Page 670 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

648 PART IV Specific Malignancies in the Small Animal Patient

and to map and measure iUC masses to subsequently determine risk of recurrence. 1,29 When considering surgery, patient selec-
response to therapy. Cystosonography, cystography, or CT may tion and owner counseling regarding risks (procedural risk, risk
To accurately track response to therapy, regard-
of recurrence) are essential. The risk of tumor seeding at the time
25–28
be employed.
VetBooks.ir less of the imaging approach, it is essential to follow a consistent of surgery is well documented and careful surgical technique is
12,29,30
protocol from visit to visit for imaging modality, bladder disten-
critical.
tion, patient positioning, and images acquired. When using cys- Full-thickness removal of part of the bladder may be consid-
tosonography to monitor response, it is critical to have the same ered in dogs with discrete iUC lesions away from the trigone. In
operator perform examinations over multiple visits. a retrospective study of 37 dogs with iUC treated with partial
cystectomy (all gross tumor removal in 92% of dogs) plus COX
Treatment inhibitors, with or without chemotherapy, the median progres-
sion-free interval (PFI) was 235 days, and the median survival
Localized Therapy time (MST) was 348 days. In a subset of 22 dogs treated with
29
Surgery surgery and daily piroxicam (with or without other systemic ther-
Surgery may be indicated to (1) obtain tissue for a definitive diag- apy), the MST was 722 days. This result is similar to results in a
29
nosis, (2) eradicate lesions amenable to wide excision (e.g., tumors series of nine dogs that had surgical resection of iUC (three dogs
distant from the trigone), and (3) relieve urinary tract obstruc- with tumor-free margins and six dogs with residual microscopic
tion. Local recurrence after partial cystectomy and the presence disease) followed by single-agent deracoxib, in which the MST
of multifocal lesions within the bladder in many dogs with iUC was 749 days. More complex surgical approaches in dogs with
1
support the notion of the field effect or malignant transforma- iUC have also been reported including total cystectomy plus vari-
tion of the entire urothelium in response to carcinogen expo- ous urinary diversion strategies, but serious complications limit
29
sure. Surgical removal of iUC is typically followed by systemic the success of these approaches. 31–34 Prepubic cystostomy catheters
therapy, usually with a cyclooxygenase (COX) inhibitor, to reduce or low-profile cystostomy tubes can be placed to bypass urethral

A B

C D
• Fig. 30.3 Cystosonography images from dogs with bladder masses. Images made in the sagittal (A) and
transverse (B) planes (5 mL/kg fluid distention of the bladder) of an 11-year-old neutered male Shih Tzu
with invasive urothelial carcinoma. To measure bladder masses over multiple time points, it is important
to follow a consistent protocol in regard to level of bladder distention, and patient and probe positioning;
and to have the same operator perform the ultrasonography on each visit. Polypoid cystitis (C, D), which
can appear very similar to iUC, can occur in any part of the bladder including the mid/apex (C) and trigone
(D). The dog imaged in (D) was a 13-year-old spayed female Bichon Frise with history of previous urinary
tract infection, current hematuria, stranguria, atypical epithelial cells in urine, and masses in the mid and
trigone areas of the bladder. Surgical biopsies of the masses confirmed they were polyps. (Courtesy J. F.
Naughton, Purdue University.)