loss, vomiting, diarrhea and other symptoms. Managing these effects is crucial for maintaining a good quality of life. Working closely with a veterinarian can help provide the best care as the disease advances.





There are some steps cat owners can take to help prevent kidney disease in their feline companions:

Feeding a high quality diet designed for kidney health can help reduce strain on the kidneys. Look for foods with reduced protein, phosphorus and sodium content. Increased omega-3 fatty acids from fish oil may also be beneficial. Always consult your veterinarian before making major diet changes.

Ensuring cats stay well-hydrated is crucial for kidney health. Provide fresh, clean water at all times and consider getting a cat fountain if your cat doesn’t drink enough. Canned food also has high moisture content.

Limit exposure to toxins like antifreeze, heavy metals, lilies, and NSAIDs as these can damage the kidneys. Keep cats indoors and supervise time outdoors.

Annual senior wellness exams allow vets to check kidney values and look for early signs of kidney disease through bloodwork and urinalysis. Catching it early provides the best chance for management and treatment.

Be aware of risk factors like age, genetics, dental disease, urinary tract infections, and obesity. Take steps to mitigate those risks.

While kidney disease can’t always be prevented, these measures can reduce risk and help avoid rapid progression when it does occur.

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