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What Stage Is My Dog’s CKD? — IRIS Staging and Stage-Specific Management
KidneyQ&AMeongsiljang Veterinary Advisory Board
The IRIS staging system for chronic kidney disease in dogs is essential for accurately understanding the progression of the disease. Here’s a summary of the key information every pet owner should know.
The IRIS Staging System Defines the Progression of Chronic Kidney Disease in Dogs
- IRIS Staging System: This internationally recognized framework, developed by the International Renal Interest Society (IRIS), helps us assess the severity of chronic kidney disease. Rather than just looking at raw numbers, it organizes the progression of the disease into stages, serving as a key tool to guide management strategies.
- Creatinine Levels: The concentration of creatinine in the blood is a primary indicator reflecting reduced kidney filtration function and plays a central role in determining the disease stage.
- SDMA Levels: Recent IRIS guidelines incorporate SDMA alongside creatinine for staging. This helps us detect changes in kidney function more accurately, particularly in cases where muscle loss might otherwise mask the true extent of renal impairment.
- Proteinuria Levels: The amount of protein excreted in the urine (UPC) is not a staging category itself but serves as a substage classification within each stage. It acts as a supplementary indicator to evaluate the degree of kidney damage.
- Stage-Specific Management Strategies: Symptoms and management approaches vary significantly from Stage 1 to Stage 4, making accurate classification the essential first step in care. We closely monitor for any changes in stage through regular check-ups.
IRIS Staging Is Based on the Degree of Reduced Kidney Function and Proteinuria Levels
- Kidney Function Assessment: The IRIS staging system classifies the degree of reduced kidney filtration into stages 1 through 4, based on blood creatinine (and SDMA) levels measured repeatedly while the patient is stable, fasted, and not dehydrated.
- Subclassification Indicators: Proteinuria (UPC) and blood pressure are not used to determine the stage itself but serve as criteria for subclassifying (substaging) within each stage.
- Stage Determination Criteria: The stage is determined by creatinine and SDMA levels, while proteinuria and blood pressure are used to add subclassification, allowing for a comprehensive assessment of the patient’s condition.
- Developing Management Strategies: Accurate classification is essential because the required supplements, medications, and dietary adjustments vary depending on the stage and subclassification.
- Regular Monitoring Required: Diagnosis is not a one-time event. To track stage changes with your veterinarian, repeated measurements must be taken when the patient is stable and not dehydrated or in uremic crisis. Regular check-ups are crucial to ensure no changes are missed.
IRIS Staging Is Divided Into Four Stages, Each With Distinct Characteristics
- Stage 1: This is the early stage of non-azotemia (creatinine levels are within the normal range), where other kidney abnormalities such as reduced concentrating ability, imaging or palpation abnormalities, and persistent proteinuria are confirmed. Most pets do not show obvious symptoms.
- Stage 2: This is the stage where mild azotemia begins, and reduced urine concentration or proteinuria may appear.
- Stage 3: Azotemia progresses to moderate to severe levels, and systemic (uremic) symptoms such as vomiting, decreased appetite, and dehydration start to appear.
- Stage 4: This is the stage of severe loss of kidney function, where uremic symptoms become pronounced, and active treatment is necessary to sustain life.
- Differences by Stage: Management methods and prognosis vary significantly depending on the stage, so accurate classification is key to treatment. Work closely with your veterinarian to carefully monitor changes in the stage.
Comparison Table of IRIS Staging Criteria
| Item | Creatinine (mg/dL, dogs) | Proteinuria substaging (UPC) | Main features |
|---|---|---|---|
| Stage 1 | < 1.4 | Applied across all stages: non-proteinuric <0.2 / borderline 0.2–0.5 / proteinuric >0.5 | Non-azotemic, presence of other renal abnormalities (usually no symptoms) |
| Stage 2 | 1.4–2.8 | Applied across all stages: non-proteinuric <0.2 / borderline 0.2–0.5 / proteinuric >0.5 | Mild azotemia, few or mild symptoms |
| Stage 3 | 2.9–5.0 | Applied across all stages: non-proteinuric <0.2 / borderline 0.2–0.5 / proteinuric >0.5 | Moderate to severe azotemia, systemic symptoms begin |
| Stage 4 | > 5.0 | Applied across all stages: non-proteinuric <0.2 / borderline 0.2–0.5 / proteinuric >0.5 | Severe loss of kidney function, severe uremic symptoms |
UPC: urine protein/creatinine ratio. Creatinine values are IRIS decision thresholds and may vary by laboratory and individual. Proteinuria (UPC) and blood pressure are not stages themselves but substaging criteria that further divide within each stage; in dogs, UPC is classified as non-proteinuric <0.2, borderline 0.2–0.5, and proteinuric >0.5.
IRIS Staging Helps Predict Disease Progression and Establish Treatment Plans
- Prognostic Staging: The IRIS classification serves as a crucial benchmark for predicting the progression rate of the disease.
- Personalized Treatment: Since the required medications, nutritional supplements, and dietary adjustments vary by stage, tailored management is possible.
- Setting Treatment Goals: The focus is on prevention in stages 1–2, while symptom relief and life extension become the primary goals in stages 3–4.
- Collaboration with Your Veterinarian: We continuously refine the treatment plan through regular check-ups and open communication.
- Success in Long-Term Care: Accurate staging directly impacts the improvement of long-term quality of life. Consistent monitoring ensures no changes in disease stage are overlooked.
Stages 3–4 Require Immediate Veterinary Care
IRIS stage 3 or higher indicates severely compromised kidney function. Symptoms such as vomiting, loss of appetite, dehydration, and lethargy may occur, so immediate veterinary care is essential. Management at this stage is critical for extending life.
IRIS Staging Should Be Confirmed Through Regular Testing
- Regular check-ups are essential: IRIS staging isn’t a one-time assessment; it requires ongoing monitoring.
- Blood and urine tests: Regularly check creatinine levels and proteinuria to track changes in disease stage.
- Individual differences matter: Disease progression varies among dogs, so be sure to follow the testing schedule recommended by your veterinarian.
- Early detection is key: Quickly identifying stage changes allows for timely intervention.
- Maximize treatment effectiveness: Regular monitoring enhances treatment outcomes and improves prognosis. Consistent care is the cornerstone of long-term health.
Management Strategies Vary According to IRIS Stage
- Stages 1–2 Management: A renal prescription diet restricted in phosphorus is recommended (especially from Stage 2 onward). Rather than strictly reducing protein, adjust it to an appropriate level and restrict it only when uremia is present.
- Stage 3 and Beyond: Medications and supportive therapies are necessary, including phosphate binders, fluid therapy, and management of anorexia and uremia.
- Phosphorus and Electrolyte Management: CKD can be accompanied by hyperphosphatemia, hypokalemia, and metabolic acidosis. These should be managed together according to the target phosphorus levels for each disease stage.
- Nutritional Support: Provide customized supplementation of nutrients required for each stage through renal diets and supplements.
- Veterinary Consultation: Continuously communicate with your veterinarian to adjust the management strategy as needed.
- Daily Care: Prevent dehydration by ensuring adequate water intake, and flexibly adjust activity levels and environmental conditions according to the disease stage.
Reviewed by a veterinarian
Dr. Tony — Punnawat Phongkittirak
VeterinarianA veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.
Frequently Asked Questions
Why is the IRIS staging classification important?
The IRIS staging system is essential for accurately determining the stage of disease progression and developing a tailored management plan. Early detection and appropriate care help improve your pet’s long-term quality of life.
How do I determine the IRIS stage classification?
We measure creatinine (and SDMA) levels through blood tests and check for proteinuria (UPC) via urine tests. However, accurate staging can be challenging in cases of dehydration or uremic crisis, so we repeat the measurements once the patient is stable. The veterinarian will then determine the stage and subclassification by evaluating all the indicators together.
Are you worried even though the IRIS staging is stage 1?
Stage 1 is the early phase of non-azotemic kidney disease, but early management is crucial. Dietary adjustments and regular check-ups can help slow the progression of the disease. Following your veterinarian’s advice is the safest approach.
Does the IRIS staging classification progress quickly?
The progression of chronic kidney disease varies greatly from one pet to another. Dietary management, medication, and regular check-ups can help slow its progression. Work with your veterinarian to create a tailored management plan.
If a pet is classified as Stage 4 according to the IRIS staging system, how long can they be expected to live?
Stage 4 is the most severe stage. However, the progression rate of CKD varies greatly among individual dogs, making it difficult to provide a uniform survival period. Rather than focusing on an exact timeframe, it is important to concentrate on maintaining quality of life through appropriate management, such as fluid therapy, diet, and medication, and to work with your veterinarian to find the best course of action.
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References
[2] Björnsdóttir, H. et al. (2021). Evaluation of IRIS staging criteria in dogs with chronic kidney disease. Journal of Veterinary Internal Medicine, 35(4), 1892–1900.
[3] Klein, A. et al. (2020). Clinical utility of the IRIS staging system in canine chronic kidney disease: a prospective cohort study. Veterinary Record, 187(12), 456.