N-acetyl-beta-D-glucosaminidase activity in urine of cows with renal parenchymal lesions

Objective-To measure N-acetyl-beta-D-glucosaminidase (NAG) activity in urin e of cows with renal diseases and to correlate values for NAG activity with renal lesions. Animals-8 lactating Holstein cows and a Japanese Shorthorn cow, all of whic h had renal disease. Procedure-Urine samples were collected, and urinary NAG activity and creati nine concentration were measured. The NAG activity was expressed as units p er gram of creatinine (NAG index). Cows were euthanatized, necropsy was per formed, and correlations between results for urinary NAG index and histopat hologic findings for the kidneys were evaluated. Results-The NAG activity and NAG index in urine samples obtained from cows with interstitial nephritis were high, ranging from 4.2 to 13.6 U/L and 3.5 to 23.0 U/g, respectively. A cow with renal amyloidosis also had high valu es for urinary NAG activity and NAG index. Histologic examination of the ki dneys revealed various kinds of parenchymal lesions. However, urinary NAG i ndex in cows with enzootic bovine leukosis was low. Conclusions and Clinical Relevance-Cows with renal diseases had high urinar y NAG indexes that correlated well with their renal lesions, except for cow s with enzootic bovine leukosis. Therefore, measurement of NAG index in uri ne samples has the potential to provide new perspectives on clinical diagno sis of renal disease in cattle.