To investigate and characterise the incidence of iatrogenic complications secondary to closed chest cardiopulmonary resuscitation in dogs. Necropsy reports and histologic sections of tissues were retrospectively examined from 180 dogs that had received closed chest cardiopulmonary resuscitation to determine lesions associated with resuscitation. The most common complication was pulmonary haemorrhage (81/163, 49.7%, 95% confidence interval: 42.1 to 57.3), although only nine dogs had pulmonary haemorrhage of at least moderate severity. Liver fractures occurred in 16 of 180 cases (8.9%, 95% confidence interval: 5.5 to 14.0). Blood loss of >15% of blood volume into the abdomen and/or thorax occurred in 13 of 180 cases (7.2%, 95% confidence interval: 4.2 to 12.1). Significant haemorrhage secondary to cardiopulmonary resuscitation may decrease the chances of achieving the return of spontaneous circulation or may cause or compound ischemic damage to critical organs if the return of spontaneous circulation is achieved. Following successful cardiopulmonary resuscitation, animals should be screened for cavitary or pulmonary haemorrhage, as significant haemorrhage could be a factor in recurrence of cardiac arrest.