Wilson Jolaine M, Bunte Ralph M, Carty Anthony J
University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Am Assoc Lab Anim Sci. 2009 Nov;48(6):785-9.
Despite the progressively increasing use of zebrafish (Danio rerio) in research, the most humane method of euthanasia for these fish has not been determined. Contemporary guidance documents state that hypothermia is an unacceptable method of euthanasia. The goal of this study was to compare rapid cooling and tricaine methanesulfonate (MS222) for zebrafish euthanasia. Zebrafish (n = 46) were euthanized by immersion in either an ice-water (4 degrees C or less) bath or unbuffered MS222 solution (250 mg/L; 25 to 30 degrees C). Another cohort (n = 10) was exposed to buffered MS222 to determine whether the acidity of the water alone caused distress. The times from exposure until the animals became unable to swim, right themselves, and death were measured, and signs of distress were recorded. Fish then were placed in a 'recovery tank' of system water to verify that recovery did not occur. Tissues were examined histologically. The mean time for euthanasia was longer and the number of fish exhibiting signs of distress was greater for fish exposed to MS222 than those exposed to chilled water. In addition, 4 of the 23 fish exposed to MS222 regained consciousness in the recovery tank, whereas none of 23 fish exposed to chilled water recovered. No histopathologic changes or evidence of ice crystal formation were seen in either group. In light of the faster time to death and fewer signs of distress in zebrafish euthanized by rapid cooling, we advocate this method as a humane veterinary practice.
尽管斑马鱼（Danio rerio）在研究中的使用日益增多，但对于这些鱼类最人道的安乐死方法尚未确定。当代指导文件指出，低温是不可接受的安乐死方法。本研究的目的是比较快速冷却和三卡因甲磺酸盐（MS222）用于斑马鱼安乐死的效果。将46条斑马鱼通过浸入冰水（4摄氏度或更低）浴或无缓冲的MS222溶液（250毫克/升；25至30摄氏度）进行安乐死。另一组（n = 10）暴露于缓冲的MS222中，以确定仅水的酸度是否会引起痛苦。测量从暴露到动物无法游泳、翻身和死亡的时间，并记录痛苦迹象。然后将鱼放入系统水的“恢复水箱”中，以验证是否不会恢复。对组织进行组织学检查。与暴露于冷水的鱼相比，暴露于MS222的鱼安乐死的平均时间更长，出现痛苦迹象的鱼的数量更多。此外，暴露于MS222的23条鱼中有4条在恢复水箱中恢复了意识，而暴露于冷水的23条鱼中没有一条恢复。两组均未观察到组织病理学变化或冰晶形成的证据。鉴于快速冷却安乐死的斑马鱼死亡时间更快且痛苦迹象更少，我们提倡将这种方法作为一种人道的兽医实践。
