For years endoscopy has been used for surgical sexing birds. This has been become less important with the use of alternative sexing methods. However for diagnostic examinations of coelom, trachea and oesophagus, in many cases together with taking a microbiological or histological sample, the importance has been increased.
Lateral Approaches to the Avian Coelom
Place the bird in right lateral recumbency. The left wing should be extended dorsally and taped in place. The birds upper leg now can be pulled caudally. A small incision is made in the skin using a scalpel (approximately 5 to 10 mm ventral of the hip). The muscular layer is afterwards bluntly dissected by means of a small mosquito forceps. A distinct "pop" indicates in most cases the penetration into the air sac. The forceps is opened slightly, to enlarge the hole and the endoscope is entered under visual control. Visualisation should begin as soon as the scope is introduced into the incision.
Examination: lung, air sac, gonads, kidney, urethra, spleen, ventriculus, proventriculus, intestinal loops.
If the upper leg is drawn forward, the posterior point of the sternum is followed dorso-laterally until a notch is felt. This lies between the sternum and the last rib. The skin incision has to be made just caudal where the semitendinosus muscle (m. flexor lateralis) passes over the rib. The shape of the notch and its relative position varies greatly with the species of bird.
Ventral Approach to the Liver
The preferential approach for examination of the liver and taking liver biopsies is through the ventral midline, immediately posterior to the sternum.
The bird is placed in dorsal recumbence. A skin incision is made 1cm caudal to the sternum in the midline. A forceps should be entered bluntly to prevent liver trauma.
Examination: Liver, pericardium, air sac.
The inside of the beak, choana, tongue, and larynx can be easily examined using an endoscope.
For endoscopic examination of the upper respiratory tract the bird has to be placed in sternal recumbence and his neck has to be fully extended. Especially in smaller birds with severe respiratory disorders it is much safer to let the bird breath through a tube inserted into the abdominal air sac. Depending on the size of the bird and the length of the endoscope, the tracheal bifurcation may be examined.
In this procedure the neck has to be extended, so that the oesophagus is as straight as possible. In most cases visualisation is much better on the way up from the crop, because of mucus and ingesta. All manipulations have to be done very gently. Visualisation of the crop and oesophagus can be enhanced by insufflations of the crop using a soft rubber feeding tube.