The Blue-Fronted Amazon Parrot (Amazona aestiva) Lacks a Femoral Diverticulum from the Abdominal Air Sac

The respiratory system of birds includes the presence of air sacs distributed around coelomic organs and with internal diverticula into bones, resulting in pneumatization of certain bones such as the vertebrae, keel, ribs, humerus, and, sometimes, femur. Due to the clinical importance of these pneumatized bones in surgical and medical procedures, and the vast diversity in the description among species, this study evaluated the morphology of the femoral diverticulum in the blue-fronted Amazon parrot (<i>Amazona aestiva</i>) to determine if the femur is pneumatized. For this study, barium sulfate was diluted in distilled water to a final concentration of 33 mg/mL and administered into 16 blue-fronted Amazon parrot carcasses that were divided into 2 groups of 8 individuals each. In group A the solution was administered through an endotracheal tube to completely fill the respiratory system, and in group B the contrast was injected through an intraosseous (IO) catheter into the distal epiphysis of the femur. For both groups, serial radiographic imaging was performed, followed by dissection and osteotomy of the femur to detect the presence or absence of a diverticulum inside the bone. This study did not detect a connection between the femur and the respiratory system, with contrast present exclusively in the cardiovascular or respiratory systems when administered through the IO catheter or endotracheal routes, respectively. Additionally, when injected via the femur, the contrast was distributed to the posterior vena cava through the renal circulation, bypassing the renal portal system. Therefore, the femur of blue-fronted Amazon parrots is a medullary bone with the potential to be used for IO cannulation.