Objective—To follow the development of the refractive
error in the eyes of ostrich chicks from age 0 to
day 37 after hatching.
Animals—35 ostrich chicks.
Procedures—Spot retinoscopy was conducted to
assess refractive error in ostrich chicks. Seventy eyes
of 35 ostrich chicks were examined. Of these, 18
chicks were followed over time. At least 4 serial measurements
(at 2- to 7- day intervals) were conducted
in each of these chicks from day 1 to 37 after hatching.
Seventeen additional chicks were examined on
days 0, 3, 12, and 19 after hatching.
Results—Ostrich chicks were myopic at hatching,
with a mean ± SD refractive error of −4.47 ± 0.15
diopters (D). The refractive error rapidly decreased
during the first week of life, and by day 7 after hatching,
chicks were slightly hyperopic, with a mean
refractive error of 0.42 ± 0.12 D. After day 7, there
were no significant differences in the mean refractive
Conclusions—The development of optics in the
ostrich eye appears to be unique among animals and
is characterized by myopia at hatching, rapid onset of
emmetropia, and minimal variation in refractive error
among chicks. (Am J Vet Res 2001;62:812–815)
Objective—To establish an anesthetic protocol suitable for surgical interventions in hippopotami (Hippopotamus amphibius).
Design—Prospective case series.
Animals—10 adult male hippopotami undergoing castration.
Procedures—A combination of medetomidine (60 to 80 µg/kg [27.3 to 36.4 µg/lb]) and ketamine (1 mg/kg [0.45 mg/lb]) was administered IM on the basis of mean estimated weights of 1,330 ± 333 kg (2,926 ± 733 lb; median, 1,350 kg [2,790 lb]; range, 900 to 2,000 kg [1,980 to 4,400 lb]). Monitoring included sequential blood gas analyses, pulse oximetry, and capnography. Reversal of anesthesia with atipamezole (0.34 ± 0.06 mg/kg [0.15 ± 0.027 mg/lb]; median, 0.33 mg/kg [0.15 mg/lb]; range, 300 to 500 mg total dose]) was uneventful and rapid in all cases.
Results—Complete immobilization and a surgical anesthetic plane were achieved 27 ± 11.8 minutes (median, 24.5 minutes [range, 14 to 44 minutes]) after initial injection. Anesthesia (97.3 ± 35.3 minutes; median, 95 minutes [range, 57 to 188 minutes]) was maintained with 3.4 ± 2.2 (median, 3) additional doses of ketamine (0.1 to 0.4 mg/kg [0.045 to 0.18 mg/lb]). Transitory apnea of 4.71 ± 2.87 minutes (median, 4 minutes [range, 1 to 9 minutes]) was documented in 5 animals. Apnea during anesthesia was viewed as a physiologic condition in this semiaquatic mammal because related vital parameters (heart rate, pH, peripheral hemoglobin oxygen saturation as measured by pulse oximetry, venous partial pressure of CO2, and lactate and HCO3 concentrations) remained unchanged and did not differ significantly than those parameters for the 5 animals with continuous respiration.
Conclusions and Clinical Relevance—Both in captivity and in the wild, common hippopotami are difficult to anesthetize. The combination of medetomidine and ketamine provided an excellent surgical plane of anesthesia and a self-limiting dive response.