How urine albumin-to-creatinine ratio enhances CKD detection in dogs

Chronic kidney disease (CKD) is a significant health issue in canines, especially as they age. This condition involves long-term, progressive changes in kidney function or structure. CKD can lead to severe complications like anemia, uremic gastroenteritis, and renal secondary hyperparathyroidism.

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Early detection is crucial for managing the disease and improving the quality of life for affected dogs. A key focus in advancing early diagnosis is the use of biomarkers, particularly the urine albumin-to-creatinine ratio (UAC). This ratio has emerged as a valuable tool not only for diagnosing CKD in dogs but also for comparing disease progression between humans and canines.

The measurement UAC is a powerful diagnostic biomarker for CKD, particularly in its early stages. In both dogs and humans, an elevated UAC signals kidney damage. In dogs, veterinarians can use the UAC to differentiate between healthy dogs and those suffering from CKD. The importance of this test lies in its ability to detect CKD early, before other biomarkers like serum creatinine or clinical symptoms show noticeable changes. Research has demonstrated that dogs with CKD exhibit significantly higher UAC values than healthy dogs, making it an essential marker for veterinary diagnostics.

In the Journal of Veterinary Sciences, a study¹ evaluated UAC as a diagnostic tool for early CKD detection in dogs. It included 99 healthy dogs and 122 dogs with CKD, using the International Renal Interest Society (IRIS) guidelines to classify disease stages. The results showed that UAC values were significantly higher in dogs with CKD, particularly in the early stages of the disease, when other markers like serum creatinine might not yet indicate kidney dysfunction. The UAC correlated well with other renal biomarkers such as the urine protein-to-creatinine ratio (UPC), serum creatinine, blood urea nitrogen, and symmetric dimethylarginine,suggesting that UAC can be used alongside these biomarkers to improve diagnostic accuracy.

A critical finding was the introduction of a “grey zone” for UAC values. This zone, defined by a UAC range between 19.20 mg/g and the upper normal limit (64.20 mg/g), represents a diagnostic window where early kidney dysfunction may not be immediately obvious but is still detectable. This concept offers a more nuanced approach to diagnosing CKD, helping veterinarians identify at-risk dogs before they reach more advanced stages of the disease. In this way, grey zone expands the UAC’s diagnostic utility, enabling clinicians to intervene earlier in the disease process and potentially slow its progression.

The study also compared the UAC in dogs to similar biomarkers used in humans. In human medicine, the albumin-to-creatinine ratio is a key biomarker for diagnosing CKD, with microalbuminuria signaling early kidney damage. The UAC cut-off value in humans is typically set at 30 mg/g, which differs from the lower cut-off of 19.20 mg/g found in dogs. This difference highlights the species-specific variations in how kidney damage manifests but reinforces the UAC's role as a useful biomarker for CKD across species. Similar to humans, higher levels of albumin in dogs’ urine correlate with a higher risk of CKD progression. Therefore, monitoring UAC in both humans and dogs can help track the disease over time and guide management strategies.

Despite its promising potential, UAC does have some limitations. Analysis revealed that the UAC has a diagnostic accuracy with an area under the curve of 0.817, which, although promising, is not perfect. The sensitivity and specificity of the UAC at the 19.20 mg/g cut-off value were 72% and 71%, respectively. These results demonstrate that while the UAC is a valuable marker for CKD, it should not be relied upon exclusively. The use of multiple biomarkers in combination provides a more comprehensive and reliable diagnostic approach.

Thus, the UAC is a valuable biomarker for diagnosing early-stage CKD in dogs. It effectively distinguishes between healthy dogs and those with CKD at IRIS stage 1, making it essential in veterinary medicine. When combined with other renal biomarkers, UAC provides a comprehensive approach to diagnosing and managing CKD. As research advances, UAC will likely play an even greater role in early detection, treatment decisions, and improving the quality of life for dogs with CKD.

Ava Landry is a 2026 PharmD candidate at the University of Connecticut in Storrs, where she is studying veterinary pharmacy.

Reference

1. Lee SY, Cha YE, Kang HM, et al. Diagnostic validation of the urine albumin-to-creatinine ratio for early renal disease in healthy dogs and dogs with chronic kidney disease. J Vet Sci. 2024;25(6):e77. doi:10.4142/jvs.24183