Intermittent positive-pressure ventilation (PPV) is an invasive means of respiratory support that is indicated in animals with central and peripheral neuromuscular disease, as well as in those with primary disorders of the lung parenchyma. We reviewed the medical records of 34 dogs and 7 cats treated with PPV. The animals could be allotted to 2 groups; group 1 (21/41) had primary failure of ventilation attributable to neuromuscular disease or airway obstruction, and group 2 (20/41) had primary pulmonary parenchymal disease. Mean inspiratory time was 1.02 +/- 0.2 seconds (range, 0.6 to 1.5 seconds). Mean inspiratory flow was 26.9 +/- 18.5 L/min (range, 7 to 87 L/min), and was positively correlated with body weight (R = 0.57). Mean set respiratory rate was 19.6 +/- 10 breaths/min (range, 5 to 60 breaths/min), with mean tidal volume of 15.5 +/- 6.2 ml/kg of body weight. Positive end-expiratory pressure (PEEP) was required in 14 of 20 dogs in group 2. Mean peak airway pressure in group 1 was 21.6 +/- 6.3 cm of H2O, whereas in group 2 it was 32.9 +/- 12.5 cm of H2O. The higher peak airway pressure in group-2 dogs reflected poor lung compliance and the use of PEEP in dogs with parenchymal lung disease. Mean duration of PPV was 28.2 +/- 29.4 hours (range, 2 to 137 hours). The overall survival rate was 39% (16/41).(ABSTRACT TRUNCATED AT 250 WORDS)