33rd Annual Scientific Meeting proceedings

Introduction: Trauma and surgical procedures at the equine mandible bear the risk of damage to the parotic salivary duct, which can result in fistula formation. Treatment options include surgical repair of the lacerated duct, surgical removal of the gland, duct ligation or chemical ablation of the gland. The use of 10% formalin is currently recommended for chemical ablation.

Case Description: A two-year-old quarter horse gelding was presented with a chronic wound at the horizontal part of the right mandible. Computer tomography revealed bony sequester formation. Surgical treatment included sequestrectomy, debridement, lavage and primary closure. Postoperatively, the horse developed intense salivary leakage of the wound during food intake. Chemical ablation of the parotic gland using 10% formalin was achieved, followed by continuous decrease in salivary outflow.

Results: Two weeks post injection, the horse was referred to the clinic due to acute bleeding from the right nostril. During emergency examination, the horse developed fatal haemorrhage from the right guttural pouch orifice and subsequently had to be euthanised. Necropsy showed severe necrotic inflammatory processes in the region of the right salivary gland and the lateral wall of the corresponding guttural pouch.

Discussion/ Conclusion: Formalin was shown to cause the least inadvertent reactions compared to other agents. However, formalin injection induces severe inflammation and necrosis of the parotic glandular tissue. Life-threatening complications can occur due to the close anatomical relation of the salivary gland and the lateral wall of the guttural pouch.