Circumflex left aortic arch: a new vascular ring anomaly in dogs.

OBJECTIVE: To describe the circumflex left aortic arch as a new form of canine congenital vascular ring anomaly leading to esophageal constriction. ANIMALS: 3 large-breed dogs of variable age: a 9-month-old entire male German Shepherd Dog-Rottweiler cross, a 17-week-old entire male German Shepherd Dog, and a 9-year-old neutered female Labrador Retriever, seen between April 2022 and May 2023. CLINICAL PRESENTATION: Dogs presented for chronic postprandial regurgitation and poor growth. One dog presented for a hard mass on the caudal mandibular region. RESULTS: Computed tomography revealed a normal leftward-oriented cranial half and an abnormal caudal half of the aortic arch crossing toward the right dorsal hemithorax leading to esophageal constriction in all dogs. In addition, 1 dog presented with a right patent ductus arteriosus and 1 with an aberrant right subclavian artery. CLINICAL RELEVANCE: Circumflex left aortic arch is a newly discovered rare type of congenital vascular ring anomaly in dogs, which presents a similar anatomical derangement to the human form. Clinical signs include postprandial regurgitation and poor growth. Circumflex left aortic arch vascular anomaly cannot be surgically corrected via the left thoracotomy that is commonly used for the more common vascular ring anomalies in dogs. Computed tomography is a useful diagnostic modality for the diagnosis of this condition, detection of concomitant congenital vascular malformations, evaluation of associated pathologies, and surgical planning.

Learning in the third dimension.

Sharon Boyd, Eoghan Clarkson and Brian Mather explain how the Royal (Dick) School of Veterinary Studies is using the latest 3D modelling techniques to help students develop their clinical skills.

Association of star-shaped poly(D,L-lactide)s containing nucleobase multiple hydrogen bonding.

A new family of associating polymers based on four-arm, star-shaped poly(D,L-lactide) (PDLLA) containing peripheral complementary hydrogen-bonding sites is described. Hydroxy-terminated, four-arm, star-shaped PDLLAs of controlled molar mass were functionalized with complementary DNA base pairs, adenine (A) and thymine (T), to obtain PDLLA-A and PDLLA-T, respectively. 1H NMR spectroscopy confirmed quantitative functionalization and the subsequent formation of PDLLA-A and PDLLA-T hydrogen-bonded complexes. Job's analysis revealed a 1:1 optimal stoichiometry for the hydrogen-bonded complexes, and the association constant (Ka) that was determined using the 1H NMR-based Benesi-Hildebrand treatment was 84 M(-1) for the low molar mass complementary polymers. Furthermore, the PDLLA-based hydrogen-bonded complexes exhibited higher solution viscosities compared to the corresponding non-hydrogen-bonded precursors, which further confirmed strong complementary multiple-hydrogen-bonding associations between the star-shaped polymers with terminal adenine and thymine groups. Moreover, variable-temperature 1H NMR studies demonstrated the thermoreversibility of the hydrogen-bonded PDLLA-based complexes in solution.