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NOVEMBER/DECEMBER 2017
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TVPJOURNAL.COM
Ultrasonography of the Urinary
Tract: Kidneys and Ureters
Elizabeth Huynh, DVM, and Clifford R. Berry, DVM, DACVR
University of Florida
IMAGING ESSENTIALS
NORMAL ULTRASONOGRAPHIC
FEATURES
Kidneys
The kidneys are paired structures located in the
retroperitoneal space and surrounded by adipose tissue.
Normal kidneys are symmetric in size and shape; they
can be oval shaped in cats and bean shaped in dogs.
The cranial pole of the left kidney is adjacent to the
greater curvature of the stomach and dorsomedial to
the craniodorsal extremity of the spleen (seen cranial
and lateral). In dogs, the right kidney is located
more cranially than the left kidney and lies within
the renal fossa of the caudate lobe of the liver. In
cats, the right kidney is often separated from the
caudate lobe of the liver by retroperitoneal fat.
The widely accepted normal ultrasonographic
measurement for kidneys in a cat varies between 3
and 4.3 cm in length. One report proposed that feline
kidneys can measure 3.2 to 4.1 cm in length, 2.2
to 2.8 cm in width, and 1.9 to 2.5 cm in height.
1
Currently, there is no widely accepted method
for determining ultrasonographically normal
kidney size for dogs. Ultrasonographic size is
usually subjective. The following are proposed
methods of measuring normal canine kidney size
that have been discussed in recent reports:
• The ratio of the left and right kidney to the length
of L5 or L6, with normal being 1.3 to 2.7
2
• The ratio of kidney length to aortic diameter,
with normal ranging from 5.5 to 9.1
3
When viewing the kidneys in sagittal orientation, the
renal sinus, medulla, and cortex can be identified.
The renal medulla is the least echogenic region,
followed by the renal cortex, and then the renal sinus
with hyperechoic fat ( Figure 1 ).
4
When assessing for
changes of the renal parenchyma, the corticomedullary
Welcome to our series of articles on small animal
abdominal ultrasonography. The initial articles
provided an overview of basic ultrasonography
principles and a discussion about how to perform
a systematic scan of the abdomen. The rest of the
series discusses ultrasound evaluation of specific
abdominal organs/systems.
Read the other small animal abdominal
ultrasonography articles published in Today's
Veterinary Practice at tvpjournal.com .
IMAGING
ESSENTIALS