Applying the three R’s to animal experiments in Canada

5. Animals in science

The Canadian Council on Animal Care emphasizes the “3Rs” (Reduction, Refinement and Replacement) to minimize harms to animals used in science, and it requires Animal Care Committees to apply the 3Rs when they evaluate experimental plans. Use your ingenuity (and perhaps some reading on pain and stress in animals) to suggest how the 3Rs might be applied to the following experiment. For each of the 3Rs, suggest how it might be used to improve the experiment or why it cannot be applied. Try to come up with four or five good ideas and state which ‘R’ is being applied in each case. Be sure to comment on all three Rs.

The Canadian Food Inspection Agency (CFIA) has announced a regulatory amendment that requires all cattle to be ear-tagged with a radio frequency identification tag before leaving their farm in order to establish a trace-back system. In addition, it is common practice to ear-tag dairy calves during the first week of life for identification purposes. Thus, the majority of dairy calves now receive an ear tag in each ear. This involves piercing a 0.5 to 1 cm hole in each ear for the placement of the tags.

The proposed experiment will evaluate whether a local anaesthetic spray (used for athletic injuries), or Emla cream (a topical anaesthetic) is effective in reducing the pain caused by the current method of ear-tagging calves. The calves will be kept in a large group and will be caught individually by a rope lasso thrown around the neck; two experienced animal handlers then catch and restrain each calf while a third handler applies a tag in each ear. In one experiment, half the calves will receive a local anaesthetic spray on both ears before tagging, while the other half receives a control spray on both ears before tagging. A second experiment, half the calves will receive Emla cream in both ears before tagging and the other half will receive a control cream in both ears before tagging. After tagging the animals will be released back to the group.

To monitor pain, observers will watch the animals and record any pain-related behaviour including head-shaking and vocalizing. The animals will also be re-captured 30 minutes after tagging to collect a blood sample that will be used to analyze whether they show higher levels of the stress-related hormone cortisol.

The investigators do not know how many animals will be needed to show a difference, but they expect that calves will be very different in how they respond to tagging, and that the roping itself will cause some vocalizing and other disturbed behaviour. They also expect that different animal handlers may cause different amounts of pain during tagging because of small differences in how they handle the calves.

With these sources of variation, the researchers propose using 100 calves (50 calves per treatment) in each experiment to be sure that any difference between the treatments will be clear.

Marking: Three marks for each of four good ideas for applying the 3Rs intelligently to the proposed experiment. Suggest more than four ideas if you wish, and we will mark the best four. The resulting mark out of 12 will be converted to a mark out of 10.