Urine protein-to-creatinine ratio in cattle with subclinical renal disease

Urinalysis is not routinely used in bovine medicine, and there is no evidence as to whether urine protein-to-creatinine ratio (UPC) could be used for the diagnosis of renal diseases in cattle.

The goal of the study was to determine alterations in UPCs observed with different subclinical renal diseases in clinically healthy cattle and to investigate whether UPC can efficiently differentiate cattle with and without subclinical renal pathology.

Kidney and urine samples from 57 clinically healthy adult dairy (44) and beef (13) cattle were collected after slaughter. Urinary protein and creatinine concentrations were measured in an automatic analyzer, and urinary-specific gravity (USG) was measured using a temperature compensated refractometer. Kidney samples underwent histopathologic examination, and the cattle were classified as NL (no renal lesion) and L (lesions detected even in one kidney). Based on USG, the cattle were divided into the Normal USG (≥1.020) and Low USG (<1.020) groups. The cattle with either histopathologic lesions or low specific gravities were considered to have renal disease.

Renal lesions were detected in 37 cattle. UPC values were significantly affected (P < .05) by USG values, and not by the type of lesion detected, breed, or age, and their interactions (P > .05). The analysis revealed that a UPC of ≥0.19 provided an optimal cut-off point for the differentiation between normal animals and those with renal disease with 66.0% sensitivity and 90% specificity.

The UPC calculation is a useful tool for the differentiation of normal cattle and those with renal disease. A UPC of less than 0.19 is associated with the absence of renal damage, whereas higher values raise suspicion for renal disease.