Metallic foreign bodies in horses' mandibles are rare but challenging, often causing swelling and infection. Advanced imaging and surgical removal are crucial for successful treatment. This report describes a case involving a penetrated wire removed using ultrasound guidance. A 13-year-old Thoroughbred mare was presented with a two-week history of dysphagia, left-sided facial swelling, ptyalism, and anorexia. Clinical examination revealed painful mandibular swelling and foul-smelling breath, suggesting infection or foreign body involvement. Radiography identified a metallic foreign body embedded in the mandibular alveoli between the second and third molars (M2–M3). Ultrasonography further localized the object, revealing surrounding hypoechoic abscessation and regional soft tissue inflammation. Surgical removal of foreign body under deep sedation on standing position was performed, followed by debridement, lavage, and closure. Postoperative management included antimicrobial therapy (penicillin-streptomycin) and anti-inflammatory analgesia (phenylbutazone). The mare showed rapid clinical improvement, with complete resolution of dysphagia and swelling within one week. Follow-up radiography confirmed successful extraction and healing. This case highlights the diagnostic value of combined radiography and ultrasonography in identifying foreign bodies in oral cavity and underscores the importance of prompt surgical intervention for optimal outcomes in equine medicine.