Introduction
Kidney disease is one of the most common chronic illnesses affecting cats. According to research, the prevalence of kidney disease in cats ranges from 1.18% to 3.05% in academic institutions and 1.9% in primary care veterinary clinics [1][2]. As cats age, they are at an increased risk for developing kidney disease. Overall, the prognosis depends on the stage of kidney disease and how early it is detected and treated. However, kidney disease often progresses over time and can lead to kidney failure if left untreated.
Stages of Kidney Disease
The IRIS staging system is commonly used to classify the progression of chronic kidney disease (CKD) in cats. It consists of 4 stages based on measurements of creatinine in the blood:
Stage 1: Creatinine less than 1.6 mg/dL. Often no symptoms present at this stage. Prognosis is generally good with treatment.
Stage 2: Creatinine 1.6-2.8 mg/dL. Mild symptoms may begin to appear such as increased thirst and urination. Prognosis is fair to good depending on response to treatment. Life expectancy can be years with proper management.
Stage 3: Creatinine 2.9-5.0 mg/dL. Symptoms become more noticeable such as vomiting, weight loss, poor appetite. Prognosis declines with more aggressive treatment needed. Life expectancy is months to a few years.
Stage 4: Creatinine over 5.0 mg/dL. Severe clinical signs present and cat is very ill. Prognosis is grave at this stage even with aggressive therapy. Life expectancy is weeks to months in most cats.
Treatment is aimed at slowing progression of CKD, managing symptoms, and maintaining quality of life. The earlier CKD is caught, the better the outcome generally is. Monitoring lab work and clinical signs at each stage is important for guiding management of this progressive disease.
Diagnosis
There are several tests veterinarians use to diagnose kidney disease in cats:
Blood tests – Bloodwork allows vets to measure levels of substances like blood urea nitrogen (BUN) and creatinine to assess kidney function. Elevated BUN and creatinine indicate the kidneys are not properly filtering waste products from the blood. Other abnormalities may point to anemia and electrolyte imbalances resulting from kidney disease.
Urinalysis – Analyzing a urine sample can reveal important indicators of kidney health like protein levels and specific gravity. Persistent protein in the urine often signals deteriorating kidney function. Urine specific gravity outside the normal range may indicate improper urine concentration.
Imaging – X-rays, ultrasound, or CT scans of the abdomen can identify issues like small, shrunken kidneys, abnormalities, stones, or masses that may be contributing to kidney disease. These imaging techniques allow visualization of the kidneys to fully assess their structure and function.
Overall, bloodwork and urinalysis are the primary diagnostic methods. Medical imaging provides additional visualization of the kidneys when needed.
Treatment
The main treatments for cats with kidney disease include diet modification, intravenous fluids, and medications. The goal of treatment is to slow the progression of kidney failure, manage clinical signs, and maintain quality of life.
Diet is a critical part of managing kidney disease in cats. Special renal diets are restricted in phosphorus and protein to reduce strain on the kidneys. Increased omega-3 fatty acids and antioxidants support kidney health. Feeding canned food also encourages hydration. Vets may recommend prescription renal diets or over-the-counter options.
Fluid therapy replenishes hydration and flushes waste from the kidneys. Subcutaneous fluids can be given at home under the skin. Hospitalization for intravenous fluids may be needed during acute kidney injury or advanced disease.
Medications help control signs of kidney failure. Anti-nausea drugs can treat vomiting and appetite stimulants target poor appetite. Antacids manage ulcers and gastrointestinal problems. Potassium and phosphorus binders minimize mineral imbalances. Blood pressure medications are sometimes prescribed.
Stage 1
Stage 1 kidney disease in cats is characterized by very mild symptoms that may go unnoticed by pet owners. At this stage, there is generally no significant loss of kidney function yet (Avon Vets). Common symptoms include:
- Increased thirst and urination
- Mild weight loss
- Changes in appetite
- Occasional vomiting or diarrhea
With early diagnosis and proper treatment, cats with stage 1 kidney disease typically have a survival time of 2-3 years or more past initial diagnosis. Kidney function can often be preserved at this stage through dietary changes, fluids, and medication (The Veterinary Nurse). Regular vet visits and bloodwork monitoring are recommended to catch any progression early. Overall the prognosis is good for cats diagnosed and managed at stage 1 kidney disease.
Stage 2
Cats diagnosed with stage 2 kidney disease typically show minor symptoms such as increased thirst and urination. Blood and urine tests at this stage usually show slightly elevated waste levels. With appropriate treatment and diet changes, cats in stage 2 can live a normal lifespan.
According to a 2017 study published in The Veterinary Nurse (https://www.theveterinarynurse.com/review/article/supporting-quality-of-life-in-feline-patients-with-chronic-kidney-disease), the median survival time for cats diagnosed with stage 2 kidney disease was 3.15 years (1151 days). However, some cats lived as long as 8.5 years following their diagnosis.
With prompt veterinary care, a properly formulated kidney diet, medications as needed, and attentive home care, many cats with stage 2 kidney disease can live comfortably for years after diagnosis.
Stage 3
Stage 3 of kidney disease indicates moderate loss of kidney function, with 30-59% of normal function remaining. The following are common symptoms cats may exhibit during stage 3 kidney disease, according to veterinary journal Veterinary Focus (https://www.veterinarypracticenews.com/staging-feline-renal-disease/):
- Increased thirst and urination
- Loss of appetite
- Weight loss
- Lethargy
- Mild dehydration
- Anemia
- Stomach ulcers
According to PetMD (https://www.petmd.com/cat/general-health/when-to-euthanize-cat-with-kidney-disease), cats diagnosed with stage 3 kidney disease have a median survival time of 1.86 years (679 days). However some cats can survive up to 5.75 years with careful management and treatment.
Stage 4
In stage 4 of kidney disease, the cat’s kidneys have lost about 75% or more of their functional capacity. This is considered end-stage kidney failure.[1] Key symptoms at this stage include[2]:
- Severe vomiting
- Extreme lethargy and weakness
- Loss of appetite
- Weight loss
- Mouth ulcers
- Seizures
- Coma
Cats in stage 4 kidney failure have a very poor prognosis. Studies show the median survival time for cats with stage 4 kidney disease is only 1.16 months or about 35 days.[3] With intensive veterinary treatment and dedicated home care, some cats can live 6 months or longer, but most cats will only live weeks to a few months once end-stage renal failure sets in.
Prognosis
The prognosis for cats with kidney disease depends on several factors, including the stage of the disease and the cat’s response to treatment. According to the Cornell University College of Veterinary Medicine, the prognosis is quite variable.1 In a study published in the Journal of Veterinary Internal Medicine, cats with stage 4 kidney disease had a median survival time of only 35 days.2
As the disease progresses to end-stage kidney failure, cats may experience anorexia, vomiting, and other symptoms that significantly impact their quality of life. Euthanasia may be considered when the cat’s quality of life declines to an unacceptable level. Owners should discuss prognosis, treatment options, and quality of life concerns with their veterinarian to make informed decisions about their cat’s care.
Conclusion
Kidney disease is a common condition that affects many older cats. While there is no cure, with early diagnosis and proper treatment, cats can still live quality lives for years after the initial diagnosis. The key is to have your vet regularly monitor your cat’s kidney function through bloodwork and urine testing, and to start medical management and dietary changes as soon as kidney disease is detected. This helps slow the progression of the disease and preserve kidney function for as long as possible.
The prognosis for kidney disease depends on the stage at diagnosis and how well the cat responds to treatment. Cats diagnosed in stage 1 or 2 can live 1-3 years or longer. Even cats diagnosed in stage 3 or 4 can live months to a year or more with dedicated care and monitoring. While kidney disease shortens a cat’s lifespan, there are many things you can do to keep your cat comfortable and happy during their remaining time.
The takeaway for cat owners is to have senior cats screened annually for kidney disease and be proactive if it is detected. With early intervention and dedicated at-home care, many cats can still live enjoyable lives for years after being diagnosed with kidney disease.
