Table 1.

Clinical scoring system of anesthesia depth in horses [modified from Hubbell and Muir (17)].

Anesthetic plane	Clinical score	Pupil position/size	Eye reflex (P, palpebral; C, corneal)	Heart rate/blood pressure/(spontaneous respiration)
Too light	4	Central/large or small	P: active; C: active	Normal or elevated/breathing against ventilator; occasional swallowing
Medium	3	Ventromedial/small or medium	P: depressed; C: mildly depressed	Normal or minimally depressed
Medium–deep	2	Central/medium	P: depressed; C: depressed	Minimally to moderately depressed
Too deep	1	Central/large	P: absent; C: markedly depressed	Markedly depressed

A mean arterial pressure (MAP) >90 mmHg was presumed as “elevated,” a MAP ≤90 and ≥70 mmHg as “normal,” a MAP <70 and ≥65 mmHg as “minimally depressed,” a MAP <65 and >60 mmHg as “moderately depressed,” and a MAP ≤60 mmHg as “markedly depressed”.

A heart rate (HR) >45 beats per minute (bpm) was supposed to be elevated, a HR between 30 and 45 bpm was thought to be normal, and a HR <30 bpm was thought to be depressed.