Melanoma of unknown primary origin metastasizing to visceral organs in a sheep

Malignant melanomas are quite uncommon in sheep and goats. A three-year-old native female sheep with a history of sudden death was referred for postmortem examination. Gross evaluations revealed multiple brown to black neoplastic masses with compact nodular appearance, involving lungs, mediastinal lymph nodes, liver and kidneys. Comprehensive physical examination of skin, all mucous membranes and mucocutaneous junctions revealed no evidence of concomitant pigmented lesions or dark discoloration. Microscopically, the masses were predominantly composed of round and polyhedral-shaped neoplastic cells of various sizes with abundant pale eosinophilic cytoplasm containing variable amounts of dark brown melanin pigment and peripherally located, oval to round, vesicular nuclei with prominent nucleoli. Immunohistochemically, the neoplastic cells displayed diffuse and positive expression for S100 protein, vimentin and melan-A. These histopathological and immunohistochemical findings were consistent with a final diagnosis of metastatic malignant melanoma, “epithelioid” type. To the author knowledge, metastatic melanoma without an identified primary origin has not yet been reported in the domestic animals.(AU)

Melanoma of unknown primary origin metastasizing to visceral organs in a sheep

Malignant melanomas are quite uncommon in sheep and goats. A three-year-old native female sheep with a history of sudden death was referred for postmortem examination. Gross evaluations revealed multiple brown to black neoplastic masses with compact nodular appearance, involving lungs, mediastinal lymph nodes, liver and kidneys. Comprehensive physical examination of skin, all mucous membranes and mucocutaneous junctions revealed no evidence of concomitant pigmented lesions or dark discoloration. Microscopically, the masses were predominantly composed of round and polyhedral-shaped neoplastic cells of various sizes with abundant pale eosinophilic cytoplasm containing variable amounts of dark brown melanin pigment and peripherally located, oval to round, vesicular nuclei with prominent nucleoli. Immunohistochemically, the neoplastic cells displayed diffuse and positive expression for S100 protein, vimentin and melan-A. These histopathological and immunohistochemical findings were consistent with a final diagnosis of metastatic malignant melanoma, “epithelioid” type. To the author’ knowledge, metastatic melanoma without an identified primary origin has not yet been reported in the domestic animals.

Acute Mastitis Caused by Pasteurella multocida in a Goat: Clinicopathological and Microbiological Findings

Mastitis is still an important disease causing heavy and irreparable economic losses in the dairy industry. Wedescribe the clinicopathological and microbiological features of an unusual acute septic mastitis caused by P. multocida in a3-year-old dairy goat. At necropsy, the enlargement of the left udder half with hard consistency, the extensive areas ofnecrosis and the accumulations of pus (suppurative exudate) in the cut surface of the affected udder half were observed.Histopathological findings of the affected udder showed severe degeneration and necrosis of the alveolar epithelium and anextensive infiltration of neutrophils within the alveolar lumen. Most of the mammary secretory alveoli were devoid of milkand diffusely filled with basophilic bacterial colonies positively stained by Brown and Brenn method in red color.Microbiological examination of the affected udder revealed P. multocida. It is concluded that P. multocida should beconsidered as an etiological agent of acute septic mastitis in goats.(AU)

Acute Mastitis Caused by Pasteurella multocida in a Goat: Clinicopathological and Microbiological Findings

Mastitis is still an important disease causing heavy and irreparable economic losses in the dairy industry. Wedescribe the clinicopathological and microbiological features of an unusual acute septic mastitis caused by P. multocida in a3-year-old dairy goat. At necropsy, the enlargement of the left udder half with hard consistency, the extensive areas ofnecrosis and the accumulations of pus (suppurative exudate) in the cut surface of the affected udder half were observed.Histopathological findings of the affected udder showed severe degeneration and necrosis of the alveolar epithelium and anextensive infiltration of neutrophils within the alveolar lumen. Most of the mammary secretory alveoli were devoid of milkand diffusely filled with basophilic bacterial colonies positively stained by Brown and Brenn method in red color.Microbiological examination of the affected udder revealed P. multocida. It is concluded that P. multocida should beconsidered as an etiological agent of acute septic mastitis in goats.