7 Key Points on Dog Kidney Markers — BUN, Creatinine, and SDMA — According to Veterinarians

KidneyTop PicksMeongsiljang Veterinary Advisory Board

To accurately assess your dog’s kidney function, blood tests that include BUN, creatinine, and SDMA are essential. These tests allow for the early detection and management of kidney disease.

What Is a Dog Kidney Function Blood Test (BUN, Cr, SDMA)?

A veterinarian drawing blood from a puppy.

A kidney function blood test for dogs measures BUN, creatinine (Cr), and SDMA levels to assess whether the kidneys are functioning normally. These three indicators reflect the kidneys' ability to eliminate waste products. In particular, SDMA can detect early kidney damage, providing more sensitive information than traditional tests. Since kidney disease in dogs often shows no symptoms in its early stages, regular testing is essential.

Selection Criteria: Tips for Choosing a Clinic for Kidney Blood Tests

When selecting a blood test for your dog’s kidney function, there are four key factors to check. First, make sure the test includes SDMA. Tests that only measure BUN and creatinine may miss early kidney damage. Second, check how long the test takes. To quickly detect changes in kidney function, results should be available within 24 hours. Third, compare the cost of the test. Since regular testing is repeated, consider the long-term expenses. Fourth, verify whether the testing facility is recommended by your veterinarian. Professional labs provide higher accuracy.

A veterinarian reviewing a puppy’s blood test results.

Check 1: Whether a Kidney Panel Including SDMA Is Available

While blood tests for kidney function typically include BUN and creatinine, these markers often don’t rise until kidney function has significantly declined. SDMA, on the other hand, reflects decreased kidney function at an earlier stage, so it’s beneficial to choose a clinic that offers a kidney panel including SDMA. This is especially important for senior dogs or breeds prone to chronic kidney disease, as early detection is key. Be sure to confirm which markers are included in the test before your pet’s checkup.

Premium supplement bottle for dogs with kidney issues

Check 2: Whether Hydration Status and Urinalysis Are Considered Together

Blood test results can vary depending on hydration status and whether the patient is fasting, so it’s important to interpret them in the context of the animal’s hydration level at the time of testing. Additionally, kidney function should be assessed not only through blood tests but also alongside urine tests such as urine specific gravity and urine protein-to-creatinine ratio (UPC) for accurate evaluation. Choosing a clinic that offers both renal blood and urine testing, and can also perform blood pressure measurements when needed, allows for a more comprehensive assessment of kidney health.

Affordable Kidney Support Supplement for Dogs

Check 3: Whether Results Are Interpreted and Tracked According to IRIS Staging Guidelines

With kidney disease, tracking how values change over time is more important than looking at a single set of results. It’s best to choose a clinic where the veterinarian classifies your pet’s current condition according to international IRIS staging guidelines, compares it with previous test results to explain the rate of progression, and provides guidance on dietary, fluid, and medication management tailored to those values while also scheduling the next follow-up tests. With such comprehensive care, chronic kidney disease can be managed stably.

Natural ingredient kidney support supplement for dogs

Checklist for Choosing a Clinic for Kidney Function Blood Tests

Item	Recommended Criteria
Test Items	A facility that reviews a renal panel including SDMA in addition to BUN and creatinine
Test Operation	A facility that considers hydration status and also reviews urinalysis such as urine specific gravity and proteinuria
Interpretation Capability	A veterinarian who classifies and interprets kidney status based on IRIS staging criteria
Result Interpretation	A facility that compares with previous values to explain the rate of progression and management direction
Cost Guidance	A facility that informs you in advance of estimated costs and the possibility of additional tests before the procedure

This is not a table recommending specific products or hospitals, but a reference for when you consult your veterinarian. Decisions about treatment and testing must always be made together with your veterinarian through an examination.

Caution: Always Consult Your Veterinarian When Interpreting Test Results

BUN and creatinine levels can vary depending on a dog’s age, muscle mass, hydration status, and diet—particularly high-protein diets—so they shouldn’t be interpreted in isolation. In contrast, SDMA is largely unaffected by age, body size, or muscle mass, making it a relatively stable indicator. However, elevated SDMA may not only indicate intrinsic kidney disease but also result from dehydration (prerenal causes), urinary tract obstruction (postrenal causes), or other underlying conditions. Therefore, diagnosis should never rely on a single value; instead, a veterinarian must comprehensively assess the dog’s overall health, including hydration status and urinalysis, before reaching a conclusion.

Usage Tip: Maintain Kidney Health with Regular Testing

To maintain your dog’s kidney health, regular blood tests are essential. Senior dogs or those at risk of chronic kidney disease should be tested more frequently, following the schedule recommended by your veterinarian. For example, if your dog is on medication such as blood pressure drugs, kidney markers (BUN, creatinine, and SDMA) and proteinuria are typically checked every 3 to 4 months. While fasting before the test can improve accuracy, ensure your dog continues to drink water as usual to stay well-hydrated. Dehydration can cause kidney values to appear higher than they actually are, leading to misinterpretation of the results. Always follow your veterinarian’s recommendations for dietary adjustments and hydration based on the test results. - Regular Testing: Rather than adhering to a fixed schedule, follow the testing frequency advised by your veterinarian. If your dog is undergoing medication therapy, checks are usually performed every 3 to 4 months. - Fasting: Withhold food before the test, but allow your dog to drink water normally to maintain hydration. - Hydration: After the test, ensure your dog has constant access to fresh water as directed by your veterinarian. - Dietary Management: If your dog has chronic kidney disease, switching to a prescription renal diet can help extend lifespan and improve quality of life.

A puppy drinking water and eating canned food.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A 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

When is the best time to have a dog’s kidney function blood test?

While textbooks don't define an absolute schedule, it's recommended that senior dogs or those at risk for kidney disease have regular check-ups, and more frequent ones as determined by your veterinarian. If your dog is on medication such as blood pressure drugs, kidney values and protein in the urine are typically checked every 3 to 4 months. If your dog's health is unstable or they have underlying conditions, your vet may recommend more frequent testing.

Why is the SDMA test important?

SDMA levels begin to rise when kidney function declines by about 40%, whereas creatinine levels only increase noticeably after approximately 75% of kidney function is lost. As a result, SDMA reflects kidney dysfunction earlier than creatinine and is minimally affected by age or muscle mass, making it a more sensitive marker for early detection.

Should my pet avoid eating or drinking before the test?

For accurate results, it’s best to fast before the test, but you should still let your pet drink water as usual to stay well-hydrated. Dehydration can cause kidney values to appear higher than they actually are, leading to misinterpretation. However, if your pet is not in good health, adjustments can be made after consulting with your veterinarian.

What should I do if the results come back abnormal?

Be sure to follow your veterinarian’s recommendations for additional testing, dietary management, and medication. Early intervention is crucial in kidney disease, as it significantly impacts both life expectancy and quality of life.

My dog is afraid of medical exams. What should I do?

Our veterinarians provide compassionate care and help ensure your dog feels comfortable during examinations. Some clinics even offer a calming space for your pet before the check-up begins.

Top 5 Cat Kidney Supplements Recommended for 2026

Top Recommended Prescription Renal Diets for Cats and Key Selection Criteria

Top 5 Prescription Diets for Cats with Chronic Kidney Disease — Stage-Specific Protein Adjustment

Top 7 Prescription Diets for Feline Bladder and Urinary Tract Health Recommended by Veterinarians — Including Selection Criteria

Best Low-Allergen Single-Protein Cat Foods and Selection Criteria: A Complete Guide

Top 5 Moisturizing Skincare Products for Dogs with Dry Skin — Complete Guide to Choosing the Right One

Top 5 Joint-Support Mats and Stairs for Dogs and How to Choose Them

Best Cat Eye Health Supplements for Tear Stains and Dry Eyes: Recommendations and Selection Criteria

Best Low-Irritant Cat Food for Enteritis: Recommendations and Selection Criteria

Best Low-Fat Dog Food Recommendations for Pancreatitis and Selection Criteria

References

[1] The Cat, Clinical Medicine and Management, 2nd Edition, 2023

[2] Small Animal Critical Care Medicine, 3rd Ed, 2022

[3] The Veterinary Workbook of Small Animal Clinical Cases, 2021