Zygomatic Sialadenitis as a Rare Cause of Exophthalmos in a Dog

To describe the clinical presentation, diagnostic findings, and surgical management of zygomatic sialadenitis associated with retrobulbar disease in a dog following extensive dental extractions.

A 10-year-old spayed female Cavalier King Charles Spaniel.

The dog was evaluated for acute-onset right-sided exophthalmos that developed after a recent dental procedure involving 15 extractions. Ophthalmic examination identified marked exophthalmos, pain on opening of the mouth, lagophthalmos, and a superficial corneal ulcer. Computed tomography (CT) of the head was performed and revealed a tubular fluid-filled structure likely consistent with a retrobulbar abscess and right-sided zygomatic sialadenitis. Samples for cytology and culture were obtained. Initial medical management included intravenous fluids, broad-spectrum systemic antibiotics, analgesics, topical antibiotics, and ocular antihypertensive medications.

Cytology revealed septic suppurative inflammation. Microbial culture identified Bacteroides pyogenes , an anaerobic organism not typically associated with antimicrobial resistance. Histopathology confirmed subacute zygomatic sialadenitis with associated cellulitis. Due to progressive clinical deterioration and vision loss, transpalpebral exenteration with zygomatic sialoadenectomy was performed. Postoperative recovery was uneventful, with complete resolution of periocular swelling and pain on follow-up examination.

Zygomatic sialadenitis should be considered a differential diagnosis for retrobulbar disease in dogs, particularly when cases are refractory to medical management. In this case, persistent salivary secretions likely contributed to ongoing inflammation and clinical signs. Advanced imaging facilitated accurate diagnosis, and surgical removal of the affected gland was necessary for definitive resolution.