Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, B.C., Canada.
Sci Rep. 2018 Jun 21;8(1):9443. doi: 10.1038/s41598-018-27669-7.
We assessed aversion to injections using an avoidance-learning paradigm. Holstein calves (n = 24) were randomly assigned to one of four routes of administration for 0.5 ml of saline: intramuscular (IM), intranasal (IN), subcutaneous (SC) and a null control. Calves were first trained to approach a milk reward of 1 L. Once the latency to approach the reward was consistent, calves received their assigned treatment when approaching the bottle. For the first 3 treatment sessions calves received a 1 L milk reward. This reward was then reduced to 500 mL, and then to 250 mL, and finally to 0 mL, each for 3 sessions. Compared to control calves, calves receiving the intramuscular injections showed a longer latency to approach the milk reward, but only when the milk reward was 0.25 L (P = 0.05) and 0 L (P < 0.01). Calves receiving the intranasal injections showed longer latencies relative to the controls only for the 0 L reward (P = 0.01). Calves receiving the subcutaneous injections did not differ from controls for any of the milk rewards (P > 0.2). We conclude that IM injections are aversive and that SC and IN routes are a refinement to be considered when feasible.
我们使用回避学习范式来评估对注射的厌恶感。荷斯坦小牛（n=24）被随机分配到四种不同的给药途径之一，接受 0.5ml 生理盐水：肌肉内（IM）、鼻内（IN）、皮下（SC）和空白对照。小牛首先接受训练，以接近 1L 的牛奶奖励。一旦接近奖励的潜伏期保持一致，当小牛接近奶瓶时，就会给予它们指定的治疗。在前 3 次治疗中，小牛会获得 1L 的牛奶奖励。然后，该奖励减少到 500mL，然后再减少到 250mL，最后减少到 0mL，每次减少 3 次。与对照组相比，接受肌肉内注射的小牛在接近牛奶奖励时表现出更长的潜伏期，但仅在牛奶奖励为 0.25L（P=0.05）和 0L（P<0.01）时如此。与对照组相比，接受鼻内注射的小牛仅在接受 0L 奖励时表现出更长的潜伏期（P=0.01）。对于任何牛奶奖励，接受皮下注射的小牛与对照组均无差异（P>0.2）。我们得出结论，肌肉内注射是令人厌恶的，而 SC 和 IN 途径是可行时需要考虑的改进方法。
