Abstract
An 11-year-old spayed female Beagle presented with tenesmus and was identified with a rectal wall mass. Diagnostic imaging (abdominal ultrasound and computed tomography) localised the mass in the right rectal wall and documented no evidence of metastatic disease. Subsequently, the dog underwent surgery for tumour excision. A histopathological diagnosis of melanoma was performed. To confirm the tumour histotype, immunohistochemistry was performed using anti-Melan A and anti-Ki67. Neoplastic cells exhibited focal Melan A immunoreactivity and widespread nuclear immunoreactivity for Ki67 with a Ki67 index of 27%. Adjuvant immunotherapy with APAVAC(®) was initiated. After APAVAC administration, no local or systemic acute adverse events were observed. Four pre- and post-contrast computed tomography (CT) studies were performed in an 18-month follow-up period every 4-5 months. Follow-up rectal palpation and conscious visualisation of the surgical site have also resulted in no macroscopic signs of tumour recurrence. The dog remains alive and with no clinical evidence of tumour recurrence and/or distant progression at the time of writing, therefore, surviving over 540 days from the diagnosis.