Emergency surgeries always keep things interesting. On Friday, when attempting to move a Cooper’s hawk into a larger enclosure for exercise, we found that she was suffering from severe open-mouth breathing/dyspnea.
[Back story: This patient, #17642, was admitted 25 days ago and diagnosed with emaciation. We stabilized her; she gained weight and strength, and was doing remarkably well. We assumed she would be a quick turnaround.]
We rushed her inside and immediately placed her on oxygen. This did not help. Dr. Scott then placed a red-rubber air sac tube through the left paralumbar fossa (lower abdomen). This definitely seemed to help and the tube flowed nicely. He then performed an endoscopy to see if he could find the cause of the labored breathing in the trachea. Perhaps a blockage. We discovered a yellow, friable glob just inside glottis. We were able to remove that with normal forceps. We passed the scope in further and found the lumen to be very stenotic (narrowed/blocked). It was only about 20-25 percent open and it appeared to be scar tissue. We attempted to remove some of the mass with the 1mm forceps. It bled a lot but we could not remove any of it. We tried infusing some epinephrine to see if it would shrink but that didn’t help.
Next step: surgery. Dr. Scott made a full thickness incision through the trachea. He then removed the section of trachea that was thickened and then reconnected the healthy ends. Think of it as splicing a garden hose. The patient recovered quickly and spent the night indoors.
She is now in a small outdoor enclosure, eating well, but still having some difficulty breathing. This isn’t unexpected during the healing process, plus she most likely has some fluid in her lungs from the procedures. Yesterday we had to place a second air sac tube to help her (a second “snorkel” or “smoke stack”, as we call them, jokingly). Prognosis is still extremely guarded, but she is very active and alert so we are taking it day by day. The diagnosis was tracheal stenosis.
So, why did this happen to her? Most likely the scar tissue was caused by a previous trauma. When the trachea is damaged, it really likes to scar. That’s one reason we are really worried about the surgery-even the incisions that were made to remove the scarring will eventually scar.
How is she able to breathe through the tubes in the side of her body? The avian respiratory tract is very different from mammals. They have uniquely avian anatomical features called air sacs. The air sacs are balloon-like structures at the “ends” of the airway system. Birds ventilate their lungs not by expanding the lungs themselves, but by expanding the air sacs. The air sacs are not involved in oxygen exchange, but they act as “bellows” to direct air flow into and through the lungs, and also to hold part of the total volume. Avian lungs are stiff, not at all like the inflatable lungs of mammals. So, when the natural airway, or trachea, is obstructed, we are able to create a new, temporary airway through an air sac.