Reestablishment of Radiographic Kidney Size in Miniature Schnauzer Dogs

Abstract

Kidney size may be altered in renal diseases, and the detection of alterations in kidney size has diagnostic and prognostic value. It is hypothesized that radiographic kidney size, the kidney length to L2 length ratio, in normal Miniature Schnauzer dogs may be overestimated because of their shorter vertebral length. This study was conducted to evaluate radiographic kidney size, the second lumbar vertebra (L2) length, and ultrasonographic kidney size, the kidney length to aorta diameter ratio, in clinically normal Miniature Schnauzer dogs and other dog breeds, to evaluate the effect of vertebral length on radiographic kidney size, and to reestablish radiographic kidney size in normal Miniature Schnauzer dogs. Abdominal radiographs and ultrasonograms from 49 Miniature Schnauzer dogs and 54 other dog breeds (control group) without clinical evidence of renal disease and lumbar vertebral abnormality were retrospectively evaluated. Radiographic kidney size in the Miniature Schnauzer group (3.31±0.26) was significantly larger than that in the control group (2.94±0.27). Relative L2 length, the L2 length to width ratio, in the Miniature Schnauzer group (1.11±0.06) was significantly shorter than that in the control group (1.21±0.09). However, ultrasonographic kidney sizes were within or very close to normal range both in the Miniature Schnauzer (6.75±0.67) and the control groups (7.16±1.01). Thus, Miniature Schnauzer dogs have breed-specific short vertebrae and consequently a larger radiographic kidney size, which was greater than standard reference in normal adult dogs. Care should be taken when evaluating radiographic kidney size in Miniature Schnauzer dogs to prevent falsely diagnosed renomegaly.