Retroperitoneal haematoma after ultrasound‐guided transmuscular quadratus lumborum block in two dogs

Abstract

Abstract Ultrasound‐guided fascial plane blocks have gained popularity in human and veterinary medicine due to their favourable safety profile and relative procedural ease. Among these techniques, the quadratus lumborum (QL) block provides effective somatic and visceral abdominal analgesia while maintaining superior haemodynamic stability compared to traditional neuraxial techniques. Although ultrasound guidance may enhance safety and accuracy, complications such as vascular puncture and haematoma formation can still occur. This report details two cases of accidental retroperitoneal haematoma occurring as a complication following bilateral ultrasound‐guided transmuscular QL block in dogs undergoing abdominal surgery. In both dogs, no complications were observed perioperatively and rescue analgesia was not required. These cases emphasize the importance of patient selection, anatomical knowledge, careful needle placement and postoperative monitoring to minimize potential risks. Further research is needed to define incidence and risk factors for vascular complications associated with the QL block in veterinary patients.