In Part 2 of Mission RENAL, a series on Chronic Kidney Disease (CKD) in pets, Dr. JD Foster, small animal internal medicine and nephrology expert joins to explain how veterinarians interpret blood and urine tests to diagnose kidney disease, what IRIS staging means, and the importance of individualized treatment plans. Sponsored by Royal Canin and Elanco, this guide empowers pet owners with Real Education for Navigating Advanced Longevity in dogs and cats with chronic kidney disease.
What Is Chronic Kidney Disease in Pets?
Chronic kidney disease (CKD) affects how your pet’s kidneys filter waste from the blood. Over time, the kidneys lose function, allowing toxins to build up. The condition is common in older cats and dogs and often develops gradually—so many pets appear perfectly healthy in the early stages.
The earlier veterinarians detect CKD, the more effectively they can manage it and protect your pet’s quality of life.
How Veterinarians Test for Chronic Kidney Disease in Pets
Diagnosing CKD requires both blood and urine testing. These two pieces of information complement each other to show how well your pet’s kidneys are functioning.
Key Blood Tests:
Creatinine: A waste product filtered by the kidneys. High levels mean reduced kidney function.
SDMA (Symmetric Dimethylarginine): Detects kidney dysfunction earlier than creatinine can.
BUN (Blood Urea Nitrogen): Measures another waste product; often used alongside creatinine.
Urinalysis:
Before blood markers rise, urine changes can reveal early kidney disease. Your veterinarian will measure:
Specific gravity (urine concentration)
Protein levels (protein loss in urine can indicate damage)
Signs of infection or crystals
Together, these results tell your vet how well your pet’s kidneys are filtering and concentrating urine.
Understanding IRIS Staging: What the Numbers Mean
Once chronic kidney disease is confirmed, veterinarians use the International Renal Interest Society (IRIS) staging system to categorize disease severity based on lab work numbers. Stages range from Stage 1 (mild) to Stage 4 (advanced).
Dr. Foster reminds pet owners that the staging cutoffs are guidelines, not absolute boundaries.
“A creatinine of 5.1 doesn’t mean your pet suddenly feels worse than at 4.8,” he explains. “We use stages to guide treatment, but every pet is unique.”
How Often Should Kidney Values Be Rechecked?
Kidney disease requires ongoing monitoring. Depending on the stage and stability of your pet’s condition, Dr. Foster recommends:
Every 3–4 months: Routine rechecks (physical exam, bloodwork, urinalysis, blood pressure)
More often: When starting new medications or kidney diets
Every 1–2 months: For pets in advanced stages or with electrolyte changes
Even simple checks like weight, appetite, and hydration help track your pet’s well-being between visits. Talk to your veterinarian about how often they would like to see your pet for a recheck exam or testing.
Red Flags in Blood Work to Discuss with Your Vet
Some lab results may require prompt action:
Electrolyte imbalances (especially potassium): Can cause weakness or affect the heart
Anemia: Common in later stages of CKD; causes fatigue
Rapidly rising creatinine or BUN: Could indicate dehydration or acute worsening
Dr. Foster emphasizes not to panic if you see red numbers on a lab report.
“Talk with your veterinarian. Many mild changes are expected and not cause for alarm.”
Myths About Chronic Kidney Disease in Pets
Myth #1: “Once my pet has kidney disease, there’s nothing we can do.”
Fact: Early detection and individualized care can keep pets comfortable and thriving for years.
Myth #2: “All kidney disease is the same.”
Fact: The underlying cause, stage, and clinical signs differ from pet to pet.
Myth #3: “Online life expectancy charts predict how long my pet will live.”
Fact: Each pet’s response to treatment is unique. As Dr. Foster says,
“I’ve had pets with creatinine over 10 who still ate and felt great!”
The best approach is a strong partnership between pet owners and veterinarians to monitor and adapt treatment as needed.
The Power of Early Detection of Chronic Kidney Disease in Pets
Dr. Foster’s patient Hoppy, an orange cat, was diagnosed only after an acute crisis—but with the right care, he enjoyed many more months of good quality life.
Routine wellness testing (especially in senior pets) helps detect problems like CKD before crisis hits.
Specialists for Chronic Kidney Disease in Cats and Dogs
Many family veterinarians diagnose and manage CKD beautifully. If you need extra support, a veterinary internal medicine or nephrology service can help with:
Complicated staging or rapid changes
High blood pressure, significant protein in urine
Anemia related to CKD in cats
Dialysis or advanced therapies (case-by-case)
Thank You To Our Sponsors:
Sponsor Note
This episode is supported by Royal Canin® and Elanco™️ makers of Varenzin™️-CA1 (molidustat oral suspension). The discussion mentions a conditionally approved FDA treatment to control non-regenerative anemia associated with CKD in cats. Talk with your veterinarian to see what’s appropriate for your pet.
Indication
Varenzin-CA1 is indicated for the control of nonregenerative anemia associated with chronic kidney disease (CKD) in cats.
Important Safety Information
Varenzin-CA1 is for oral use in cats only and prescribed only by licensed veterinarians. Keep this drug and used syringes out of reach of children. Wash hands immediately after use. In case of accidentally swallowing, call a doctor immediately. Women who are or may become pregnant should use the product with caution. Do not give to pregnant, nursing or breeding cats. Before using Varenzin-CA1, talk to your veterinarian if your cat is allergic to molidustat, has a history of seizures or thromboembolic disease predisposition. Use with caution in cats younger than 1 year of age. Common side effects include vomiting and high blood pressure. Red blood cell proportion should be monitored. Click here for complete safety information.
PM-US-25-2257
