Would I let my own DD at 3-4 witness this? Tough question. I'm going to go with "no."
On one hand, I try to let her take her interest wherever they're going. But here's where I have an issue with this particular scenario: The clinical environment is less than ideal, which is leading her to witness some unnecessary animal suffering. There's a subtext here that even though these animals are being hurt, it's in their own best interests, and the activity is endorsed by the adults in her life. I leave it to your imagination how a 3yo can misinterpret these messages and apply the information.
Of course, this message can be managed by how the adults react to the situations where the animal is being hurt. If the adults are expressing guilt, frustration at the lack of proper facilities, and explaining how, in a perfect world, the procedure should have gone, then the child can get a more accurate interpretation of the events around her.
With the potential risks outweighing the benefits, I'm sticking with "no."
