Changes in Renal Resistive Index Values in Healthy Puppies during the First Months of Life

Abstract

The purpose of this study is to establish renal resistive index (RRI) of normal kidneys in puppies aged from newborn to 20 weeks of age and to determine the age at which RRI reaches adult dog values. Six healthy adult intact beagles and six puppies from 1 day after birth to 20 weeks of age were used. In the adult dogs, the ultrasonographic scans were performed once, and in the puppies, the ultrasonographic studies were performed on the first day after birth and at 1, 2, 3, 4, 6, 8, 12, 16, and 20 weeks of age. RRI was obtained at the interlobular and arcuate arteries in each kidney. There were no statistical differences between the RRI values obtained between the right and left kidney nor between intrarenal arteries (interlobar and arcuate). The RRI was the highest during the first weeks of life, after which it declined gradually with increasing age reaching adult dog values at 12 weeks of age. In conclusion, the normal mean RRI is age dependent in dogs. Twelve weeks can be regarded as the age at which adult mean RRI criteria can be applied to puppies.

Transabdominal Renal Doppler Ultrasound in Healthy Adult Holstein-Friesian Cows: A Pilot Study

“…It has previously been established that these indices are typically constant in adults, both in humans [ 11 , 18 , 19 ] and animals [ 20 , 24 ], as in the present study. Nevertheless, the values are different from those in new-born and childhood [ 9 , 17 , 20 ]. Siwinska et al [ 33 ] also found that RI values were higher in elderly horses (>18 years) than in foals and adults, but were always below the upper value of 0.70.…”

“…Doppler US of the kidneys provides dynamic information about the renal blood flow associated with renal function [ 10 ] and about how this is modified by different physiological factors and/or pathological conditions [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. It can be used as a guide for renal biopsies to reduce haemorrhage risk [ 7 , 21 , 22 ], by providing information about microvascular and parenchymal lesions [ 10 ].…”

“…Age, sex and body weight (BW) have been studied as potential factors influencing the RI in humans [ 11 , 19 ], dogs [ 20 ], cats [ 9 , 23 ], horses and donkeys [ 24 , 25 ]. Although sex has not been identified as an influential factor in any species, age [ 11 , 20 ] and BW can alter the RI [ 23 ].…”

“…Age, sex and body weight (BW) have been studied as potential factors influencing the RI in humans [ 11 , 19 ], dogs [ 20 ], cats [ 9 , 23 ], horses and donkeys [ 24 , 25 ]. Although sex has not been identified as an influential factor in any species, age [ 11 , 20 ] and BW can alter the RI [ 23 ]. Differences between right and left kidney RI have also been investigated in humans, dogs, horses, and cats, and although contradictory results have been reported [ 9 , 11 , 12 , 20 , 24 ], some difference can be observed in hypertensive patients or can be considered indicative of urinary obstruction [ 20 ] or a result of anatomical and physiological differences between the right and left kidney [ 25 ].…”

“…Although sex has not been identified as an influential factor in any species, age [ 11 , 20 ] and BW can alter the RI [ 23 ]. Differences between right and left kidney RI have also been investigated in humans, dogs, horses, and cats, and although contradictory results have been reported [ 9 , 11 , 12 , 20 , 24 ], some difference can be observed in hypertensive patients or can be considered indicative of urinary obstruction [ 20 ] or a result of anatomical and physiological differences between the right and left kidney [ 25 ]. Other influencing factors such as breed and the effect of training have also been investigated in cats [ 26 ] and horses [ 24 ].…”