Chronic kidney disease is one of the most common health conditions in aging cats, affecting an estimated 30 to 50% of cats over the age of 10. Because the disease develops gradually, many owners don’t realize something is wrong until it has progressed significantly.

Dr. Autumn Harris, a board-certified veterinary internist and associate professor at the NC State College of Veterinary Medicine, is working to change that. Her research focuses on improving how veterinarians detect, monitor and treat kidney disease — and she’s currently leading the CATNIP study, which is evaluating whether newer technologies can better track CKD progression. The study is actively recruiting cats, and participation is free.

We asked Dr. Harris to share what cat owners should know — from early warning signs to the latest advances in diagnosis and at-home care.

Q: What is chronic kidney disease (CKD) in cats, and how common is it as cats get older?

Harris: CKD means the kidneys have gradually lost some of their function. Because kidneys help remove waste products, balance water and electrolytes, and help regulate blood pressure, a slow decline can eventually lead to increased thirst and urination and other signs of illness. CKD is very common in older cats; estimates vary by study, but roughly 30 to 50% of cats over 10 years may be affected, and the percentage rises in very senior cats.

Q: What early signs should owners watch for that might suggest their cat is developing kidney disease?

Harris: Early CKD can be subtle. Common early clues include:

• Drinking more and peeing more (larger clumps in the litter box)
• Weight loss or loss of muscle (even if appetite seems “OK” at first)
• Decreased or pickier appetite
• Vomiting or nausea and licking lips
• Lower energy or hiding more
• Dehydration (dry gums, not grooming as well)
• Bad breath (sometimes “chemical” or uremic odor)

Because these signs can overlap with other conditions, vets also pay attention to early red flags such as persistently low urine concentration and high blood pressure.

Q: How has the diagnosis and monitoring of CKD in cats improved in recent years? Are there newer tests owners should know about?

Harris: Monitoring has improved in a few ways:

• Better, more complete monitoring, not just kidney numbers: Modern CKD care routinely includes urine protein testing (UPC), and phosphorus, potassium, serum bicarbonate, and blood pressure measurements because these strongly influence comfort and long-term outcomes.
• Earlier blood markers: In addition to creatinine, many vets use symmetric dimethylarginine, (SDMA), which can help detect reduced kidney filtration earlier in some cats and is less affected than creatinine by muscle loss. Traditionally, most kidney tests measure how well the kidneys filter, but they don’t always tell us whether there is ongoing active injury to kidney tissue. Newer biomarkers are being studied that may help identify this earlier phase of damage. One promising marker is cystatin B, which is being investigated as an indicator of active kidney injury and tubular cell stress. While creatinine and SDMA reflect renal filtration function, injury biomarkers such as cystatin B may help us determine whether kidney tissue itself is undergoing active damage. This distinction is important because identifying active injury earlier could allow more timely intervention and potentially slow progression. Many of these markers are still primarily in the research phase, but they represent an exciting step toward more individualized and earlier CKD care.

Q: What are the most important things owners can do at home to help a cat living with CKD maintain a good quality of life?

Harris: The highest-yield home steps are practical and very doable:

1. Get regular rechecks. Periodic blood work, urine testing and blood pressure checks help catch treatable issues early (dehydration, anemia, electrolyte imbalances, protein in the urine, hypertension).
2. Prioritize nutrition. A kidney (“renal”) diet (especially phosphorus-restricted) is one of the most impactful interventions for many, with fewer uremic episodes and longer survival. If a cat won’t eat it, the priority is still calories in; your vet can help with gradual transitions, texture/flavor options, toppers or alternatives.
3. Support hydration. Encourage water intake (water fountains, multiple bowls, adding water to food and more canned food). 
4. Track trends at home. Monitor appetite, body weight, litter box volume, vomiting and overall behavior; small changes over weeks matter more than in a single day.
5. Give prescribed meds consistently. Common quality-of-life and kidney-supportive therapies may include anti-nausea meds, appetite support, potassium supplementation, alkalinizing therapy, phosphate binders (when indicated) and blood pressure medication if hypertensive.

Q: You currently have a study recruiting cats with CKD. What is the study’s goal, and how might participation help cats now and in the future?

Harris: This study is designed to evaluate whether newer technologies can better detect and track CKD progression, specifically shear wave elastography (to estimate kidney fibrosis/stiffness) and transdermal glomerular filtration rate, (GFR), to estimate kidney filtration through the skin, and then to correlate those results with standard clinical pathology (blood and urine results). 

The study is enrolling cats in four groups, those without CKD and those with CKD in stages 2a, 2b or 3, with a goal of 10 cats per group. Enrolled cats will visit the clinic five times over two years for a set of tests that include a physical exam and blood pressure check, blood and urine collection, and two types of kidney filtration measurement (one using an injected contrast agent called iohexol, the other measured non-invasively through the skin). Each visit also includes an ultrasound technique called shear wave elastography, which estimates kidney stiffness as a way to assess scarring and fibrosis.

What participation looks like (high level):

• Cats are enrolled as non-CKD, stage 2 (2a/2b) or stage 3, with a goal of 10 cats per group and are followed over five visits (Day 0, 180, 360, 540, 720).
• Visits include a physical exam and blood pressure measurement, blood/urine collection, GFR measured by two methods (iohexol and transdermal) and ultrasound with shear wave elastography. 

Benefits of Participation 

• Zero cost for enrolling your cat in this study 
• Complimentary physical exams for your cat at each visit 
• Free diagnostic testing (bloodwork and urinalysis)
• Specialized recommendations for managing your cat’s CKD from a feline CKD specialist
• Contribution to novel research that will benefit all cats with CKD. 

The goal is simpler and more personal care for every cat with kidney disease. If these tools prove reliable, veterinarians could detect CKD earlier and track its progression more precisely — moving away from broad staging categories and toward treatment plans tailored to the individual cat.

The transdermal GFR measurement is particularly promising. Because it’s non-invasive, it could make routine kidney monitoring easier and less stressful for cats and owners alike. More frequent, more comfortable monitoring means catching changes sooner and acting on them faster — which, for a disease that progresses quietly over months and years, could make a meaningful difference in how long and how well a cat lives.

If your cat has been diagnosed with CKD or is 10 or older and you’d like to learn more about enrolling, visit the CATNIP study page or contact the Harris Lab at [email protected].