Contrast enhanced computed tomography assessment of superficial inguinal lymph node metastasis in canine mammary gland tumors.

Mammary gland neoplasms are predominant in dogs. However, sentinel lymph node (SLN) status assessment criteria have not been established for these cases. In this retrospective, secondary analysis, diagnostic case control study, CT images of 65 superficial inguinal SLNs were obtained before and 1, 3, 5, and 10 min after intravenous administration of contrast agent (iopamidol 370 mgI/mL). The presence and degree of postcontrast enhancement were assessed, by means of the median absolute density value and the maximum absolute density value at any time point in the center and in the periphery of each SLN measured in Hounsfield units (HU), before and after contrast agent administration. These values were compared with histopathological findings postsurgical excision. Receiver operating characteristic analysis was conducted. The absolute density values ranged widely at each time point and within each group of nodes (negative, positive, control group). At all time points, the median density value in the center and in the periphery was significantly higher in metastatic than in non-metastatic SLNs (P ≤ .014). Among the parameters tested, the median absolute density value measured in the periphery of the SLN 3 min after injection showed the highest sensitivity, specificity, and accuracy (AUC) (87.5%, 82.1%, and 92.1% respectively), with a cutoff value of 50.9 HU. The maximum absolute density value at any time point in the center and periphery of the SLNs was also significantly higher in metastatic SLNs compared to non-metastatic (P ≤ .001). With a cutoff value of 59.5 HU, the maximum absolute density value in the periphery of the SLN displayed high sensitivity and specificity (87.5% and 89.3%, respectively). The results of this study support the hypothesis that contrast enhanced CT imaging may aid in the assessment of SLN metastasis in dogs with mammary gland neoplasms.

ASSESSMENT OF SENTINEL LYMPH NODE METASTASIS IN CANINE MAMMARY GLAND TUMORS USING COMPUTED TOMOGRAPHIC INDIRECT LYMPHOGRAPHY.

In the staging process of the breast cancer, demonstrating metastasis of the sentinel lymph node (SLN) has an important prognostic value, in both humans and animals. The aim of this prospective case-control study was to determine the diagnostic value of computed tomographic indirect lymphography (CT-LG) for detecting SLN metastasis in dogs with mammary cancer. Thirty-three female dogs with tumors in the abdominal and inguinal mammary glands were prospectively selected and subjected to CT-LG, 1 and 5 min after injection of 1 ml of contrast agent (iopamidol) in the subareolar tissue of the neoplastic and the contralateral normal mammary glands. The pattern of postcontrast opacification, degree of postcontrast enhancement, and size and shape were assessed in 65 SLNs in total and were correlated with histopathological findings. The absence of opacification or heterogeneous opacification 1 min after contrast medium injection showed the highest sensitivity, specificity, and accuracy (93%, 100%, and 98.4%, respectively). In images taken 1 min after injection, an absolute density value lower than 444 Hounsfield units (HU) in the center of the SLN also provided significant sensitivity and specificity (93.8% and 75%, respectively). The size and shape of the SLN (maximum and minimum diameter, maximum/minimum diameter ratio, maximum diameter/height of fifth thoracic vertebral body ratio) showed the lowest sensitivity and specificity. Results of this study support the hypothesis that CT-LG could help in the assessment of SLN metastasis in cases of mammary gland tumors in dogs.

Bilothorax Associated with Bile Peritonitis in a Dog with No Diaphragmatic Disruption: A Case Report.

A 4-year-old intact male mixed-breed dog was presented with vomiting and severe depression of 6-day duration after being struck by a car 2 weeks before presentation. Clinical examination revealed hypothermia, respiratory difficulty, jaundice, and a bicavitary (pleural and peritoneal) effusion. Hematological and biochemical abnormalities included neutrophilic leukocytosis, increased total bilirubin concentration, and increased serum lipase activity. Biochemical and cytological evaluation of both abdominal and thoracic fluids were suggestive of bilious effusions. During celiotomy, a rupture of the cystic duct was observed, which necessitated cholecystectomy. A diaphragmatic rupture was not found. A thoracostomy tube was inserted in the right pleural space, and continuous suction was maintained for 48 hours. The dog was discharged 20 days after surgery and no abnormalities were detected on either blood tests or ultrasonographic examinations of the thorax and abdomen on follow-up examination 7 months after surgery. The presence of a bilothorax should be considered in animals with bile peritonitis, grossly intact diaphragm and pleural effusion. The exact mechanisms of the development of bilothorax are unclear, but the transport of bile through microscopic congenital or acquired weaknesses or defects of the diaphragm, via abdominal lymphatics penetrating the diaphragm and draining into the thoracic lymphatics represent the most probable route.