Pulmonary fibrosis (PF) is defined as a gradual, interstitial fibrous disease of the lung parenchyma. PF causes collapse of the lung lobe, which can lead to lung lobe torsion of the other side. A 14-year-old male Pekinese dog was referred to the Veterinary Medical Center, Chungbuk National University. The chief complaint was acute dyspnea. The dog had a history of chronic cough, which lasted for 18 months, and the cough had recently deteriorated. Tachypnea was observed on physical examination. As a result of thoracic radiographs, ultrasonography, and computed tomography, lung lobe torsion and collapse were diagnosed. A postmortem examination revealed lung lobe torsion of the left cranial lobe and carnification of the right cranial lobe. Histologically, severe and diffuse interstitial fibrosis with distortion of alveolar architecture and severe congestion and/or hemorrhage were observed in the right cranial lobe and left cranial lobe, respectively. Although the cause of pulmonary fibrosis was undetermined, this case showed a typical lung lobe torsion caused by pulmonary fibrosis.

Canine heartworm disease is typically characterized by the presence of heartworms in the pulmonary artery and, to a lesser degree, the right ventricle. Systemic arterial dirofilariasis is an unusual manifestation of heartworm disease of dogs that results from aberrant migration of Dirofilaria immitis into the peripheral arterial circulation. A three-year-old Jindo dog was referred to the Veterinary Medical Center because of hindlimb lameness, paresthesia of hindlimbs, and interdigital ischemic necrosis. Angiography and ultrasonography were performed, resulting in diagnosis of heartworm infestation. In necropsy, entangled heartworms were present throughout the body, including lungs, kidney, small intestinal lumen, and arteries, in addition to the right ventricle and pulmonary artery. Histologically, lung showed adult heart worms in vessels, organized thrombotic vessels, and interstitial pneumonia featuring type II pneumocyte hyperplasia, thickened alveolar wall, and compressed alveolar spaces. Chronic parenchymal lesions, such as focal or diffuse necrosis, fibrosis, and dystrophic calcification were remarkable in liver and kidney. The current case showed a typical canine systemic heartworm disease caused by aberrant migration of Dirofilaria immitis.

A six-year-old male Pekinese dog was referred to the Veterinary Medical Center, Chungbuk National University because of intermittent vomiting, anorexia, alopecia, and pruritus. Generalized alopecia, pigmentation, and papular erythema in the skin were observed on physical examination. Hematological studies indicated a severe pancytopenia and hypoalbuminemia. A hormone analysis indicated a hyperestrogenemia. A circumscribed mass, measuring approximately 3-4 cm in diameter, was observed on abdominal radiographs. Grossly, the cryptorchid testis was enlarged by a firm and white spherical mass, measuring approximately 3 cm in diameter, which, on its cut surface, was creamy white with hemorrhage. The normal scrotal testis was markedly atrophic and soft. Histologically, the intra-abdominal cryptorchid testis contained abundant fibrous tissue stroma and the stromal tissues were arranged in a tubular pattern in which the neoplastic cells tended to palisade. The cells had poor and pale eosinophilic cytoplasm streaming into the center of the tubules. The nuclei were round to oval and tended to be in a basilar location. Regions of hyperplasia and marked squamous metaplasia were observed in many areas of the prostate. Based on the histological findings, we were able to identify these masses as Sertoli cell tumors, and made a final diagnosis as Sertoli cell tumors through immunohistochemistry methods using inhibin-α, vimentin, and neuron-specific enolase.