Age and Diet Effects on Relative Renal Echogenicity in Geriatric Bitches

Abstract

Under controlled, but varied dietary conditions 35 geriatric, uninephrectomized, spayed Beagle bitches (dogs) observed for 4 years, renal cortical and renal medullary echogenicity was measured relative to hepatic and splenic echogenicity. Regardless of the diet fed, 60-75% of these aged dogs had renal cortical echogenicity less than that of either the liver or spleen across time; 25-35% of these dogs had renal cortical echogenicity equal to that of the liver, but less than that of the spleen across time. Less than 3% of these dogs had renal cortical echogenicity greater than that of the liver, but less than that of the spleen. Only 1 (one) of these dogs had renal cortical echogenicity equal to that of the spleen and that occurred at only one of the 14 chronologic assessments. Therefore, in either mature or aged dogs imaged with 4.0 to 5.0 MHz equipment, the renal cortical echogenicity should be considered normal if it is less than or equal to that of the liver and less than that of the spleen. In 29 dogs imaged with the 4.0/5.0 MHz equipment and 6 dogs imaged with 7.5 MHz equipment, there was no significant diet or individual dog effect. The 7.5 MHz (6 dog) group had significantly higher average cortical echogenicity scores than the 4.0/5.0 MHz (29 dog) group. However, the occurrence of renal cortical echogenicity greater than liver echogenicity was seen in only 5 of 83 samples (approximately 6.0%) made on 6 dogs imaged with 7.5 MHz equipment and only 1 of 375 samples (approximately 0.27%) made on 29 dogs with 4.0/5.0 MHz equipment. With the exception of one occurrence, all dogs had renal medullary echogenicity less than that of the liver or spleen regardless of imaging equipment frequency. The renal medulla was always hypoechoic compared to the cortex.

Ultrasonography of normal , cystic and dysplastic kidney in cattle

“…These results were in agreement with (Braun 1991;1993). Wood (1990) and Churchill (1999) in their studies in dogs found that the renal medulla was always hypoechoic compared to the cortex, uniformly mottled echogenicity of the renal cortex could be clearly differentiated from the less echogenic renal medulla. In this study, the renal cortex was hyperechoic in comparison to the relative hypoechoic renal medullary pyramids in left kidney, however, the cortex and medulla could not be differentiated in right kidney.…”

Renal ultrasonographic abnormalities are associated with low glomerular filtration rate calculated by scintigraphy in dogs

“…The spleen was used as the main organ of comparison in the current study, but it was not always possible to examine the splenic parenchyma at the same depth as the kidney, and this could have affected interpretation of renal echogenicity in some cases. In the recent years, qualitative and quantitative studies on the cortical echogenicity and the effect of artifacts on its intensity have been performed in healthy dogs. Two more recent publications have tried to eliminate patient and technical related biases, avoiding the comparison with other organs and analyzing the mean gray value in ex vivo and in vivo kidneys under standardized experimental conditions.…”

“…Subjective evaluation included the following variables: cortical echogenicity, medullary echogenicity, and kidney shape/contour . The subjective abnormalities detected were graded according to severity using a grading system created for the study, but based on the veterinary kidney ultrasound literature . Kidney severity grades were: grade 0 for normal appearance, grade 1 for mild abnormality, grade 2 for moderate abnormality, and grade 3 for severe abnormality.…”

“…Subjective evaluation included the following variables: cortical echogenicity, medullary echogenicity, 13,16,17,32 and kidney shape/contour. 33 The subjective abnormalities detected were graded according to severity using a grading system created for the study, but based on the veterinary kidney ultrasound literature.…”

“…On account of its wide availability, low cost, and safety, ultrasound is often the first diagnostic imaging method used for investigation of kidney disease. 12 Several studies have analyzed the sonographic features of the kidneys both in normal dogs [13][14][15][16][17][18][19][20][21][22][23] and dogs with kidney disease. [24][25][26][27] It is stated in the literature that morphologically abnormal kidneys may function normally, and that morphological alterations may be absent from functionally impaired kidneys, 3,11 but studies on the association between structural and functional abnormalities are lacking.…”