Use of Nasotracheal Intubation during General Anesthesia in Two Ponies with Tracheal Collapse.

The research paper discusses the use of nasotracheal intubation on ponies afflicted with tracheal collapse during general anesthesia. The study documents the anesthesia procedures performed on two Shetland ponies suffering from tracheal collapse and requiring eye surgery, with detailed discussion on techniques and postoperative care.

Introduction and Case Background

• Tracheal collapse in ponies presents a significant anesthetic risk due to potential breathing difficulties during anesthesia and recovery. Despite the high incidence and mortality rates in such cases, anesthetic descriptions of such cases are limited.
• The subjects of this study were two Shetland ponies, a 12-year-old male and a 27-year-old female, both suffering from tracheal collapse and referred for right eye enucleation due to severe eye diseases.
• The 12-year-old male showed signs of stress, lung stridor, heightened body temperature, and exhibited difficulty breathing when handled. Radiography confirmed tracheal collapse and inflammation in the lower airways. The 27-year-old female had a history of mitral murmur, esophageal obstructions, and tracheal collapse requiring tracheotomy.

Anesthesia and Surgical Procedure

• Both ponies were premedicated with acepromazine and xylazine to relax and sedate them. Anesthesia was then induced using midazolam and ketamine.
• Nasotracheal intubation was performed in left lateral recumbency, i.e., while the pony was lying on its left side. This was done with the neck and head extended and the process was monitored by capnography which measures the CO2 concentration in respiratory gases.
• The nasotracheal tube used for intubation was essentially long enough for use; it was created by attaching two endotracheal tubes together.
• The anesthesia was maintained with isoflurane and assisted by volume-controlled ventilation. Pain was managed through a retrobulbar blockade procedure using mepivacaine and lidocaine. The cardiovascular system was supported with lactated Ringer’s solution and dobutamine.

Postoperative Care and Recovery

• After surgery, the ponies were administered xylazine and given oxygen through the nasotracheal tube.
• Recovery was assisted through manual support of the head and tail. Extubation, or removal of the breathing tube, was successful after butorphanol administration, done after approximately one hour in a standing position.
• Both ponies were discharged from the clinic a few days after the surgery, indicative of a successful application of the anesthesia technique and recovery process.