Carotid body carcinoma in a French bulldog treated with toceranib phosphate

Carotid body tumors are rare neuroendocrine neoplasms in dogs, and evidence-based treatment options for malignant or unresectable cases remain poorly defined. An 8-year-old castrated male French bulldog was presented with a large cervical mass accompanied by progressive respiratory distress, neurologic abnormalities, and exophthalmos. Computed tomography revealed multiple, highly vascularized cervical masses with extensive local invasion, including nasopharyngeal obstruction and intracranial extension. Partial surgical excision was undertaken for diagnostic purposes, and histopathologic examination confirmed carotid body carcinoma with intravascular invasion. Because of incomplete surgical resection and malignant features, targeted therapy was initiated. Based on in vitro chemosensitivity testing, toceranib phosphate was selected. Following treatment, clinical signs related to mass effect improved, nasopharyngeal obstruction was alleviated, and increased intratumoral necrosis was suspected on follow-up imaging. Adverse effects were mild and manageable. The dog remained clinically stable for ~5 mo after targeted therapy but was subsequently lost to follow-up. On a later follow-up via telephone, the owner reported that the dog had died 6 mo after initiation of targeted therapy. Key clinical message: This case suggests that toceranib may represent a potential therapeutic option for dogs with unresectable or incompletely resected carotid body carcinoma.