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Lung Tumours Most lung tumours in the dog arise as a result of tumour spread from other tissues, such as mammary glands, bone, abdominal organs or skin. Tumour spread occurs through the blood and tissue fluid. Of those tumours which do originate in the lungs the most common is the pulmonary adenocarcimoma, most of these are malignant, and the majority occur in animals older than 11 years. The clinical signs often start with coughing and increased respiratory rate. In most cases these do not respond to initial therapy, and are of increasing severity until severe respiratory difficulty develops. General lethargy, fever, weight loss, chest pain (manifest as reluctance to move), and lameness (due to the development of h ) can also be part of the presenting picture. Harsh respiratory sounds develop, and pleural effusion can collect between the chest wall and the lungs. To diagnose this condition it is essential to X-ray the chest, the tumours may appear as single or multiple distinct masses, or as a diffuse pattern spread throughout the lung fields. Before any single mass can be detected on x-ray it has to have a diameter of at least 5mm. If it is necessary to determine the specific type of tumour involved then cytology of the bronchial exudate, or even a needle biopsy taken across the chest wall can be used. Treatment is limited. In those cases where the mass is solitary surgery to remove the affected lung lobe may be attempted, however the high likelihood of tumour spread warrants a grave prognosis. Chemotherapy has not had encouraging results. Radiotherapy of pulmonary tumours has not been properly evaluated in dogs. In most cases when quality of life begins to deteriorate then euthanasia becomes the most likely outcome. |
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