KLH-Based Multimodal Management of Clinically Diagnosed Canine Urothelial Carcinoma: A Two-Case Series

Canine urothelial carcinoma (UC) is commonly managed with NSAIDs alone or in combination with cytotoxic chemotherapy. Clinical evidence for subcutaneous KLH-based immunotherapy in canine UC is lacking. We describe two client-owned dogs with clinically diagnosed lower urinary tract UC managed with NSAIDs, Immucothel®, and selenium supplementation after their owners declined cytotoxic chemotherapy. Case 1 was an 11-year-7-month-old castrated male Maltese with a bladder-neck/proximal-urethral lesion. A presumptive diagnosis was based on a positive veterinary bladder tumor antigen test, cytologic urothelial proliferation with dysplasia, compatible serial imaging, and exclusion of metastatic disease; CADET® BRAF and BRAF-PLUS assays were negative. Piroxicam (0.3 mg/kg PO q24h) was administered from 22 February 2023 through December 2024. The dog received Immucothel® (1 mg SC near the right inguinal lymph node) with intravenous selenium (200 µg/kg diluted 1:1 in saline over approximately 40 min), followed by oral selenium. Serial CT and ultrasonography during follow-up showed persistent localized mural thickening without detectable regional or distant metastasis. Case 2 was an 11-year-old neutered male Poodle with a BRAF V595E-positive urethrovesical-junction lesion managed with firocoxib and the same multimodal protocol. Serial ultrasonographic measurements fluctuated during approximately two years of follow-up, including during changes in NSAID administration and booster interval, without documented metastatic progression. No treatment-associated adverse event required permanent discontinuation in either dog. Because both dogs received concurrent therapies, response assessment was not standardized, histopathologic confirmation was unavailable, and no comparator was included, the contribution of KLH-based immunotherapy cannot be determined. These cases should be interpreted as descriptive clinical observations rather than evidence of efficacy.