International Renal Interest Society: Canine CKD Guidelines

The mission of Dr. Rosie DVM is to help pet owners and veterinary practitioners diagnose, understand, and treat kidney disease in dogs and cats. One of our main goals is to explain the guidelines of the International Renal Interest Society (IRIS), the internationally recognized standard for diagnosing, staging, and treating kidney disease in small animals.

Kidney disease can be sudden in onset (acute kidney injury, or AKI) or long-standing and progressive (chronic kidney disease, or CKD). IRIS publishes a staging system and treatment recommendations for CKD, a grading system for AKI, and consensus recommendations for dogs with proteinuric kidney disease. These guidelines are reviewed and updated regularly by the IRIS Board as new evidence becomes available, and the current official versions are published on the IRIS website.

IRIS Staging of CKD in Dogs (Modified 2026)

As a leader in veterinary nephrology, IRIS provides practicing veterinarians with evidence-based guidance for diagnosing, treating, and managing kidney disease, including how to interpret diagnostic results. The values on this page follow the IRIS staging guidelines and canine treatment recommendations as modified in 2026.

Staging CKD is essential for choosing appropriate treatment and monitoring. Staging is based on fasting blood creatinine, fasting blood SDMA, or preferably both, measured on at least two occasions in a stable, well-hydrated patient. The patient is then substaged by proteinuria and by systemic blood pressure. These stages allow veterinarians to apply treatment recommendations and to predict the likely response to treatment based on clinical experience.

The inclusion of symmetric dimethylarginine (SDMA) in the IRIS staging guidelines was a significant advance, both for the early diagnosis of CKD and for tailoring treatment to the individual patient. The IRIS Board recommends measuring both blood creatinine and SDMA, because these two markers of kidney function complement each other. IRIS has also revised the canine stages, widening Stage 2 and narrowing Stage 3, to reduce the wide variation in clinical signs and treatment needs seen among dogs previously grouped in the larger Stage 3.

The canine stages are:

  • Stage 1: blood creatinine less than 1.4 mg/dL (less than 125 µmol/L); SDMA less than 18 µg/dL. The dog is not azotemic, but some other kidney abnormality is present, such as inadequate urine concentrating ability without a non-renal cause, abnormal kidney palpation or imaging findings, persistent proteinuria of renal origin, abnormal kidney biopsy results, or creatinine or SDMA values rising over serial samples.
  • Stage 2: blood creatinine 1.4 to 2.8 mg/dL (125 to 250 µmol/L); SDMA 18 to 35 µg/dL. Creatinine is normal or mildly increased and azotemia is mild. Clinical signs are usually mild or absent.
  • Stage 3: blood creatinine 2.9 to 5.0 mg/dL (251 to 440 µmol/L); SDMA 36 to 54 µg/dL. Moderate renal azotemia. Many signs outside the kidney may be present, and their extent and severity vary.
  • Stage 4: blood creatinine above 5.0 mg/dL (above 440 µmol/L); SDMA above 54 µg/dL. There is an increasing risk of systemic clinical signs and uremic crises.

SDMA refines these stages. A persistently increased SDMA above 14 µg/dL suggests reduced kidney function and may be used to diagnose early CKD in a dog whose creatinine is still below 1.4 mg/dL. SDMA is less affected than creatinine by loss of muscle mass, so when the two markers disagree, IRIS recommends staging and treating the dog at the higher stage:

  • A dog with creatinine below 1.4 mg/dL and SDMA persistently above 18 µg/dL is staged and treated as Stage 2.
  • A dog with creatinine of 1.4 to 2.8 mg/dL and SDMA persistently above 35 µg/dL is staged and treated as Stage 3.
  • A dog with creatinine of 2.9 to 5.0 mg/dL and SDMA persistently above 54 µg/dL is staged and treated as Stage 4.

Substaging by Proteinuria

Proteinuria is assessed with the urine protein-to-creatinine ratio (UPC), after ruling out urinary tract inflammation and hemorrhage, and confirmed on repeated samples. In dogs:

  • Non-proteinuric: UPC less than 0.2
  • Borderline proteinuric: UPC 0.2 to 0.5
  • Proteinuric: UPC greater than 0.5

Substaging by Blood Pressure

Systolic blood pressure is classified by the risk of damage to target organs such as the kidneys, eyes, brain, and heart:

  • Normotensive: less than 140 mmHg, minimal risk
  • Prehypertensive: 140 to 159 mmHg, low risk
  • Hypertensive: 160 to 179 mmHg, moderate risk
  • Severely hypertensive: 180 mmHg or higher, high risk

IRIS Treatment Recommendations for CKD in Dogs

Individualized treatment is crucial in managing CKD. The IRIS recommendations are a starting point for most dogs at each stage. Regular monitoring is essential, and treatment should be adjusted according to each patient's response.

Some suggested treatments are not approved for use in dogs in every region, and the recommended dosage rates are therefore based on clinical experience rather than official authorization. Veterinarians must make a risk-benefit assessment for each patient before starting any treatment.

In summary, the recommendations by stage are:

  • All stages: stop any drugs that could damage the kidneys, identify and treat pre-renal and post-renal problems, rule out treatable conditions such as pyelonephritis and ureteral obstruction with radiographs or ultrasound, make sure fresh water is always available, correct dehydration promptly with fluids, and measure blood pressure and UPC.
  • Stage 1: as above. Treat persistent hypertension and proteinuria as described below, and monitor for progression.
  • Stage 2: as for Stage 1, and consider a clinical kidney diet, which is easier to introduce before the appetite declines. Aim to keep blood phosphate between 2.7 and 4.6 mg/dL (0.9 to 1.5 mmol/L), adding an intestinal phosphate binder if diet alone does not achieve this. Treat anemia caused by CKD when the hematocrit is below 30%, or when it stays between 30% and 35%. In a well-hydrated Stage 2 dog, anemia below 30% is less likely to be caused by CKD alone, so other causes should be looked for first. Treat vomiting and nausea with anti-nausea drugs such as maropitant or ondansetron, and poor appetite or weight loss with appetite stimulants such as capromorelin or mirtazapine. If muscle loss is marked, consider staging on SDMA rather than creatinine.
  • Stage 3: as for Stage 2, feeding a clinical kidney diet, with a more realistic phosphate target of below 5.0 mg/dL (1.6 mmol/L). Correct metabolic acidosis when blood bicarbonate or total carbon dioxide is below 18 mmol/L, aiming to keep it between 18 and 24 mmol/L. Some dogs need routine fluids to stay hydrated, a feeding tube should be considered if appetite drugs do not work, and doses of drugs cleared by the kidneys may need adjusting.
  • Stage 4: as for Stage 3, with a phosphate target of below 6.0 mg/dL (1.9 mmol/L). Intensify efforts to prevent malnutrition and dehydration, for example with a feeding tube, and consider dialysis or kidney transplantation.

IRIS recommends investigating any dog with a UPC above 0.5 for the underlying cause, and treating confirmed, persistent renal proteinuria with an angiotensin receptor blocker (ARB) and a clinical kidney diet. Adding an ACE inhibitor when proteinuria is not controlled should be done cautiously, ideally with advice from a veterinary nephrologist. Clopidogrel, or low-dose aspirin if clopidogrel is not available, can be considered to reduce the risk of blood clots. The aim is the lowest UPC that can be reached without causing harm. Many dogs with primary glomerular disease cannot reach a UPC below 0.5, and for them the goal is a 50% reduction from the starting value. Dogs with borderline proteinuria (UPC 0.2 to 0.5) need close monitoring.

Antihypertensive treatment is recommended when systolic blood pressure persistently exceeds 160 mmHg on repeated measurements, or straight away when there is evidence of target organ damage, with the goal of bringing it gradually below 160 mmHg. The stepwise approach in dogs is an ACE inhibitor such as benazepril, then doubling its dose, then adding the calcium channel blocker amlodipine (especially in severely hypertensive dogs), and then adding an ARB such as telmisartan, or hydralazine, if more treatment is needed. A systolic pressure below 120 mmHg, or signs such as weakness or a fast heart rate, indicates low blood pressure, which should be avoided.

IRIS Grading of Acute Kidney Injury (AKI)

Acute kidney injury covers a spectrum of kidney damage, from mild, clinically undetectable loss of nephrons to severe acute kidney failure. IRIS recommends grading AKI to assess its severity accurately and to reflect its nature as a continuum. The IRIS AKI grading scale (Grades I to V) for dogs and cats is based on fasting blood creatinine concentration together with clinical findings, including urine production:

  • Grade I: blood creatinine less than 1.6 mg/dL (less than 140 µmol/L). Non-azotemic AKI, documented by historical, clinical, laboratory, or imaging evidence, by oliguria or anuria, or by a progressive increase in blood creatinine of 0.3 mg/dL (26.4 µmol/L) or more within 48 hours, still within the non-azotemic range.
  • Grade II: blood creatinine 1.7 to 2.5 mg/dL (141 to 220 µmol/L). Mild AKI, with documented AKI and static or progressive azotemia.
  • Grade III: blood creatinine 2.6 to 5.0 mg/dL (221 to 439 µmol/L). Moderate to severe AKI with increasing severity of azotemia and kidney failure.
  • Grade IV: blood creatinine 5.1 to 10.0 mg/dL (440 to 880 µmol/L).
  • Grade V: blood creatinine above 10.0 mg/dL (above 880 µmol/L).

Each grade is further subgraded as oliguric or anuric versus non-oliguric, and by whether the patient requires renal replacement therapy, such as dialysis.

This grading system was developed under the leadership of Dr. Larry Cowgill of the IRIS Board. It was provisionally adopted in 2012 and formally adopted in 2013, with input from the American and European Societies of Veterinary Nephrology and Urology (ASVNU and ESVNU) and the wider veterinary community. The AKI grading scheme helps veterinarians establish an appropriate prognosis for patients with AKI and complements the IRIS guidelines for staging and treating CKD.

Treatment of Canine Proteinuric Kidney Disease

At its 2011 meeting in Denver, the IRIS Board established a study group to write a consensus report titled "Best Clinical Practices for Proteinuric Kidney Disease in Dogs." Dr. David Polzin and Dr. Larry Cowgill, both Board members, co-chaired the group. Its goal was to use the available evidence and expert consensus to produce practical recommendations for diagnosing and managing these patients.

To address the wide range of patient presentations and regional differences, the study group developed focused recommendations on the following topics:

  • Diagnostic investigation of dogs with suspected glomerular disease
  • Standard therapy for dogs with suspected glomerular disease
  • Immunosuppressive treatment for dogs with glomerular disease based on established pathology
  • Immunosuppressive treatment for dogs with proteinuric kidney disease in the absence of a histopathologic diagnosis
  • Immunosuppressive treatment for dogs with suspected glomerular disease and serologic evidence of a possible causative agent

The results were published in 2013 as a supplement to the Journal of Veterinary Internal Medicine, which is available online. The IRIS Board intended the project to serve as a template for future consensus recommendations in nephrology and other fields of veterinary medicine. The report and its publication as a journal supplement were supported by Novartis Animal Health, now part of Elanco Animal Health.

When to Talk to Your Veterinarian

If your dog has been diagnosed with kidney disease, ask your veterinarian which IRIS stage and substages apply, which treatments are recommended for that stage, and how often bloodwork, urine testing, and blood pressure should be rechecked. Contact your veterinarian promptly if your dog drinks or urinates much more than usual, loses appetite or weight, vomits, or seems lethargic.