Stages of Kidney Disease in Dogs: Understanding the IRIS Guidelines

If your dog has been diagnosed with kidney disease, you want to know their stage. This article will discuss how veterinarians stage kidney disease in dogs, and how to best understand the International Renal Interest Society (IRIS) guidelines. Knowing what stage of renal disease your dog is in will help with your treatment plans and prognosis.

Understanding kidney disease and failure

Kidney disease can be scary for a lot of dog owners. However, understanding what kidney disease in dogs actually means can go a long way in effective management and treatment. Approximately 25% of all senior dogs over the age of 10 have kidney or renal disease.

In medical terminology, kidney disease and kidney failure are often used interchangeably, although they often represent different clinical signs and symptoms of renal dysfunction.

The kidneys are vital organs responsible for filtering waste from the blood, regulating electrolytes, and many other important functions within the body. When these functions are compromised, it leads to renal issues that can range from mild to severe. Renal disease in dogs and canine kidney issues are other terms you might come across, and they essentially refer to the same condition.

The term acute kidney injury refers to sudden renal failure that requires immediate intervention. This is different from early chronic kidney disease, which is a more gradual onset of kidney dysfunction.

Veterinarians will use diagnostic tests like urinalysis and bloodwork to diagnose kidney disease. Specifically, veterinarians will evaluate creatinine, blood urea nitrogen (BUN), and SDMA (symmetric dimethylarginine) levels to determine the stage of kidney disease in dogs.

The role of IRIS in kidney disease staging

When it comes to managing chronic kidney disease in dogs, a standardized approach is essential for accurate diagnosis and effective treatment. This is where the International Renal Interest Society (IRIS) comes into play. IRIS chronic kidney disease guidelines serve as a cornerstone for veterinarians, offering a structured framework for kidney disease staging and treatment.

The IRIS guidelines are designed to help veterinarians and pet owners alike understand the severity of a dog's kidney disease. These guidelines break down the condition into various stages, providing staging guidelines that include diagnostic criteria and classification systems. Each stage is defined by specific kidney markers, such as creatinine and/or SDMA levels, which are very important for assessing kidney function.

The IRIS staging guidelines: What are they?

IRIS is a worldwide organization that puts out evidence-based guidelines for diagnosing and managing diseases of the kidneys.

These guidelines include a staging system for canine renal disease, which helps veterinarians evaluate how severe the kidney disease is.

The IRIS guidelines separate kidney disease into 4 stages, which are based on the levels of creatinine and SDMA that are found in your dog’s blood testing. The higher the creatinine and SDMA levels are, the more severe the kidney disease is.

Staging is performed after diagnosing chronic kidney disease (CKD) to facilitate proper treatment and monitoring.

Stage 1: Early Detection

• Creatinine: <1.4 mg/dL (<123 µmol/L)
• SDMA: <18 µg/dL

In Stage 1, clinical symptoms are often absent, and standard creatinine levels can even appear normal. Diagnostics may include tests for dilute urine, abnormal kidney palpation, or ultrasound findings.

In this early stage, the focus is often on monitoring and lifestyle adjustments. A balanced diet and regular check-ups are usually recommended to track any changes in kidney function.

Stage 2: Mild Chronic Kidney Disease

• Creatinine: 1.4-2.8 mg/dL (123-247 µmol/L)
• SDMA: 18-35 µg/dL

Dogs in this stage usually do not exhibit noticeable symptoms. If they do, the symptoms are subtle, like reduced appetite or minor weight loss.

Treatment in Stage 2 may include a specialized renal diet and possibly the introduction of medications like ACE inhibitors (benazapril) to manage protein loss (proteinuria) if present. Regular blood and urine checks are important to track the progress.

Stage 3: Moderate Chronic Kidney Disease

• Creatinine: 2.9-5.0 mg/dL (256-441 µmol/L)
• SDMA: 36-54 µg/dL

At this stage, the symptoms can range from mild to severe, including appetite loss, weight loss, vomiting, or lethargy. Monitoring other blood values like phosphorus and potassium levels becomes essential.

In Stage 3, more aggressive treatment is usually required. This could include a strict renal diet, medications to control blood pressure and proteinuria, and perhaps phosphate binders to manage phosphorus levels.

Stage 4: Severe or Late-Stage Kidney Disease

• Creatinine: >5.0 mg/dL (>441 µmol/L)
• SDMA: >54 µg/dL

In Stage 4, clinical signs are usually severe and require immediate medical attention. At this stage, the disease has advanced to a point where quality of life is a major concern.

In this most advanced stage, intensive treatment is required. Along with a strict renal diet, medications for controlling blood pressure, proteinuria, and phosphorus levels are often combined with supportive therapies like fluid administration for diuresis. Unfortunately, the prognosis is very poor for late-stage renal failure.

If you're a dog owner, understanding the IRIS stages can help you navigate through kidney disease diagnosis and treatment. While these guidelines are not meant for the initial diagnosis, they are incredibly useful in creating a personalized treatment plan, monitoring disease progression, and providing insights into the prognosis.

Diagnosing kidney disease

The kidneys are remarkably efficient organs. A dog can lose up to 75% of kidney function before showing any changes in renal blood values such as elevated BUN and creatinine levels.

Therefore, these traditional diagnostic methods could detect kidney failure only after a significant loss of function, making early intervention difficult.

Veterinarians also use the amount of protein in the urine, called proteinuria, as a diagnostic aid. When the kidneys are not functioning optimally due to disease, proteins can leak into the urine, resulting in proteinuria. The detection of proteinuria in dogs is a valuable clinical tool in both diagnosing kidney disease and monitoring its progression.

The emergence of SDMA testing

The Symmetric Dimethylarginine (SDMA) test is a groundbreaking innovation in diagnosing kidney disease in dogs. It is specific to kidney function where the SDMA level increases as kidney function declines with no correlation between total lean mass. Creatinine levels will decrease as muscle mass is lost, making the trending of creatinine difficult.

SDMA detects kidney disease at a much earlier stage, capturing dysfunction when only 30-40% of kidney function is lost.

Therefore, the SDMA levels are much more accurate when it comes to diagnosing kidney disease in its earliest stages.

FAQs

The IRIS guidelines are an essential tool in staging kidney disease in dogs. By understanding the different stages and how they are determined, dog owners can be better equipped to make informed decisions about their pet’s health. Regular monitoring of your dog’s bloodwork and urine is imperative for early detection and intervention, often leading to better management of your dog's condition. Be sure to work closely with your veterinarian to create an appropriate treatment plan that meets the needs of your dog.

If you have any further questions or concerns about the different kidney disease stages and how they apply to your dog, please contact your veterinarian.