Evaluation of thoracic duct ligation and unilateral subphrenic pericardiectomy via a left fourth intercostal approach in normal canine cadavers.

OBJECTIVE: To investigate a left-sided fourth intercostal approach to thoracic duct (TD) ligation and unilateral subphrenic pericardiectomy in dogs. STUDY DESIGN: Retrospective computed tomography (CT) review and cadaveric study. ANIMALS: Thirteen dogs with idiopathic chylothorax and 10 canine cadavers. METHODS: A retrospective study of CT lymphangiograms in client-owned dogs with idiopathic chylothorax evaluated location and branching of the TD at the left fourth intercostal space. A cadaveric study evaluated the efficacy of TD ligation at this site. Following methylene blue mesenteric lymph node injection, TDs were identified through a left fourth intercostal thoracotomy, ligated, and sealed. Unilateral subphrenic pericardiectomy was performed through the same incision. Computed tomography scans were performed to determine the success of TD ligation. RESULTS: A review of lymphangiograms revealed a single TD in 10/13 clinical cases at the fourth intercostal space. Three cases had additional branches. Thoracic duct ligation via a left fourth intercostal thoracotomy was successful in nine out of 10 cadavers. A single branch was noted intraoperatively in six out of 10, and two branches were noted in four out of 10 cadavers. All branches were observed on the left side of the esophagus. CONCLUSION: TD ligation at the left fourth intercostal space was successfully performed in 9/10 canine cadavers and appeared feasible in a retrospective review of 10/13 clinical cases. Unilateral subphrenic pericardiectomy can also be performed via this approach. CLINICAL SIGNIFICANCE: Fewer thoracic duct branches at this location in comparison with the standard caudal location may simplify TD ligation. If elected, unilateral subphrenic pericardiectomy can be performed through the same incision. Further investigation in clinical patients is warranted.

The effects of targeted deletion of cannabinoid receptors CB1 and CB2 on intranasal sensitization and challenge with adjuvant-free ovalbumin.

The mechanisms by which cannabinoid receptors CB(1) and CB(2) modulate immune function are not fully elucidated. Critical tools for the determination of the role of both receptors in the immune system are CB(1)/CB(2) double null mice (CB(1)/CB(2) null), and previous studies have shown that CB(1)/CB(2) null mice exhibit exaggerated responses to various immunological stimuli. The objective of these studies was to determine the magnitude to which CB(1)/CB(2) null mice responded to the respiratory allergen ovalbumin (OVA) as compared with wild-type C57BL/6 mice. The authors determined that in the absence of adjuvant, both wild-type and CB(1)/CB(2) null mice mounted a marked response to intranasally instilled OVA as assessed by inflammatory cell infiltrate in the bronchoalveolar lavage fluid (BALF), eosinophilia, induction of mucous cell metaplasia, and IgE production. Many of the endpoints measured in response to OVA were similar in wild-type versus CB(1)/CB(2) null mice, with exceptions being modest reductions in OVA-induced IgE and attenuation of BALF neutrophilia in CB(1)/CB(2) null mice as compared with wild-type mice. These results suggest that T-cell responses are not universally exaggerated in CB(1)/CB(2) null mice.