Glomerulocystic kidney in a domestic dog

Glomerulocystic kidney was diagnosed in a 5-year-old female Shiba dog, which died from chronic renal failure with convulsions, vomiting and diarrhoea. Haematological examination revealed non-regenerating anaemia, azotaemia and high serum creatinine. Grossly, both kidneys were mildly atrophic with multiple small cysts in the cortex. Histopathological examination revealed marked dilatation of Bowman's space, often with glomerular atrophy or loss, and mild interstitial fibrosis. Bowman's basement membranes (BMs) were tortuous and thickened, with patchy calcification. Glomerulo-tubular junctions in the urinary pole side of the kidneys had a stenotic appearance associated with thickening of Bowman's BMs and calcification. Focal interstitial fibrosis around the glomerulo-tubular junction was also found. Continuity with the proximal tubule was evident in cystic glomeruli. Ultrastructurally, marked thickening of Bowman's BMs with many granular deposits in the urinary pole side was observed. The findings indicate that glomerular cystic changes may have developed as a consequence of glomerulo-tubular junctional stenosis due to thickened Bowman's BMs and focal periglomerular fibrosis in the urinary pole side of the kidneys.     

Micropuncture studies on the dog kidney

Summary Micropuncture studies were carried out on the dog kidney in order to delineate the response of micropuncture parameters to changes in blood pressure within and below the autoregulatory range. By the use of chloralose anaesthesia and carotid sinus denervation elevations in systemic blood pressure were induced, while the use of Regitine permitted the induction of lower BP levels both in the lower part of the autoregulatory range and to frankly hypotensive levels. The results indicate a constancy of intratubular function (TF/P inulin, transit time, single nephron GFR, intratubular pressure) so long as blood pressure remained within the autoregulatory range, supporting the concept of a preglomerular site for autoregulation. During hypotension the single nephron GFR decreased, the transit time was prolonged, but the end proximalTF/P inulin did not change significantly. These changes in tubular function corresponded to a fall in total GFR, RBF, and filtration fraction. The fall in single nephron GFR was greater than the corresponding fall in total GFR suggesting that during hypotension the filtrate of the punctured superficial nephrons is less well protected than that of other nephrons in the dog kidney.Supported in part by a Medical Research Fellowship of the Medical Research Council of Canada.