Contrast cystography or abdominal ultrasonography
Bladder masses can be detected by contrast cystography or abdominal ultrasonography. Ultrasonography is more commonly used
because it provides better visualization of the mass when proper equipment is used by an experienced ultrasonographer. To
enhance visualization and localization of any masses (Figure 1), make sure the bladder is well-distended with urine or infused with saline solution.
Figure 1. An ultrasonogram of a mass in the trigonal area and a distended ureter resulting from partial ureteral obstruction
in a 9-year-old male castrated Shetland sheepdog with transitional cell carcinoma.
Another advantage of ultrasonography is improved visualization of other abdominal structures. This includes better evaluation
of the kidneys and ureters for possible complications and the assessment of potential metastatic sites, including the lymph
nodes, liver, and spleen.
Additionally, ultrasound guidance can help you select an appropriate biopsy site for transurethral traumatic catheterization,
improving the diagnostic yield. While this diagnostic procedure has a relatively high yield for biopsy samples, the samples
are usually small, occasionally making histologic interpretation difficult.21 Samples obtained with transurethral traumatic catheterization can also be submitted for cytologic analysis and are often
highly cellular and of good diagnostic quality when quickly processed and fixed on glass slides, leading to a presumptive
diagnosis (Figure 2). Nevertheless, histologic examination of tissue biopsy samples remains the only definitive method of confirming urinary
bladder transitional cell carcinoma.
Figure 2. A photomicrograph of a cytocentrifuged urine sample obtained by traumatic catheterization in a 10-year-old male
castrated Scottish terrier showing sheets and clusters of round to polygonal cells with a moderate amount of basophilic cytoplasm.
The nuclei are round with a stippled chromatin pattern and prominent, multiple nucleoli. Note the moderate anisocytosis and
anisokaryosis (Wright's stain, 400X). (Photo courtesy of Dr. Anne Barger, DACVP.)
Once a diagnosis of transitional cell carcinoma has been confirmed, the patient should be clinically staged. Like most solid
tumors, transitional cell carcinoma can metastasize to numerous sites, and suspect findings should be evaluated to obtain
prognostic information before you pursue therapy (Table 1).3
Appropriate imaging includes three-view thoracic radiography and abdominal ultrasonography to evaluate for distant or regional
metastatic disease, respectively. Reported metastatic rates in dogs with histologically confirmed transitional cell carcinoma
are 20% to 37%, with regional (iliac) lymph nodes and lungs being the most common sites.1,3
Table 1 TNM Staging of Canine Bladder Transitional Cell Carcinoma*