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Diagnostic imaging of the urinary tract

image of Diagnostic imaging of the urinary tract
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Abstract

This chapter covers a range of imaging methods for the kidneys, bladder and urethra, including radiography, excretory urography, nephropyelography, ultrasonography, computed tomography, magnetic resonance imaging, nuclear scintigraphy, cystography and urethrography.

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Figures

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7.1 Ventrodorsal images of a normal cat being screened for kidney donation. (a) A survey radiograph shows smoothly marginated, symmetrical kidneys. (b) An image obtained immediately after the administration of intravenous iodinated contrast medium shows the parenchymal blush of the nephrogram phase and early filling of the collecting system indicative of the beginning of the pyelogram phase. (c) An image obtained 10 minutes later shows that the pyelogram phase has not progressed and renal parenchymal opacification has persisted. (d) An image obtained 20 minutes after contrast administration shows a persistent nephrogram, indicative of severe hypotension or contrast-induced renal failure.
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7.2 (a) Sagittal ultrasound image of the left kidney from a healthy 7-year-old neutered female Golden Retriever. The outer cortex (C) is more echogenic than the inner medulla (M). There is a thin hyperechoic line (arrowed) near the corticomedullary junction, representing an incidental medullary rim sign. (b) Sagittal ultrasound image of the left kidney of a healthy 5-year-old West Highland White Terrier allows comparison of the renal cortex (C) with the adjacent spleen (S), confirming that the spleen is more echogenic. (c) The transverse image of the left kidney from the same dog as in (b) shows that the renal papilla (P) is in contact with the hyperechoic fat and fibrous connective tissue in the hilus (arrowed). The spleen (S) is in the near field.
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7.3 The resistive index is being measured from a transplanted kidney in a 4-year-old neutered male German Shorthaired Pointer. The callipers are placed over the arcuate arteries of the kidney and the resistive index is calculated from the Doppler waveform.
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7.4 (a) Ventrodorsal radiograph of a 1-year-old female Siamese cat with renal azotaemia. The kidneys are bilaterally small, measuring less than two lengths of L2. (b) Right lateral radiograph of the same cat as in (a). The caudal margin of the left kidney (arrowed) and the cranial margin of the right kidney (arrowheads) are irregular. (c) Sagittal ultrasound image of the left kidney of a 4-year-old neutered female Yorkshire Terrier with renal dysplasia. The kidney (between callipers) is small and irregular with reduced corticomedullary distinction and increased cortical echogenicity in comparison with the adjacent spleen (S). These findings are suggestive, but not pathognomonic, for renal dysplasia.
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7.5 Sagittal ultrasound image of the left kidney of a 1-year-old neutered male Labrador Retriever with leptospirosis. There is perinephric fluid (F) and the renal cortex (C) is subjectively hyperechoic, which was confirmed by comparison with the spleen (not shown).
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7.6 Ultrasound images of the left kidney of a 3-year-old neutered male German Shepherd Dog with systemic aspergillosis. (a) The sagittal image shows reduced corticomedullary distinction and dilatation of the renal pelvis (between callipers). (b) The transverse image confirms dilatation of the renal pelvis (arrowed) with echogenic fluid and a blunted appearance to the renal papilla (P).
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7.7 (a) Ventrodorsal 10-minute excretory urogram of an 11-year-old neutered female Domestic Shorthaired (DSH) Cat with chronic right-sided nephritis. The right kidney (arrowed) is small with an irregular outer margin. Contrast medium is seen in the small intestine (arrowhead), which is the alternative method of excretion when renal function is compromised. (b) The right lateral radiograph of the same cat as in (a) again shows the irregular and small right kidney (white arrows). Some contrast medium is seen in the urinary bladder and there is a central filling defect (black arrow) consistent with a radiolucent stone or blood clot. (c) Sagittal ultrasound image of the left kidney of an 8-year-old neutered female DSH with chronic kidney disease. There is reduced corticomedullary distinction and the outer margin of the kidney is slightly irregular (arrowed). The kidney is small, measuring 2.2 cm in length.
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7.8 (a) Ventrodorsal 20-minute excretory urogram of a 5-year-old neutered male Pyrenean Mountain Dog with pyelonephritis. The left renal pelvis is mildly dilated and the pelvic diverticuli are blunted (arrowhead). The left ureter is slightly greater in diameter than the right (RU), suggesting ureteritis. UB = urinary bladder. (b) Transverse ultrasound image of the left kidney of a 12-year-old neutered female Beagle with pyelonephritis. The renal pelvis is mildly dilated and the renal papilla is invaginated (arrowed), indicative of necrosis.
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7.9 An 8-year-old neutered female Domestic Shorthaired Cat with renal calculi. (a) The ventrodorsal radiograph confirms that calculi are in the region of the pelves (arrowed) and are not likely to be parenchymal. The left kidney appears rounded, suggestive of hydronephrosis. (b) The right lateral radiograph shows that calculi are superimposed over the kidney shadows in the region of the pelves. Calculi are seen elsewhere in the urinary tract including the ureters (arrowed) and urinary bladder (UB). (c) The sagittal ultrasound image of the left kidney shows severe hydronephrosis with minimal remaining cortex (C). Hyperechoic structures (arrowed) with acoustic shadowing (arrowheads) are seen in the dependent aspect of the pelvis, consistent with calculi.
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7.10 Sagittal ultrasound image of the left kidney of a 6-month-old neutered male Domestic Longhaired Cat with feline infectious peritonitis. The corticomedullary distinction is reduced. The kidney is enlarged, measuring 5 cm in length. There is scant subcapsular fluid/infiltrate (arrowed).
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7.11 Dorsally reconstructed post-contrast computed tomography image of the kidneys of a 2-year-old neutered female Domestic Shorthaired Cat with right renal rupture. Note that contrast has accumulated around the right kidney (arrowed) and very little contrast is located within the right renal pelvis (P) when compared with that of the left kidney (LK). Right renal parenchymal enhancement confirms that the vascular supply has not been compromised.
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7.12 A 14-year-old neutered male Domestic Shorthaired Cat with renal lymphoma. (a) The ventrodorsal radiograph shows that both kidneys (RK and LK) are enlarged, measuring approximately three lengths of L2. Mid-abdominal serosal detail is reduced suggesting ascites, inflammation or lymphadenomegaly. (b) The right lateral radiograph confirms renomegaly, with the left kidney (arrowed) displacing the colon (C) ventrally. (c) The sagittal ultrasound image of the left kidney shows that corticomedullary distinction is reduced. The kidney is enlarged, measuring 5.4 cm in length. There is scant subcapsular fluid/infiltrate (arrowed), which is more echogenic near the poles (between callipers).
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7.13 (a) Ventrodorsal radiograph of an 8-year-old neutered male Beagle with a right renal carcinoma. The caudal margin of the right kidney (arrowed) extends all the way into the caudal abdomen. The left kidney (LK) is displaced laterally and caudally. (b) The right lateral radiograph of the same dog as in (a) confirms right renomegaly (white arrows) with ventral deviation of the faeces-filled colon (black arrows). The left kidney (arrowheads) can be seen summating with the mass. (c) Sagittal ultrasound image of the right kidney of a 15-year-old neutered female Domestic Longhaired Cat with a right renal carcinoma. The cranial pole of the right kidney (RK) appears fairly normal. However, the caudal pole has been replaced by a cavitated mass (arrowed), resulting in distortion of the shape of the kidney. Perinephric fluid (F) is seen and may represent haemorrhage or urine.
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7.14 (a) Ventrodorsal image obtained 20 minutes post-excretory urogram in a 9-year-old neutered female Akita with a solitary left renal cyst. The nephrogram phase of the right kidney (RK) and the cranial pole of the left kidney (LK) appear normal. The caudal pole of the left kidney is enlarged and the parenchyma has been replaced by a non-contrast-enhancing lesion (arrowed) consistent with a cyst. The cyst is displacing the left ureter (arrowheads) medially and the renal pelvis is moderately distorted. (b) Sagittal ultrasound image of the right kidney (between callipers) of a 12-year-old neutered male Persian cat with polycystic kidney disease. There are multiple variably sized cysts throughout the parenchyma, the largest of which (C) shows acoustic enhancement (arrowed), thereby confirming that it contains fluid. The remaining parenchyma is subjectively hyperechoic, and corticomedullary distinction is reduced. The kidney is enlarged, measuring 4.9 cm in length.
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7.15 Sagittal ultrasound image of the right kidney of a 1-year-old female Boxer with a renal abscess. The caudal pole of the right kidney (RK) is normally shaped but displays reduced corticomedullary distinction suggestive of chronic inflammation. There is a fluid-filled mass distorting the cranial pole of the kidney (arrowed). Echogenic debris is seen suspended within the fluid, some of which has settled to the dependent portion of the abscess cavity (arrowhead).
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7.16 A 13-year-old neutered Domestic Shorthaired Cat with bilateral perinephric pseudocysts. (a) The ventrodorsal radiograph shows severe enlargement of the right renal silhouette (RK), which has resulted in displacement of the bowel cranially and medially. The left kidney (LK) is small but appears round and is displaced caudally. Note that the margins of both kidneys remain smooth and well defined. (b) The right lateral radiograph confirms severe right renal enlargement with ventral displacement of the colon (C). (c) The sagittal ultrasound image of the right kidney shows a large accumulation of fluid (F) focally located around the kidney. The kidney has reduced corticomedullary distinction and an irregular outer margin (arrowed) suggestive of chronic kidney disease.
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7.17 (a) Transverse ultrasound image of the right kidney of a 6-year-old neutered male Swiss Mountain Dog with hydronephrosis. The renal pelvis (P) is moderately dilated with anechoic fluid. The renal papilla is blunted (arrowed). The remaining cortex (C) appears normal. (b) Sagittal ultrasound image of the left kidney of an 11-year-old neutered female Domestic Shorthaired Cat with hydronephrosis. There is a large quantity of anechoic fluid in the renal pelvis (P) and very little normal cortex (C) remains. Hyperechoic linear structures extend into the centre of the fluid-filled pelvis (arrowed) and represent the support for the arcuate arteries.
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7.18 Sagittal ultrasound image of the left kidney of an 8-year-old neutered female mixed-breed dog with a known history of ethylene glycol ingestion. The renal cortex (C) is seen to be substantially more echogenic than the adjacent spleen (S). The kidney is enlarged, measuring 8.5 cm in length.
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7.19 (a) Sagittal ultrasound image of the left kidney of a 12-year-old Domestic Shorthaired Cat with a renal infarct secondary to hypertrophic cardiomyopathy. There is a hyperechoic wedge-shaped lesion (arrowed) in the cranial pole of the kidney consistent with fibrosing change of a chronic infarct. (b) Dorsally reformatted post-contrast computed tomography image of the kidney of a 10-year-old neutered female Labrador Retriever with renal infarcts. The outer margin of the kidneys is irregular bilaterally and there are wedge-shaped regions of reduced parenchymal contrast enhancement seen affecting the left kidney (arrowed).
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7.20 Sagittal ultrasound image of the right kidney of a 3-year-old neutered male Shar Pei with amyloidosis. The renal cortex (C) is thick and hyperechoic in comparison with the adjacent liver (L).
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7.21 Sagittal reformatted contrast-enhanced computed tomography image of the caudal abdomen of a 6-month-old neutered female Welsh Corgi with right-sided ectopic ureter. The right ureter (RU) is severely enlarged and the terminal aspect of the ureter (arrowed) bypasses the urinary bladder (UB).
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7.22 Sagittal ultrasound image of the urinary bladder of a 3-month-old female Beagle with a right-sided ureterocele. There is anechoic urine in the urinary bladder (UB) and a mural ureterocele (UC). The wall of the ureterocele is visible (arrowed), separating the two compartments.
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7.23 (a) Right lateral radiograph following a bilateral nephropyelogram in a 1-year-old neutered male Boxer with bilateral hydronephrosis and right-sided hydroureter of unknown cause. The proximal right ureter (arrowed) is moderately enlarged while the distal ureter (curved arrow) is of a more normal diameter. (b) Sagittal ultrasound image of the right ureter of a 10-year-old neutered male Domestic Shorthaired Cat with hydronephrosis secondary to obstructive calculi. Echogenic debris (between callipers) is seen within the lumen of the dilated ureter (arrowed). Obstruction must be present further distally because ureteral dilatation is present caudal to the echogenic debris.
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7.24 An 11-year-old neutered female Domestic Shorthaired Cat with ureteral calculi. (a) The ventrodorsal view shows a large number of calculi in the right ureter (arrowheads) and calculi in the renal pelvis (arrowed). The left kidney (LK) is small and irregular, indicating chronic kidney disease. (b) The right lateral view confirms the presence of calculi in the ureter (arrowheads) and the right renal pelvic region (white arrow). Calculi can also be seen at the ureterovesicular junction (black arrow) and in the urinary bladder (UB).
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7.25 Ventrodorsal view following a right-sided nephropyelogram in an 8-month-old neutered male Domestic Shorthaired Cat with a traumatic ureteral rupture. Contrast medium can be seen in the renal pelvis and proximal ureter (arrowed). Contrast medium can also be seen outside the collecting system (arrowheads) and around the kidney. A peritoneal drain is in place (D).
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7.26 Ventrodorsal view following right-sided nephropyelogram in a 7-year-old neutered male Siamese cat with a ureteral stricture. A needle (arrowed) is seen passing through the abdominal wall and into the renal pelvis. The renal pelvis is dilated and filled with contrast medium. There is blunting of the pelvic diverticuli (arrowhead) consistent with hydronephrosis. The ureter can be seen to terminate abruptly (curved arrow) at the level of L4.
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7.27 Lateral radiograph of a 10-year-old neutered male Labrador Retriever with transitional cell carcinoma of the urethra and prostate. There is an irregular margin along the ventral margin of the ilium and L7, representing polyostotic aggressive bone lesions (arrowheads). The undulating soft tissue structure in the caudodorsal retroperitoneal region (arrowed) is consistent with sublumbar lymphadenopathy. These findings are consistent with metastatic transitional cell carcinoma. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.28 (a) Lateral radiograph of a 5-year-old neutered male Miniature Schnauzer. (b) External compression applied using a wooden spoon when taking a lateral radiograph helps to displace structures of the caudal abdomen, so that the cystoliths (arrowed) are not obscured by overlying bowel loops. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.29 In male dogs, an additional radiographic view with the pelvic limbs pulled forward allows complete evaluation of the penile urethra. (a) Radiograph centred over the caudal abdomen of an 11-year-old male American Staffordshire Terrier. (b) When the pelvic limbs are pulled forward, a stack of uroliths at the base of the os penis (arrowed) are revealed. These were obscured by the femurs in (a). (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.30 (a) A positive-contrast cystourethrogram has been performed in a 12-year-old neutered male Domestic Shorthaired Cat. (b–c) Oblique ventrodorsal views allow the urinary bladder to be moved away from the spine and provide more thorough detail of the mucosal surface. This patient has a broad-based filling defect and irregular surface along the left side of the urinary bladder that was cytologically diagnosed as transitional cell carcinoma by traumatic catheterization. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.31 A pneumocystogram and excretory urogram have been performed to identify the terminal ureters in a 1-year-old neutered female Labrador Retriever with urinary incontinence. The ureters contain contrast medium and have the normal ‘J’ hook shape before entering the urinary bladder. The bladder contains gas from the pneumocystogram and contrast medium from the ureters. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.32 Lateral radiograph of a Domestic Shorthaired Cat following a double-contrast cystogram. The abdominal caudal vena cava is filled with gas and streaks of gas (arrowed) radiating through the liver represent gas within the intrahepatic veins.
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7.33 A retrograde urethrogram was attempted and there has been urethrocavernous reflux of contrast medium into the penile venous drainage and caudal vena cava (black arrows). The patient sustained previous pelvic limb trauma and the limbs cannot be extended, thus they are superimposed on the caudal abdomen. The urinary bladder is severely distended (white arrows).
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7.34 Two lateral radiographs obtained during positive-contrast urethrography in a 7-year-old neutered male Akita with stranguria. (a) This image shows a radiolucent filling defect in the urethral contrast at the level of the ischium (arrowed). (b) A second contrast injection demonstrates that the radiolucent filling defect was transient indicating that it was actually a gas bubble.
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7.35 Transverse ultrasound image from the ventral aspect of a normal os penis in a 14-year-old male terrier cross. The penile urethra runs through the shallow trough along the ventral aspect of the os penis (arrowed). (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.36 Radiographs allow overview of the whole patient. In this single lateral radiograph of a 2-year-old neutered female Yorkshire Terrier there is a large cystolith within the urinary bladder, bilateral renomegaly and severe microhepatia with cranial displacement of the gastric axis. This patient has a congenital portosystemic shunt and has developed an ammonium urate cystolith. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.37 Longitudinal ultrasonographic view of the penile urethra in a 9-year-old neutered male Miniature Poodle. A stack of four urethroliths is present at the base of the os penis (arrowed). (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.38 Longitudinal ultrasonographic image at the trigone of the urinary bladder. The patient is an 8-year-old neutered female Pyrenean Mountain Dog that was presented for stranguria. A distended urinary bladder is present and is confluent with a distended proximal urethra. This is consistent with a distal urethral obstruction. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.39 Longitudinal ultrasonographic image of the urinary bladder in a 12-year-old neutered female American Eskimo Dog with renal haematuria. There is a large blood clot within the lumen of the urinary bladder. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.40 Emphysematous cystitis. Streaks of gas are evident along the margin of the urinary bladder both (a) radiographically and (b) ultrasonographically (arrowed). Ultrasonographically, gas within the wall of the bladder creates a hyperechoic interface with reverberation artefact deep to the surface along both the near and the far wall of the urinary bladder. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.41 (a–b) Longitudinal ultrasound images of a 9-year-old neutered male English Cocker Spaniel. Polypoid cystitis appears as stalks of proliferative mucosa extending into the lumen of the urinary bladder. Polypoid cystitis typically occurs at the apex of the urinary bladder. The cranial aspect of the urinary bladder (the apex) is on the left of the image with the caudal aspect on the right. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.42 Lateral radiograph of a 9-year-old male mixed-breed dog. There are two rounded soft tissue structures in the caudal abdomen. One is the urinary bladder and the other represents a paraprostatic cyst. These structures cannot be differentiated without additional imaging, such as ultrasonography or a cystourethrogram. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.43 A 10-year-old male Golden Retriever with several thin-walled mineralized paraprostatic cysts. One of the paraprostatic cysts extends into the caudal abdomen, dorsal to the urinary bladder (black arrows), while several additional mineralized cysts extend caudally into a perineal hernia (white arrow). Entire male patients are more prone to perineal hernias than neutered dogs. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.44 A magnified view, obtained during a positive-contrast cystogram, showing a small congenital vesicourachal diverticulum (arrowed) filled with iodinated contrast medium at the apex of the urinary bladder in a young male cat. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.45 Longitudinal ultrasound image at the apex of the urinary bladder in a 13-year-old neutered female Shih Tzu. There is a urachal diverticulum that extends from the apex of the urinary bladder towards the ventral body wall. In this example the urachal diverticulum contains both a cystolith and accumulated echogenic debris. The urachal diverticulum opened over time as a large mass developed at the trigone of the urinary bladder and caused partial urethral obstruction. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.46 Traumatic diverticulum in a 9-year-old neutered female Pekingese. (a) Positive-contrast cystography was performed by injecting iodinated contrast medium through a pre-existing cystotomy tube (C). The contrast medium outlines a traumatic diverticulum (arrowed) as a rounded outpouching of the bladder mucosa through a tear in the muscular layer of the bladder. (b) Ultrasound image of the same traumatic diverticulum (arrowed) at the apex of the urinary bladder. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.47 An excretory urogram and cystourethrogram were simultaneously performed in this 2-year-old Bichon Frise following a traumatic event. There is extravasation of contrast medium from a laceration at the junction of the trigone and the proximal urethra. The ureters are normal. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.48 Retrogade positive-contrast cystography confirms a ruptured bladder in this 1-year-old neutered female German Shepherd Dog. The small intestinal loops are spastic and appear corrugated secondary to the uroabdomen. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.49 Lateral radiograph of the caudal abdomen of a 10-year-old neutered female Labrador Retriever that presented for stranguria. The intra-abdominal portion of the urethra is severely thickened (arrowed), creating an abnormal shape at the junction of the bladder and urethra. The patient was cytologically diagnosed with transitional cell carcinoma. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.50 A lateral radiograph of a positive-contrast cystourethrogram in an 8-year-old neutered female Scottish Terrier. There is an undulating mass at the trigone and proximal urethra. The mass has distorted the ureteral papilla and there is ureterovesicular reflux with contrast medium extending into the left ureter and renal pelvis. A measuring device is present within the colon. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.51 Longitudinal ultrasound image of the proximal urethra in a 7-year-old neutered female Rat Terrier. There is a transitional cell carcinoma of the urethra, causing thickening of the urethra with multiple hyperechoic foci representing regions of mineralization (between callipers). (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.52 Transverse ultrasound image of the bladder. Colour Doppler can be used to differentiate mural masses that extend into the lumen and debris or blood clots adherent to the wall of the urinary bladder. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.53 Ultrasound image of a 10-month-old neutered male Scottish Terrier. Botryoid rhabdomyosarcoma is a bladder tumour of young dogs that has the appearance of a cluster of grapes. (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.54 Lateral radiograph of a 4-year-old neutered male Persian cat. There is a traumatic body wall hernia with ventral herniation of the urinary bladder (arrowed). (Courtesy of North Carolina State University College of Veterinary Medicine)
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7.55 (a–b) Sagittal computed tomography images of a retrograde contrast cystourethrogram of a 2-year-old neutered male Miniature Poodle. A very focal circumferential narrowing of the membranous urethra persists on multiple scans of the same region, representing a urethral stricture (arrowed). (Courtesy of North Carolina State University College of Veterinary Medicine)
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