Earlier quoted context omitted.
I think the difference is that in the horse example one presumes the horse does not enjoy it and the aim is to breed the horse. In the dolphin example the dolphin appeared to have a romantic attachment to the lady researcher and thus enjoyed the experience. That's still weird in this day and age.
> the horse does not enjoy it That's a bold statement. I don't even know where to begin, there are so many levels here. Like, why would you even make such a claim? I mean I'm not against the claim per se, but it does not seem like you have any evidence, or that you even looked for it. Seems to come right out of some human moral position instead, one that is not rooted in nature, given how many "weird" sex stories and…
Whereas with the dolphin example, the point was for the dolphin to enjoy it. There was no "morally purer" point.