Oh that is so it, Palefrost, Sarah- I'm changing my custom user title.
On a more serious note, you'll see I don't debate anything regarding economics, coz I completely suck at that. So I can't debate everything 
Todd: I presume in the final sentence you're talking about having an actual physical/sexual relationship there. Your response is the natural response to what I wrote and it is a very valid concern. My conclusion was basically that consent is most definitely a relevant issue, and I was essentially attempting to illuminate how one should go about it. Oh yes, and I wasn't saying that people actually claimed toddlers to be the same as animals...rather it's a convenient analogy but often people forget that it's an analogy and go on to use it as a basis of argument, which is improper.
Your cautionary line "(not necessarilly meaning one is better per say or worse but just differences in understanding as well as make-up)" is indeed reflective of this uncomfortable awareness that often humans are valued on this kind of pedestal that marks them out as intrinsically superior to other animals. I would assert that many detractors to the notion of being able to have any meaningful relationship with another animal are likely to hold this, especially if they aren't objecting for reasons of consent. It's quite funny, actually. On one hand some people might say "it's unnatural because they're a lower form of being", and other people might say "it's not right because it's manipulating and taking advantage of them". Anyway.
So to continue on, or rather, to paraphrase, what we're pondering is the issue of interpretation of reciprocity. To railroad this onto a more specific track that I vaguely alluded to last post, an animal lover (or more specifically zoophile, if I may) might claim that "I love this animal, and the animal loves me back". What is at stake here is the validity of the person having affections for the animal, and what is being claimed is that both of them have a mutual understanding of the nature of the relationship. Throw in the sexual element and you have a molotov cocktail of controversy. What is at doubt, is the veracity of the claim that the animal values the relationship in the same way as the person does. It's not difficult to posit that said zoophile is being delusional in the same way that I noted in the previous post- 'allowing' the human to engage in sexual intercourse could very well be a case of simple positive reinforcement conditioning training (i.e. you let me do this to/with you, you get food in return). However this too is difficult to verify.
I would also cast some doubt as to how much import this claim has outside of pointing out misconceptions/deliberate belief on the part of the person. After all, the same issue can easily be applied to people-people interactions, as subjectivity at the very least implies that each person has their own distinct set of values applied in a distinct manner. More importantly, I think what really underpins what is at stake here is a fundamental moral method of judgment that you've alluded to- acting in the interests of self or of others. Back to the example- what people may claim is that a person who 'uses' their 'pet' for sexual gratification is being selfish, and this is justified because the they judge that the pet does not value the act in the same way. Thus it seems that the only way to avoid this charge is to demonstrate how this coupling demonstrates a mutual relationship of sorts.
This is obviously a very tricky and complex problem to tackle, and judgment is best left to, as usual, a case by case basis. There are examples of what could easily be described as a mutual and successful interspecies relationship (such as the man-mare couple Egon and Elksa- unfortunately I believe that the relevant article is no longer indexed), but there are also many many examples of related examples of animal abuse and maltreatment. The physical difficulties are also quite an important consideration in terms of health (there have also been cases of human fatalities due to attempts to copulate with stallions...which is a highly risky and generally not recommended practice), but I would be careful to note that this in itself does not have moral implications regarding the actual act of sex, but rather on the hazard to health. As in "you're taking/causing the risk, so you are obliged to consider this in making a decision".
