Primary lung tumours are uncommon in the dog, whereas pulmonary metastatic neoplastic involvement is common. We report the pathologic features of pulmonary adenocarcinoma in two dogs (case No. 1:10 -year-old castrated male German Shepherd dog; case No. 2: adult intact male pothound stray dog). Case No. 1 presented with left hind limb paralysis and pain upon walking; it was also positive for heart worm disease. There was no history for Case No. 2 which was euthanized and submitted for disposal under the stray dog control program of the Ministry of Health and the Division of Veterinary and Livestock, Ministry of Agriculture, Lands, Forestry, Fisheries & Environment, Grenada. Post-mortem examination revealed a single pulmonary nodule in both cases with metastasis to the liver and pelvic canal in case No. 1. Histopathologically, all the tumour masses consisted of neoplastic, polygonal to cuboidal epithelial cells with moderate amounts of cytoplasm and a large hyperchromatic nucleus arranged in nests and trabeculae. Immunohistochemically, the epithelial cells possessed keratin-cytokeratin in their cytoplasm. The origin of these tumours from bronchiolar epithelial cells or alveolar type I pneumocyte is suggested. Although the incidence of canine primary lung neoplasms is markedly low, this condition must be considered in the differential diagnosis of pulmonary lesions in older dogs.
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