A 1-year-old female Akita dog was referred for intermittent regurgitation. Computed tomographic angiography (CTA) showed an aberrant right subclavian artery (ARSA), resulting in constriction of the esophagus. After surgical ligation of the ARSA, CTA showed that the ARSA was not enhanced by contrast medium, and that sufficient collateral circulation of the right forelimb was supplied through the vertebral artery. Furthermore, the right and left vertebral arteries merged into the basilar artery at the level of the atlas, and no abnormal expansion of the ventral spinal artery was observed. Overall, we demonstrated the importance of post-surgical CTA for identification of surgical complications, including the formation of abnormal vessel alterations.

Postattenuation neurologic signs (PANS) are serious complications following surgical ligation of congenital portosystemic shunts (cPSS) in dogs, but their pathogenesis remains incompletely understood. We hypothesized that surgical ligation alters hepatic tryptophan metabolism through increased substrate delivery and inflammation, leading to changes in kynurenine pathway metabolites that may contribute to PANS. Ten dogs diagnosed with cPSS between April 2019 and December 2023 underwent surgical ligation. Serum samples were collected preoperatively and on postoperative days 1, 2, and 3. Serum concentrations of quinolinic acid (QA) and 3-hydroxykynurenine (3OHKYN) were measured using ELISA in this retrospective observational study. Dogs exhibiting neurological signs within 3 days postoperatively were classified as having PANS. Serum QA concentrations showed no significant postoperative changes and did not differ between dogs with and without PANS. In contrast, serum 3OHKYN concentrations decreased significantly after surgery (p = 0.002). Dogs that developed PANS had significantly lower serum 3OHKYN concentrations on postoperative day 1 (p = 0.048) and exhibited greater reductions from baseline on postoperative days 1 and 3 (p = 0.024 and 0.017, respectively). These preliminary findings suggest that postoperative reductions in 3OHKYN, rather than increases in QA, are associated with PANS development, indicating that altered tryptophan metabolism may play a role in its pathogenesis and warrant further investigation in larger studies.