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Hydrocephalus has been reported in a variety of species, including the North American black bear (Ursus americanus). This report describes three cases of hydrocephalus in this species from wild bears aged 3–4 mo considered retrospectively from necropsy records of one institution. Clinical signs included cortical blindness and ataxia. Primary gross findings were doming of the skull, gyri compression and flattening, and lateral ventricle dilation. Two cases had severe bilateral ventricular dilation with loss of the septum pellucidum; atrophy of the surrounding corpus callosum; and bilateral periventricular tears involving the caudate nuclei, internal capsule, and adjacent cerebrum. Histologically, the cases with periventricular tearing had severe axonal loss and degeneration, malacia, hemorrhage, and variable periventricular astrocytosis. All cases were likely congenital, given the bears' age and lack of an apparent acquired obstruction.

Blastomycosis (Blastomyces dermatitidis) is a fungal disease that is endemic in the southern United States. This case report illustrates the clinical, MRI and histopathologic findings in a dog with invasion of a retrobulbar blastomycotic lesion into the calvarium. A 5-year-old intact female Weimaraner was referred for a 2-month history of change in behavior and recent onset of visual deficits. Magnetic resonance imaging (MRI) examination revealed a large (5.8 × 2.0 × 2.5 cm) mass extending from the left orbit through a circular defect in the left cranioventral aspect of the calvarium caudally to the level of the pituitary fossa and interthalamic adhesion. The mass was heterogeneously iso- to hypointense on T2-W images, slightly hypointense on T1-W images, did not attenuate on fluid attenuated inversion recovery (FLAIR) images, and did not show evidence of susceptibility artifact on T2*-W gradient recalled echo (GRE) images. Vasogenic edema and associated mass effect were noted. The mass showed strong homogeneous contrast enhancement with well-defined margins and had thickening of the adjacent meninges (dural tail sign). Based on MRI findings a malignant neoplastic process was considered most likely and the patient was placed on oral prednisone to decrease peri-tumoral inflammation. The dog initially improved but was euthanized 3 weeks later for worsening clinical signs. Histopathologic assessment of the mass revealed marked pyogranulomatous optic neuritis with intralesional fungal yeasts consistent with blastomycosis (Blastomyces dermatitidis). To our knowledge this is the first report of invasion of a retrobulbar blastomycotic lesion into the calvarium in a dog.

A 15-year-old male North American cougar (Felis concolor) presented with a 2-day history of anorexia, restlessness, and dyspnea. White blood cell count ( cells/μL) and absolute segmented neutrophil count ( cells/μL) were increased, and BUN (143 mg/dL), creatinine (6.3 mg/dL), and phosphorus (8.5 mg/dL) concentrations indicated chronic renal disease. Thoracic radiographs showed severe pleural and pericardial effusion. During attempts to remove the fluid, cardiac tamponade developed and the cat died. At necropsy, nodular masses decorated the pericardium at the level of the base of the heart. The final microscopic diagnosis was mesothelioma of the pericardium, tunica adventitia of the main pulmonary artery, left auricle epicardium, and left ventricular epicardium. A 15-year-old female cheetah (Acinonyx jubatus) was evaluated for acute respiratory distress. The white blood cell count ( cells/μL) and absolute segmented neutrophil count ( cells/μL) were increased. Radiographically pleural effusion and a cranial thoracic mass were seen. The cheetah was euthanized, and a gross diagnosis of disseminated pleural mesothelioma with thoracic effusion was made. Histologically, pleural mesothelioma was confirmed with local invasion of the lung and pulmonary arterial emboli and infarction. In both cases, a diagnosis of mesothelioma was made based on cellular morphology, microscopic architecture, and neoplastic cell coexpression of cytokeratin and vimentin.