EVALUATION OF PROGNOSTIC FACTORS FOR DOGS WITH PRIMARY LUNG-TUMORS - 67 CASES (1985-1992)

Objective-To determine associations between clinical and histologic fa ctors in dogs with primary lung tumors and outcome and to develop a hi stologic grading method for primary lung tumors. Design-Retrospective study. Animals-67 dogs undergoing thoracotomy and lobectomy for primar y lung tumors. Procedure-Medical records and histologic sections were reviewed to evaluate factors of prognostic importance. Association of these factors with disease-free interval (DFI) and survival time was e valuated, using the Cox proportional hazards model. Median DFI and sur vival time were determined, using the Kapian-Meier product-limit metho d. Results-Clinical and histologic factors significantly associated wi th prognosis were histologic score, detection of clinical signs, and m etastasis to regional lymph nodes. On the basis of histologic score, a histologic grading method was developed. Dogs with well-differentiate d tumors had significantly longer survival time and DFI (median DFI, 4 93 days) than dogs with moderately (median DFI, 191 days) or poorly (m edian DFI, 0 days) differentiated tumors. Dogs with clinical signs or metastasis to regional lymph nodes had shorter survival times and DFI than dogs in which lung masses were discovered as an incidental findin g. Clinical Implications-Dogs with well-differentiated, nonmetastasize d, primary lung tumors that do not have clinical signs associated with the tumor have a favorable prognosis. Dogs with more advanced disease or aggressive tumors histologically may require treatment, such as ch emotherapy in combination with surgery. The grading method proposed he re for primary lung tumors may be useful in other dogs with primary lu ng tumors.