This is an interesting ethics exercise. I'm sure that in today's dominant view of humanity vs nature relationship, few will see any dilemma in this question.

For most a human life is far more important than any amount of lives of other species. The interesting exercise in this conundrum is to question, why is it that we feel this way? What makes a human being's life worth more than any amount of other beings? Why do we feel superior? Are we worth more because we're more self-aware or more conscious (if we can prove scientifically that this is actually true of course)? Maybe being anthropocentric is simply a hard-wired survival instinct of self-preservation of the species? I know that if I had to choose between the life of a close one and the life of an animal I'd of course choose the human animal.

The truth of the matter is that this particular example is an extreme and rare situation, which covers a tiny percentage of all animal suffering and which in reality it's not something that (fortunately) many of us have to worry about. And as all extreme and rare cases, perhaps it should be treated as the exception.

On the other hand, if we're going to have an honestly concerned evaluation of animal rights, would it not make sense that we start with the primary source of suffering? You know, the subjugation, farming and slaughtering of millions of beings, for meat, furs, leathers, cosmetics, all of which are no longer necessary for the survival of 21st century Homo-sapiens (or "wise" man).

There are plenty of lifestyle choices that we make on a daily basis, which may or may not contribute to very real animal suffering going on right now. To name a few, what I eat, what I wear, what entertainment I choose, are simple decisions which everyone can make based on individual ethical awareness and concern.

If we tackle the easier ethics problem first - justifying the main source of animal abuse as a means for human comfort and pleasure - perhaps we'll be better equipped to deal with the exceptions of animal abuse, such as the one of when a human life depends on it.