Leo is a three-year-old peacock who visited the MSU Veterinary Medical Center for cataracts. Both eyes were affected, but his right was more severe—it was completely non-visual. After an examination by the Ophthalmology Service, it was decided to perform a modified evisceration; a surgery to remove most of the eyeball.

And while operating on a dog or cat is an everyday occurrence at the Hospital, a peacock is an uncommon patient. Surgery must be approached from an entirely different angle at each step, including anesthesia.

The Anesthesia Service’s Drs. Sara Taylor and Chris Thibault answer the question: What makes anesthetizing a peacock unique?

Feathers and Fasting

“In general, birds may be anesthetized for various procedures, including diagnostics (radiographs, ultrasound, endoscopy, CT scans) and surgeries (enucleations, fracture repairs),” explains Taylor. “The unique anatomy and physiology of birds make them different to anesthetize compared to dogs or cats.”

She and Thibault enumerate the differences in detail:

• Long feathers: When anesthetizing birds, it’s important to minimize stress and use proper restraint technique to prevent injury to the wings and the long train in peacocks.
• Fasting: Birds are typically not fasted more than a few hours prior to general anesthesia, whereas dogs or cats can be fasted for up to 12 hours.
• Dosage: Birds have a faster drug metabolism and elimination compared to dogs or cats, resulting in higher dosages and more frequent administration.
• Sedation: Birds are usually sedated intramuscularly in the pectoral muscles near the keel or intranasally.

• Anesthesia induction: Once adequately sedated, birds commonly undergo a face mask induction of anesthesia. Birds can be easily intubated with an uncuffed endotracheal tube, as their arytenoids and tracheal opening are easily visible. Birds lack a tracheal ligament and have complete tracheal rings as opposed to dogs or cats that have incomplete tracheal rings with a tracheal ligament. Then, birds are connected to an anesthesia machine and administered an inhalant anesthetic in oxygen for the maintenance of anesthesia. An intravenous catheter can be placed in the cutaneous ulnar vein of the wing and intravenous fluids can be administered.
  
• Monitoring vitals: Vital parameter monitoring is similar between mammals and birds, including electrocardiogram (ECG), heart rate, respiratory rate, capnograph, blood pressure (indirect or direct), and body temperature.
  • Pulse oximetry can be unreliable in birds, as the light absorbed by avian blood cells is different from other species.
  • Heart: Like mammals, birds have a four-chambered heart, but have faster heart rates and a higher blood pressure than dogs or cats.
  • Lungs and breathing: Birds have a different pulmonary system compared to dogs or cats. The avian lungs are small and fixed to certain bones like the ribs. Birds lack a diaphragm and require muscle contractions to move the sternum to allow inspiration and expiration to occur. In addition, birds have thin air sacs that direct air flow into the lungs for gas exchange. When ventilating an anesthetized bird, caution must be used not to cause damage or rupture to the air sacs. Peacocks have long necks which need to be supported during the anesthetic event to ensure patency of airway and prevent injury.

“These are just a few of many differences between avian and mammalian anesthesia,” Taylor says.

Leo Post-op

Leo recovered well from a successful surgery. At home, he receives medication in his remaining eye twice daily, and has been reintroduced to another member of the flock, Lea the peahen. He enjoys regular sunshine in a small aviary that lets him see the others in the flock.

"I’m so thankful for the team’s skill and handling of him,” says Leo’s owner, veterinary technician Cathy Winters.