Signs of metastatic disease on thoracic radiographs of dogs suffering from mammary gland tumours: a retrospective study (1990-1998).

A mammary gland tumour (MGT) was clinically diagnosed in 136 dogs. Histologically 71% were malignant and 29% benign. Intrathoracic metastatic disease was noted or suspected radiographically in 13.5% of the dogs with malignant and in 2.5% of the dogs with benign MGT. Six dogs with malignant MGT were necropsied, 5 had pulmonary metastases but only 1 had radiographic signs of intrathoracic metastatic disease. We conclude that radiographs are not very sensitive for detection of early intrathoracic metastatic disease of MGT.