Effect of a single dose of tranexamic acid on perioperative blood loss in dogs undergoing spinal surgery.

OBJECTIVE: To determine whether a single preoperative injection of tranexamic acid (TXA) reduces blood loss in dogs undergoing spinal surgery. STUDY DESIGN: Prospective, randomised, blinded clinical study. ANIMALS: One hundred and one dogs scheduled for spinal surgery at The Small Animal Hospital at The University of Glasgow were enrolled between November 2023 and November 2025. METHODS: Anaesthesia technique was chosen by the attending anaesthetist and was not standardised. Dogs were randomly allocated to be administered either TXA (15 mg kg-1, intravenously) or an equivalent volume of Hartmann's solution (control). Block randomisation was based on surgical procedures (ventral slot, dorsal laminectomy, hemilaminectomy, or complex hemilaminectomy). Blood loss was estimated using an established gravimetric clinical system. The primary preregistered outcome measure was total blood loss in mL kg-1. Secondary outcomes were blood loss exceeding 10% of blood volume and clinical requirement for unblinding. Statistical significance was set at p < 0.05. RESULTS: Mean (± standard deviation) blood loss in the control group was 3.70 ± 4.49 mL kg-1versus 3.20 ± 5.03 mL kg-1 in the TXA group, without statistical or clinical differences (p = 0.459). Treatment allocation unblinding occurred in 11 dogs in the control group versus 12 in the TXA group. Blood loss exceeding 10% of estimated blood volume occurred in 13/101 dogs (seven control, six TXA group). CONCLUSIONS: A single preoperative injection of TXA at 15 mg kg-1 did not result in a significant reduction in blood loss during spinal surgery. CLINICAL RELEVANCE: Preoperative injection of TXA at 15 mg kg-1 did not reduce perioperative blood loss in this population. As such, routine use in all dogs undergoing spinal surgery is not supported by these data. Future work should focus on identifying the patient groups and dosing protocols in which TXA may offer measurable clinical advantage.