A simple urine test may soon help veterinarians identify which dogs with chronic kidney disease are at highest risk of rapid decline. Researchers at North Carolina State University have discovered that measuring ammonia-to-creatinine ratios in urine—a marker long studied in human medicine—could serve as an early warning signal for dogs facing the most serious outcomes from their condition.
The finding matters because chronic kidney disease is one of the most common health challenges in aging dogs, and knowing which animals are progressing fastest could allow vets to intervene sooner with targeted therapies. Autumn Harris, an associate professor of nephrology-urology at NC State, led the research alongside collaborators from the University of Florida. "In people, there's a clear link between reduced ammonia excretion over a 24-hour period and accelerated kidney disease," Harris explains. "However, as there isn't a lot of information about this relationship in dogs with chronic kidney disease, we designed this study to see if UACR levels might be associated with disease progression and outcomes."
The team enrolled 50 dogs—22 female and 28 male—who were already being treated for stage 2-4 chronic kidney disease and managed with a therapeutic kidney diet. Over 12 months, the dogs underwent blood and urine sampling five times total, with researchers tracking their biochemical markers and health outcomes. The results were striking: dogs with a urine ammonia-to-creatinine ratio below 2.0 at the start of the study were three times as likely to die from kidney failure, experienced faster disease progression, and had shorter overall survival times compared to dogs with higher ratios.
What makes this discovery particularly valuable is its timing. The researchers found that abnormal ammonia excretion in urine appears to be an earlier indicator of acid dysregulation than traditional blood tests commonly used to monitor kidney disease progression. Most of the dogs in the study had normal serum bicarbonate concentrations—what vets typically check—yet showed clear abnormalities in their urine ammonia levels. This means UACR could catch problems before they show up on standard bloodwork, giving veterinarians a head start in treatment.
The mechanism mirrors what happens in humans with kidney disease. When kidneys struggle to function properly, they lose their ability to excrete acids like ammonia through urine. This leads to metabolic acidosis, a dangerous buildup of acid in the body that can accelerate disease progression and worsen outcomes. By measuring how much ammonia a dog's kidneys are still able to clear, vets gain insight into how well that crucial acid-regulation system is holding up.
Harris sees immediate clinical potential: "These findings indicate that UACR might serve as a clinically useful and non-invasive biomarker to identify dogs at risk of progression of their kidney disease who might benefit from early, targeted alkaline therapeutic intervention. Additionally, UACR could be used to help determine the prognosis for dogs with chronic kidney disease, allowing for interventions that could improve quality of life in these animals."
The research, published in the Journal of Veterinary Internal Medicine, involved additional collaborators including Rebeca Castro and Shelly Vaden from NC State, and Alexis Copper, Andrew Specht, and Kirsten Cooke from the University of Florida. For dog owners facing a chronic kidney disease diagnosis in their pet, this simple urine test represents a concrete way to understand disease trajectory and pursue treatments tailored to their individual dog's needs.