Distal limb cellulitis and Digital Flexor Tendon Sheath effusion secondary to porcupine quill migration in a horse.

A 3-year-old Lusitano gelding was referred to the Ontario Veterinary College for evaluation of distal limb swelling and cellulitis affecting the fetlock–pastern region. On presentation the gelding was mildly anxious, yet all vital parameters where with in normal limits. Physical examination revealed moderate soft-tissue swelling and cellulitis over the left hind fetlock–pastern region, along with moderate effusion of the digital flexor tendon sheath (DFTS). Pain was elicited on palpation of the affected area. A small, rounded scab was detected on the lateral aspect of the proximal pastern, associated with mildly firm surrounding tissue. Digital pulses in the affected limb were increased. The gelding was sound at the walk in a straight line on a hard surface. Ultrasonographic examination confirmed the presence of seven porcupine quills located within the peri-synovial soft tissues of the metatarsophalangeal joint (MTPJ) and DFTS) with one quill identified within the DFTS itself. Surgical treatment consisted of ultrasonographically guided removal of the quills, lavage of the DFTS, and intra-techal administration of antimicrobials. One additional quill was identified; however, ultrasonographic artifacts limited the visualization and precluded extraction during the initial procedure. This quill was successfully retrieved during a second anesthetic procedure performed two days later. Porcupine quills injuries in horses are most frequently reported in the facial region and distal limbs. Due to their capacity for migration, quills can penetrate and damage both soft tissues and synovial structures. This case highlights the critical role of ultrasonography in the diagnosis, localization, and surgical removal of porcupine quills, which was essential to achieving a favourable outcome.