Case Report of a Rare Clinical Presentation of Craniomaxillofacial Osteosarcoma in an Adult Male Dog.

An 8-year-old intact male German Shorthaired Pointer presented as a referral for a one-week history of unilateral ocular discharge of the left eye and progressive temporalis muscle atrophy. Severe temporalis muscle wasting was appreciated, with periorbital asymmetry. Computed tomography showed aggressive and extensive multifocal bone lysis, primarily on the left rostral aspect of the skull, affecting the cribriform plate, frontal bone, ethmoid bone, zygomatic bone, and maxilla, with marked left temporal muscle atrophy and near-complete collapse and destruction of the left frontal sinus. Bone biopsy revealed osteoblastic osteosarcoma of the skull. Aside from the physical examination abnormalities, the patient did not exhibit pain, lethargy or anorexia at home or while in hospital. This case is notable for the unusual presentation, clinical manifestation and location of osteoblastic osteosarcoma in dogs. The survival time of 132 days was calculated starting from the date of confirmed histopathologic diagnosis, or 159 days from the date of the computed tomography scan.