An 8 year-old male, castrated mixed breed dog presented to the Cornell University Hospital for Animals (CUHA) Emergency service on March 31, 2016, for fever, oral pain and anorexia. Three years prior, he presented to the emergency service for progressive oral pain. A CT was performed and revealed a locally aggressive, mineralized, soft tissue mass of the right ear canal. The mass was surgically cytoreduced via a total ear canal ablation and full bulla osteotomy. A definitive diagnosis of basosquamous cell carcinoma was determined on histopathology of the surgical biopsy.
Basosquamous cell carcinomas are rare. The biological behavior and response to therapy in dogs is not well understood, thus the prognosis is unknown. The owner elected to pursue all available options. The first was a full course of definitive radiation therapy (RT) following the surgery to assist with local control of the tumor. Following RT, chemotherapy was instituted with carboplatin, but was changed to the tyrosine kinase inhibitor toceranib phosphate (Palladia) after repeat imaging showed no change in disease status. Palladia was continued with dose reductions due to its side effects.
On his most recent presentation, the patient was apprehensive and exhibited pain upon palpation of the right side of his face. The remainder of his physical examination was unremarkable. Bloodwork consisting of a CBC and chemistry panel was unremarkable, and urinalysis showed a USG of 1.013 and 2+ protein. A repeat CT examination of his head revealed a progressive, locally extensive, soft tissue mass and bone lysis of the right temporal region. As all known curative therapeutic options had been exhausted, a palliative care regimen was initiated. This included the use of palliative radiation, oral and intravenous analgesics, and the bisphosphonate pamidonrate. This report will focus on the multimodal therapeutic approach used in the palliative care of a mixed breed dog with basosquamous cell carcinoma.