Chronic Kidney Disease in Cats: Stages and Bloodwork Explained
Chronic kidney disease (CKD) in cats is a progressive condition where kidneys gradually lose function. Staged using creatinine and SDMA levels, early detection allows better long-term management.
Kidney disease is one of the most common health problems in older cats. If your cat has been diagnosed with chronic kidney disease (CKD), you may be wondering what it means, how it's staged, and what tests are needed to monitor it. This guide explains the basics of CKD, common symptoms, the role of bloodwork, and how vets track progression over time.
What Is Chronic Kidney Disease in Cats?
The kidneys filter waste products from the blood and help maintain hydration, electrolytes, and red blood cell production. In chronic kidney disease, the kidneys slowly lose function over time. CKD is progressive, but with early detection and good management, many cats live for years after diagnosis.
Key Facts About CKD in Cats:
- Prevalence: Affects 1 in 3 cats over 12 years old
- Nature: Progressive, irreversible condition
- Early detection: Often no symptoms in early stages
- Management: Treatment can slow progression and maintain quality of life
- Prognosis: Varies greatly depending on stage and management
Symptoms of Chronic Kidney Disease
Some cats show no signs in the early stages. As the disease progresses, symptoms may include:
- • Increased drinking and urination: Often the first noticeable sign
- • Weight loss: Despite maintaining or increasing appetite initially
- • Decreased appetite: More common in advanced stages
- • Vomiting or nausea: Due to toxin buildup
- • Poor coat quality: Dull, unkempt appearance
- • Lethargy or weakness: From anemia and toxins
- • Bad breath: Ammonia-like odor from uremic toxins
- • Dehydration: Despite increased water intake
Bloodwork and Lab Tests for CKD
Blood and urine tests are key to diagnosing and staging kidney disease. The most important values include:
Key Laboratory Values:
- • Creatinine: Rises when kidneys can't filter waste efficiently
- • BUN (Blood Urea Nitrogen): Another waste product that builds up in the blood
- • SDMA: Often increases earlier than creatinine, helping detect CKD sooner
- • Phosphorus: High levels are linked to disease progression and poor outcomes
- • Urine Specific Gravity (USG): Shows how concentrated the urine is (low in CKD)
For detailed explanations of these values and their normal ranges, see our comprehensive guide on cat kidney values.
Want to track your cat's kidney values over time?
Use VetLens to monitor your cat's creatinine, BUN, SDMA, and phosphorus levels, and see how they change with treatment.
Try VetLens FreeStages of Kidney Disease in Cats
Vets often use the IRIS staging system (International Renal Interest Society) to classify CKD:
CKD Stages at a Glance
Early
No symptoms
Mild
More drinking
Moderate
Weight loss
Severe
Critical care
Stage 1
Creatinine <1.6
Stage 2
Creatinine 1.6-2.8
Stage 3
Creatinine 2.9-5.0
Stage 4
Creatinine >5.0
IRIS Staging System Details:
Normal bloodwork but subtle urine changes. Creatinine <1.6 mg/dL, SDMA <18 μg/dL. Usually no symptoms visible to owners.
Mild elevations in kidney values. Creatinine 1.6-2.8 mg/dL, SDMA 18-25 μg/dL. May start seeing increased drinking and urination.
Moderate kidney dysfunction. Creatinine 2.9-5.0 mg/dL, SDMA 26-38 μg/dL. Weight loss, nausea, and dehydration become apparent.
Severe kidney failure. Creatinine >5.0 mg/dL, SDMA >38 μg/dL. Requires intensive supportive care and comfort-focused treatment.
Staging helps guide treatment decisions and provides insight into prognosis.
Treatment and Management
There is no cure for CKD, but treatment can slow progression and improve quality of life. Management may include:
Dietary Management:
- • Prescription kidney diets (lower phosphorus and controlled protein)
- • Increased water intake to support hydration
- • Omega-3 fatty acid supplements
Medications:
- • Anti-nausea medications (maropitant, mirtazapine)
- • Blood pressure medications (ACE inhibitors)
- • Phosphate binders to control phosphorus levels
- • Potassium supplementation if levels are low
- • Medications for anemia (erythropoiesis-stimulating agents)
Supportive Care:
- • Subcutaneous fluids to help maintain hydration
- • Regular bloodwork to monitor progression and adjust treatment
- • Management of concurrent conditions (like hyperthyroidism)
Monitoring and Follow-Up Care
Regular Monitoring Includes:
- • Blood chemistry panels: Every 3-6 months (more frequently if unstable)
- • Complete blood count: Monitor for anemia and other changes
- • Urinalysis: Check for protein loss and infections
- • Blood pressure checks: Hypertension is common with CKD
- • Weight and body condition: Track nutrition status
- • Quality of life assessment: Adjust treatment as needed
Prognosis and Life Expectancy
How long a cat can live with CKD depends on several factors:
- • Stage at diagnosis: Earlier stages have better long-term outcomes
- • Response to treatment: Cats that respond well to kidney diets and medications do better
- • Concurrent diseases: Hyperthyroidism, dental disease, and other conditions affect prognosis
- • Owner compliance: Consistent treatment and monitoring improve outcomes
Typical Survival Times:
- Stage 1-2: Often years with good quality of life
- Stage 3: Months to 2-3 years with appropriate management
- Stage 4: Weeks to months, focus on comfort care
*Individual outcomes vary significantly based on response to treatment
Living with a CKD Cat
- • Ensure fresh water is always available
- • Stick to prescribed kidney diet (even if your cat is initially reluctant)
- • Give medications consistently as prescribed
- • Monitor for changes in appetite, drinking, or urination
- • Keep follow-up appointments for bloodwork
- • Consider subcutaneous fluid administration at home if recommended
- • Focus on maintaining quality of life
Related Reading
- • Cat Kidney Values Explained – detailed guide to understanding kidney bloodwork
- • Cat CBC Explained – understanding complete blood counts in CKD monitoring
- • Methimazole for Cats – hyperthyroidism and CKD often overlap in older cats
Track Your Cat's Kidney Health with VetLens
Cats with CKD require repeated bloodwork and close monitoring. With VetLens, you can:
- ✓ Upload and trend creatinine, BUN, SDMA, and phosphorus over time
- ✓ See plain-English explanations of each value
- ✓ Track symptoms alongside lab results
- ✓ Share organized updates with your veterinarian
Frequently Asked Questions
Can chronic kidney disease be reversed in cats?
No, CKD cannot be reversed or cured. However, progression can often be slowed significantly with appropriate treatment, and many cats maintain good quality of life for months to years after diagnosis.
Should I force my cat to eat the prescription kidney diet?
Kidney diets are very important for slowing disease progression, but forcing food can create food aversions. Work with your vet on transition strategies and appetite stimulants if needed.
How often does my cat with CKD need bloodwork?
This depends on the stage and stability. Early stages may need monitoring every 3-6 months, while advanced cases or cats starting new treatments may need monthly checks initially.
Is it normal for my cat with CKD to drink so much water?
Yes, increased drinking (polydipsia) and urination are hallmark signs of CKD. The damaged kidneys cannot concentrate urine normally, leading to increased water needs.