Exophthalmos associated with frontal sinus osteomyelitis in a puppy

A three-month-old, male Great Dane puppy developed progressive left exophthalmos, epiphora, and swelling of the left frontal bone. Radiographs revealed obliteration of the left frontal sinus by a bone-like density, and lateral sinus wall thickening with extension into the left orbit. On surgical exploration and trephination, the left frontal sinus was filled with soft bone which contained multiple pockets of mucopurulent material. Cytologic examination confirmed the presence of a large number of neutrophils, osteoclasts, and osteoblasts; and both extracellular and intracellular, filamentous, beaded bacteria. The involved bone was debrided, and the defects in the orbital wall and sinus were reconstructed successfully with a temporalis muscle flap.