Key sample characteristics for birds administered butorphanol or saline (n = 76).

1Mean±SD (range).2Value assigned according to a severity scale of 0–4, where 0 = none, 4 = severe open ulcers (Welfare Quality, 2009).3In those individuals with an identified pathology the prevalence of each pathological ‘type’ was also calculated. Each type was recorded independently (therefore allowing >100% total).