Background: Severe and complex angular limb deformities in dogs require accurate morphological assessment using diagnostic imaging to achieve successful orthopedic surgery. Computed tomography (CT) is commonly used to overcome projection errors in two-dimensional angular measurements of dog hindlimb alignment. Three-dimensional volume rendering (VR) techniques permit virtual positioning and variable projection, but the final CT-image that defines the projection plane for angular measurements remains two-dimensional. Objective: We wanted to develop a true three-dimensional open-source technique to measure the alignments of the hind limbs of dogs in CT scanners. Methods: We developed an open-source 3D Slicer plug-in, to perform angular measurements using vector calculations in three-dimensional space. In 113 CT-scans of canine pelvic limbs, femoral torsion, femoral varus, femorotibial rotation, tibial torsion, tibial varus and tibiotalar rotation angles were calculated and compared to an already validated technique using VoXim®. Results: Reference points were identified and measurements were possible in the 113 acquisitions. The greatest difference between the two techniques was 1.4° at only one tibial torsion angle. Mean values for all Bland-Altman plots did not show significant differences and were less than 0.07° for all comparisons. Discussion: Based on these results we considered angular measurements of canine hind limb alignment in CT scans using the 3D Slicer extension program sufficiently accurate for clinical orthopedic and surgical purposes in veterinary medicine. Conclusion: With our open-source 3D Slicer extension software, we provide a free accessible tool for veterinary orthopedic surgeons and thus we hope to improve angular measurements in CT-scans of canine hind limb deformities through true three-dimensionality.

A 2-year-old male neutered domestic shorthair cat was presented with a 12-month history of anorexia, weight loss, vomiting, polyuria, and polydipsia. Physical examination revealed a responsive but debilitated cat with icteric mucous membranes and a low body-condition score. Laboratory tests showed mild macrocytic anemia, elevated liver enzymes, hyperproteinemia with hypoalbuminemia, hyperbilirubinaemia, and a decreased vitamin B12 level. Abdominal ultrasound revealed marked dilation of the common bile duct (CBD) and gallbladder, consistent with suspected extrahepatic biliary tract obstruction, as well as secondary pancreatic and intrahepatic duct distension. Cytological and bacteriological analyses confirmed bacterial cholangiohepatitis due to a mixed infection with Escherichia coli and Peptostreptococcus canis. Despite initial conservative management, the cat’s clinical condition remained unchanged, prompting exploratory laparotomy. Intraoperative findings confirmed the ultrasonographic suspicions and revealed severe pancreatitis. Based these findings, a cholecystectomy, choledochoenterostomy, and placement of a cholecystostomy tube as well as an abdominal drain and jejunal feeding tube were performed. Postoperatively, the cat initially showed improvement but subsequently developed signs of sepsis requiring intensive care. Although temporary stabilization was achieved, the cat died suddenly ten days after surgery due to unknown causes. This case report highlights the diagnostic and therapeutic challenges associated with bacterial cholangiohepatitis secondary to biliary obstruction in cats and documents the first clinical application of choledochoenterostomy—a surgical procedure previously only described hypothetically in this species.