Here I will briefly describe the anatomy, sound production, the procedure itself, after care and the desired results.
Anatomy-In birds, the syrinx, or voice box is located within the chest. It is represented above with the red arrows. The syrinx is a small, flexible piece of the trachea. It does not have the cartilage rings found throughout the trachea. All of this is contained within the clavicular air sac. Birds have many air sacs that help lighten the bird and serve as storage for air. It is possible for birds to exchange air through any of these air sacs. If you would like a more in-depth explanation on bird respiration, follow the link. The yellow triangle is the beak and the pink ovals represents the lungs.
Sound Production– I like to compare the syrinx to a balloon. If you have stretched the neck of a balloon and it make that whistling sound, you can understand how the syrinx works. There are muscles attached to the syrinx that will stretch it and the abdominal muscles force air through it, creating the sound. The way this procedure works is to create an opening on either side of the syrinx to allow the air to escape into the air sac instead of through it, out of the mouth. The blue oval represents this artificial opening.
Procedure– The rooster is anesthetized using injectable drugs. Gas anesthesia cannot be used because the surgery is taking place within the respiratory system. Anesthesia is one of the risks of this procedure, as it is with any other surgery.
The area around the thoracic inlet (where the neck joins the body) is plucked and a small incision is made. Then the clavicular air sac is entered, exposing the trachea, heart, lungs etc within the chest.
The syrinx is entered and the split is created. I have built some very specific instrument to create the opening in syrinx that have increased the success of the surgery substantially.
The skin is closed with 2-3 small, dissolvable stitches and a piece of gauze is stitch over the now closed incision.
After Care– The gauze that is stitched in place is removed after 1 day. It seems that the end results are better if the rooster’s crowing is minimized. This may be accomplished by keeping him away from the other birds and/or placed in a short cage inside away from the sounds of the flock. The short cage discourages him from stretching his neck out to crow. The stitches dissolve after a couple of weeks. The feathers grow back quickly and it leaves them looking like before the surgery.
Desired Results– The goal of this procedure is to leave a permanent opening in either side of the syrinx to allow the air to pass into the air sac. This does not seem to cause any pain or discomfort to the rooster. The rooster still crows, cackles, fights, mates etc. I feel that if it was painful, the rooster would not try to crow. This does not seem to really impact his life except he is just quieter. I believe that young, pre-crowing roosters have a higher success rate because they have less inflammation to the syrinx which may lead to scar tissue build up. That is why it is recommended to try and reduce the amount of crowing post surgery.