['The volume of lung tumor core biopsy specimens has been restricted because of concerns for complications such as bleeding and air leakage. In this animal experiment, we investigated the possibility of larger bore biopsies through the peripheral lung parenchyma.', 'Lung biopsy was done in male domestic pigs (n= 4) under thoracotomy. A single biopsy using a 12-gauge cutting biopsy needle was done with sheath (sheath group, eight biopsies) or without sheath (nonsheath group, eight biopsies). After biopsy, bleeding time, bleeding amount, and positive airway pressure causing air leakage from the insertion site was compared between groups (Mann-Whitney U test). To observe long-term effects in closed-chest animals, percutaneous lung biopsy with the use of a sheath was carried out percutaneously in male beagles (n = 9). The animals were observed for 3 weeks.', 'In the pigs (sheath group) after biopsy, bleeding flowed through the sheath and formed a sheath-molded fibrin plug that secured the insertion site. Bleeding time and amount decreased significantly in the sheath group compared with the nonsheath group (115 +/- 108 versus 295 +/- 150 seconds, P = .018, and 37 +/- 41 versus 98 +/- 72 grams, P= .027, respectively). Air leakage pressure was significantly higher in the sheath group compared with the nonsheath group (37 +/- 6 versus 18 +/- 5 cmH2O, P = .001). In the beagles, no complications such as pneumothorax, hemothorax, or airway bleeding was apparent.'] Is lung biopsy with a 12-gauge cutting needle possible using an insertion sheath in animal models?