urinary system imaging in dogs and cats Flashcards
location of kidneys
- retroperitoneal
- more mobile in cats
- ureters not seen
location of right kidney
- more difficult to visualize
- adjacent to & silhouetts with caudate liver lobe
location of left kidney
- more caudal than the right kidney
size of kidney
x-ray
- ratio: renal length to L2 body length (VD projection)
- dog: 2.5-3.5x length of L2
- cat: intact - 2.1-3.2x length of L2; neutered - 1.9-2.6x length of L2
the function of the kidney is evaluated by:
- intravenous urography - x-rays, CT
- +/- nuclear scintigraphy (glomerular filtration rate study)
intravenous urography is based on:
the kidney’s ability to concentrate and excrete the contrast
opacification of kidneys, ureters, bladder
what kinds of mediums are used in IV urography
nonionic or ionic iodinated contrast medium
* IV injection
* excreted by glomerular filtration
* no significant tubular secretion or reabsorption
IV urography gives information about
- kidney morphology and function
- ureter morphology and patency
- bladder morphology
IV urography - procedure
IV contrast bolus; serial radiographs
what are the most common uses for IV urography
- evaluate for ectopic ureters
- ureter patency (rule out obstruction)
- kidney and ureter leakage/rupture (trauma)
what are the contraindications of IV urography
- dehydration
- no absolute contraindications if normal hydration
- relative contraindication: serverely debilitated patients with poor renal function
are normal ureters seen on survey x-rays
no
how to visualize ureters
- ultrasound (may not be visible if normal)
- IV urography
- retrograde vadino-cysto-urethrogram (ectopic ureters in female)
- antegrade pyelography (ultrasound-guided injection of iodinated contrast directly into an abnormally dilated renal pelvis, followed by x-rays)
ureters are not normally visible on survey radiographs unless:
radiopaque ureteroliths are present
normal end on vessels that can be seen:
deep circumplex iliac arteries and veins - common misdiagnosis for ureteral calculi
ureters: exretory urography
- 1-3mm diameter
- retroperitoneal except at the trigone
- caudal “hook” or “J” shape just before the trigone
- segmented due to peristalsis
renal ultrasound is complementary to radiographic studies:
- size
- shape
- interal architecture
- vasculature
renal ultrasound is what dependent
2 things
operator and equipment dependent
renal ultrasound size
- dogs: renal length to aortic diameter: 5.5 -9.1
- cats: 3.8 - 4.4 cm
renal ultrasound echostructuture
medulla < cortex </= liver < pelvis/sinus
in dogs and cats the medullary rim sign is:
incidental
in cats a thick medullary band sign:
may be associated with kidney disease
in cats a hyperechoic cortex can be :
normal - lipid vaculoles in cortex
in dogs and cats, minimal pelvic dilation is:
normal
urethra - survey x-rays
- not usually seen in dogs
- can see long bladder neck and proximal urethra in cats
what are indications to do a retrograde cystography/cysto-urethrography
- assess bladder integrity, size, shape, position
- lower urinary tract clinical signs
- abnormal urinalysis
- persisten, recurring or chronic UTIs
positive contrast - cystography
- procedure of choice for bladder location and integrity
- iodinated contrast
negative contrast - cystography
- least sensitive
- air or CO2
double contrast - cystography
- contrast procedure of choice for bladder wall or intraluminal abnormalities
- ultrasound used more routinely
urethrography - positive contrast
- similar principles as cystography
- male dogs: prostatic urethra mildly narrower
- retrograde vagino-cysto-urethrogram: contrast refluxes into urethra
ultrasound of bladder
- urine should be anechoic
- bladder wall generally < 2-3mm thick, 3 layered pattern
is the prostate normally seen in cats or neutered dogs
no - only in intact male dogs
what is the fat triangle
prostate x-ray
- body wall (ventral)
- bladder (caudoventral margin)
- prostate (cranioventral)
size of prostate in intact male dogs on x-ray
- lateral: length or height as % of pubic brim to sacral promontory dimension (normal <70%)
- VD: < 50% of the pelvic inlet width
prostate - dogs - ultrasound - difference between intact and neurtered
- intact: hyperechoic
- neutered: small, relatively hypoechoic
