Meningeal Granular Cell Tumour in a Green Tree Python (Morelia viridis).

Granular cell tumours (GCTs) are uncommon neoplasms mostly reported in man, dogs and horses. The origin of GCT is thought to be Schwann cells, with the associated characteristics of neural crest morphology. Neoplastic cells often demonstrate positive immunoreactivity for S100, LC3, vimentin and p62. They are also periodic acid-Schiff (PAS) positive and diastase resistant. A female green tree python (Morelia viridis) was presented for severe constipation and hyporexia of 4 month's duration and, despite treatment, died the next day. A 4.8 × 3.4 mm intracalvarial GCT was identified, compressing the overlying cerebrum without invasion. Neoplastic cells were immunoreactive to S100 and had brightly eosinophilic cytoplasmic granules that were PAS positive and diastase resistant. Electron microscopy revealed numerous cytoplasmic lysosomes in neoplastic cells. GCTs are reported rarely in non-mammalian species with three reports in birds. This represents the first report of a GCT in a reptile.

Endocardiosis in Tetras (Family Characiformes).

Proliferative, myxomatous change was identified in the cardiac valves (i.e. valvular endocardiosis) with extension into some cardiac walls (i.e. mural endocardiosis) of five tetras (four neon tetras [Paracheirodon innesi] and one rummynose tetra [Hemigrammus rhodostomus]). Review of cardiac sections from tetras (family Characiformes) submitted to two diagnostic laboratories revealed a prevalence of endocardiosis in tetras of 4.3% and 5.7%, respectively. In four cases, concurrent disease that could be a primary cause of death was not identified, and endocardiosis was considered the primary cause of death; in the fifth case, egg binding was present concurrently. This retrospective case series suggests that endocardiosis is a significant concern in fish of the family Characiformes.

Pulmonary Veno-Occlusive Disease: A Newly Recognized Cause of Severe Pulmonary Hypertension in Dogs.

Pulmonary hypertension is a well-known though poorly characterized disease in veterinary medicine. In humans, pulmonary veno-occlusive disease (PVOD) is a rare cause of severe pulmonary hypertension with a mean survival time of 2 years without lung transplantation. Eleven adult dogs (5 males, 6 females; median age 10.5 years, representing various breeds) were examined following the development of severe respiratory signs. Lungs of affected animals were evaluated morphologically and with immunohistochemistry for alpha smooth muscle actin, desmin, CD31, CD3, CD20, and CD204. All dogs had pulmonary lesions consistent with PVOD, consisting of occlusive remodeling of small- to medium-sized pulmonary veins, foci of pulmonary capillary hemangiomatosis (PCH), and accumulation of hemosiderophages; 6 of 11 dogs had substantial pulmonary arterial medial and intimal thickening. Ultrastructural examination and immunohistochemistry showed that smooth muscle cells contributed to the venous occlusion. Increased expression of CD31 was evident in regions of PCH indicating increased numbers of endothelial cells in these foci. Spindle cells strongly expressing alpha smooth muscle actin and desmin co-localized with foci of PCH; similar cells were present but less intensely labeled elsewhere in non-PCH alveoli. B cells and macrophages, detected by immunohistochemistry, were not co-localized with the venous lesions of canine PVOD; small numbers of CD3-positive T cells were occasionally in and around the wall of remodeled veins. These findings indicate a condition in dogs with clinically severe respiratory disease and pathologic features resembling human PVOD, including foci of pulmonary venous remodeling and PCH.

Unusual Necrotizing Encephalitis in Raccoons and Skunks Concurrently Infected With Canine Distemper Virus and Sarcocystis sp.

Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the United States. Due to the immunosuppressive effects of the virus, concurrent opportunistic infections are also common. Among these, secondary systemic protozoal infections have been described in a number of species. We report an unusual presentation of necrotizing encephalitis associated withSarcocystissp in four raccoons and one skunk concurrently infected with canine distemper virus. Lesions were characterized by variably sized necrotizing cavitations composed of abundant mineral admixed with inflammatory cells and protozoa.Sarcocystissp was confirmed via immunohistochemistry using a monoclonal antibody toSarcocystis neurona The pathologic changes are similar to lesions in human AIDS patients infected withToxoplasma gondii.