Table 2. Simple descriptive scores, defined time points and ketamine doses from sedation to end of surgery in 36 ponies undergoing field castration after pre-anaesthetic medication with intravenous (IV) romifidine 100 μg kg^-1 and butorphanol 50 μg kg^-1. Anaesthesia was induced with diazepam 20 μg kg^-1 IV combined with ketamine at either 2.2 mg kg^-1 (Group K2.2, n = 18) or 3 mg kg^-1 (Group K3, n = 18). Ponies received top-up doses of ketamine 0.5 mg kg^-1 IV if required to maintain a surgical depth of anaesthesia for the procedure.

	Group K2.2 (n = 18)	Group K3 (n = 18)	p value
Sedation score	1 (1 - 3)	1 (1 - 3)	0.34
Tactile score	1 (1 - 4)	1 (1 - 3)	0.70
Time from sedation to induction (min)	16.0 ± 0.9	18.3 ± 1.4	0.18
Time from start of induction to lateral recumbency (s)	35.6 ± 1.0	34.6 ± 1.3	0.54
Induction score	1 (1 - 3)	1 (1 - 2)	0.95
Intubation score	1 (1 - 4)	1 (1 - 4)	0.65
Time from induction to testicular local anaesthetic block administration (min)	4.1 ± 1.4	4.1 ± 0.9	0.60
Time from induction to first incision (mins)	7.5 ± 2.3	7.1 ± 2.0	0.68
Time from testicular local anaesthetic block to first incision (min)	3.1 ± 1.7	3.0 ± 1.5	0.59
Surgery score for first testicle	1 (1 - 3)	1 (1 - 3)	0.98
Surgery score for second testicle	1 (1 - 4)	1 (1 - 4)	0.18
Surgery time (min)	13.8 (9.9 – 19.7)	14.1 (9.6 – 33.7)	0.84
Number of ponies requiring ketamine top-up	15	13	0.69
Time from induction to first top-up (min)	13.7 ± 1.4	12.2 ± 0.9	0.40
Total number of ketamine top-ups per pony	3 (0 - 6)	2 (0 - 12)	0.38
Total ketamine dose per pony (mg kg-1)	3.5 ± 1.0	4.3 ± 1.8	0.17

Categorical data (scores) are reported as median (range). Normally distributed continuous data are reported as mean ± SD. Non-normally distributed continuous data are reported as median (range).