Chronic kidney disease in dogs is usually described using IRIS stages. The stage helps your veterinarian estimate how advanced the disease is and decide what monitoring and treatment are appropriate. It is not a countdown clock, and dogs in the same stage can have very different outcomes.
How kidney disease is staged
The International Renal Interest Society (IRIS) staging system primarily uses blood creatinine, with SDMA sometimes helping refine the picture. Staging is done after dehydration and other temporary causes of abnormal kidney values have been addressed.
Dogs are also substaged based on blood pressure and the amount of protein in the urine because both can affect progression and treatment decisions.
Stage 1
Kidney function may still look close to normal on routine bloodwork, but other findings suggest kidney disease. These can include persistently abnormal SDMA, dilute urine, abnormal imaging, or protein loss in the urine.
Many dogs at this stage feel normal. The focus is usually on confirming the diagnosis, looking for an underlying cause, monitoring trends, and managing blood pressure or proteinuria if present.
Stage 2
Mild loss of kidney function is present. Some dogs still have few obvious symptoms, while others drink and urinate more than usual.
A veterinary renal diet may be recommended, especially once chronic kidney disease is clearly established. Regular bloodwork, urine testing, blood pressure checks, and weight monitoring become increasingly important.
Stage 3
Kidney function is moderately reduced. Dogs are more likely to develop poor appetite, weight loss, dehydration, nausea, vomiting, anemia, or changes in phosphorus levels.
Treatment is individualized and may include a renal diet, anti-nausea medication, appetite support, phosphorus control, treatment of high blood pressure or proteinuria, and fluids when appropriate.
Stage 4
This is advanced kidney disease. Dogs may have significant nausea, poor appetite, weakness, dehydration, weight loss, anemia, or other complications caused by the buildup of waste products.
The goal is usually to maintain comfort, hydration, nutrition, and quality of life while treating problems that can still be improved.
Why the stage can change
Kidney values can temporarily worsen with dehydration, infection, certain medications, or another illness. That is one reason veterinarians usually look at trends rather than relying on a single lab result.
What matters besides the stage
- Appetite and body weight
- Hydration
- Blood pressure
- Urine protein levels
- Phosphorus levels
- Anemia
- How quickly kidney values are changing
- Other medical conditions
Can kidney disease be cured?
Most chronic kidney disease cannot be reversed. Treatment focuses on slowing progression when possible and controlling complications. Some dogs remain stable for long periods, particularly when disease is identified early.
When to call your veterinarian
Contact your veterinarian if a dog with kidney disease stops eating, vomits repeatedly, becomes unusually weak, seems dehydrated, or suddenly drinks or urinates much more or less than usual.
The bottom line
IRIS stages are useful for organizing treatment, but they do not tell the whole story. Your dog’s symptoms, laboratory trends, blood pressure, urine findings, and response to treatment are just as important as the stage number.
Sources
- International Renal Interest Society (IRIS) CKD staging guidelines
- Merck Veterinary Manual: Chronic kidney disease in small animals
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.