Efforts to induce a general state of anesthesia can be traced back to as early as 4000 BCE. Prior to the development of modern anesthesia, surgical treatments were often avoided by people due to a lack of pain management. Scientific discoveries of the late 18th and the early 19th centuries eventually led to the development of modern anesthetic techniques. By 20th century tracheal intubation and other airway management techniques had become quite common due to the greatly improved safety and efficacy of general anesthesia.
The use of anesthesia in animals was delayed largely due to the misconception that anesthesia induction in animals was unnecessary and painful. However, this ideology was overcome, and veterinary anesthesia became an integral part of animal-based research and investigation procedures. In the 1800s, the potential anesthetic properties of nitrous oxide were suggested by Sir Humphrey Davy which was eventually demonstrated twenty-four years later by H. H. Hickman who mixed nitrous oxide with carbon dioxide to alleviate pain in dogs during surgery. Other drugs and compounds to induce anesthesia were also evaluated in animals. This included diethyl ether, which was extensively used by C. T. Jackson, and chloroform used by Flourens in 1847. In the United States, Dadd (Dadd, 1854) became one of the first advocates of humane treatment of animals and promoted the use of veterinary anesthesia in veterinary surgery. By the end of the 19th century, different routes for anesthetic administrations such as intravenous anesthesia, rectal anesthesia, and intraperitoneal injection were discovered and minimally evaluated. Though the 19th century saw a promising advancement in local analgesic techniques, it wasn’t until well into the 20th century that general anesthesia and humane surgery were adopted into veterinary practices. It can be said that the true beginning of modern era veterinary anesthesia was initiated by the establishment of anesthesia specialty colleges within North America and Europe in the last three decades of the 20th century
Up until the late 19th century, anesthesia delivery did not require a specialized anesthesia machine. However, the introduction of pressurized oxygen and nitrous oxide cylinders required new systems for mounting and delivery. In the year 1917, Henry Edmund Gaskin Boyle designed a continuous-flow anesthetic machine based on the American Gwathmey apparatus of 1912. Since its initial design, Boyle’s machine has seen many improvements and additions to enhance its functions of oxygen delivery, accurate mixing of anesthetic gases and vapors, patient ventilation, and minimization of anesthesia-related risks to patients and staff.
The continuous advancement and investigations in veterinary anesthesiology have revolutionized biomedical research. The expansive research in the field has led to better treatment of laboratory animals and the creation of pain-assessment scales and therapeutic guidelines.