Brachial plexus formation in Jaguarundi (Puma yagouaroundi).

Puma yagouaroundi is a wild felid with wide distribution on the American continent. This paper aims to describe the origin and motor distribution of the nerves of the brachial plexus of P. yagouaroundi and compare the findings with the available descriptions for the Carnivora order. Fourteen brachial plexuses of specimens collected dead on highways were dissected (five males and two females). In most cases (57%), the brachial plexus originated from the ventral spinal branches of C5, C6, C7, C8 and T1. The C7 branch was the one that most contributed to the formation of the plexus nerves (57.7%). Among all dissected nerves, 23.6% were unisegmental and 76.4% plurisegmental. The radial nerve was the thickest and innervated the largest number of muscles, while the caudal pectoral nerve showed the most varied formation. Intraspecific polymorphisms occurred in the plexus, although the distribution of the nerves to the muscles had an evident constancy among the individuals. Due to the similarities, locoregional blocking techniques may consider the same anatomical landmarks stipulated for domestic cats. Comparison with the descriptions of other carnivorans allows speculating a polymorphism at the plexus origin, in contrast to the conservative innervation of the muscles in the order Carnivora.

Myoepithelial cells and extracellular matrix in the cytologic differentiation of canine mammary tumors.

BACKGROUND: Mammary neoplasms are common tumors in intact female dogs. Fine-needle aspiration cytology (FNAC) is a valuable diagnostic tool and has gained some credibility in the diagnosis of mammary tumors in dogs. Prompt classification of canine mammary tumors using cytology would enhance feasibility as a prognostic tool and guide clinical and surgical management. OBJECTIVES: We aimed to examine background elements to differentiate mammary tumors using FNAC. We proposed to distinguish simple from complex and mixed tumors by identifying myoepithelial (ME) cells and different types of extracellular matrix. Additionally, we determined the accuracy of FNAC to differentiate benign from malignant tumors. METHODS: One hundred and one mammary tumors from female dogs were included in this study. We compared FNAC using histopathology as the gold standard. Cellular and background components were evaluated and identified. The cytologic accuracy, sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) for diagnosing malignancy were determined, excluding inadequate samples. RESULTS: The cytologic-histologic agreement was 92.5% for simple carcinomas, 57.9% for complex-type carcinomas, 57.1% for mixed-type carcinomas, 27.3% for carcinosarcomas, and 100% for osteosarcomas. Myoepithelial cells were successfully identified using FNAC. Myxoid and chondroid/osteoid matrix were satisfactorily recognized. Cytologic accuracy, Se, Sp, PPV, and NPV for diagnosing malignancy were 99%, 100%, 83%, 99%, and 100%, respectively. CONCLUSIONS: Chondroid/osteoid matrix was noted in mixed tumors but not in complex tumors. Myxoid matrix, often associated with ME cells, was noted in complex and mixed tumors. Mesenchymal cells were differentiated from ME cells, allowing the distinction of simple carcinomas with scirrhous reaction from complex and mixed tumors.