Thanks to both of you for taking the time to answer my long-winded rant!
The strange thing is that this woman could not (under ordinary circumstances) have profited or benefited from our donations because they went to the shelter, not to her. One can of course imagine quite a far-fetched scenario whereby she was 'in cahoots' with the shelter and they solicited soft-hearted people's donations and then shared 'the loot', but that would be quite a scandal if it were ever found out! Besides, Occam's razor would suggest assuming (aha, assuming!) the simplest explanation (tentatively of course) in the absence of other indications, and a diabolical booty-sharing conspiracy between a shelter and a fake adopter would seem rather less plausible than a case of laziness overcoming compassion. (Not that Occam's razor makes us know for certain what happened: obviously there are situations where highly implausible things turn out to be true. That's why sometimes one gets in trouble and is accused of lying when telling the truth: it may not sound as plausible as a well-crafted lie). With the limited information available to me, I can only speculate that she did want the dog, but when it turned out that rescuing the poor creature would have required a greater effort than she had perhaps imagined, she simply couldn't be bothered to make that extra effort in the short time available. She cared more about her immediate comfort than about the survival of a distant creature whose suffering she couldn't witness first-hand. It wouldn't be the first time that a human has made such a choice.
I also got the impression that her belief in supernatural agency and the afterlife diminished her motivation for helping. If the dog is going to heaven anyway, why help it? Why help anyone, then? That's where her 'logic' seems to lead. Not, of course, that she was necessarily acting in accordance with rational or indeed ethical considerations. She had an impulse to save the wittle fwuffy puppy, then it was too hard and she gave up, and then she rationalised it by muttering about heaven. So it seems to me. And in so doing she was perhaps paying insufficient attention to her role model, Jesus, who is instead portrayed as prioritising the welfare of others over his own. This is an aspect of what I interpreted as her hypocrisy in this case.
As for gullibility, again, one can only go by what limited information one has. In this case, there was the added pressure of urgency: time was so short that I didn't have the luxury to ruminate about various possibilities regarding this person's motives and likely behaviour. I could either do nothing and potentially deprive the poor creature of what was perhaps its only lifeline, or do something, perhaps providing it with its only chance to survive, but maybe fail and be incredibly disillusioned, angry and hurt. I chose the second, I was betrayed, and I did end up disillusioned, angry and hurt, which of course pales in comparison with what the dog paid for the failure of this effort. However, I still think that given the conditions under which I was operating, I made the ethical choice. I chose to help rather than not to help; and unlike the sanctimonious 'adopter', I prioritised another, distant creature's welfare over my own comfort. I acted on the assumption that this woman's emphatic and numerous protestations of commitment were genuine, given that I could not know for sure whether they were in fact genuine.
I'm always surprised, it's true, when I discover that someone was lying to me all along (though 'lying' probably isn't what happened here). Maybe it's because my expectations reflect my experiences of life so far. Of the large number of interactions with other humans that I've had over the years, most have not (at least, to my knowledge) involved lying. Lying is therefore an anomaly to me and it never fails to catch me off guard. It never fails to make me feel as if the ground had suddenly disintegrated, leaving me standing on thin air. It never fails to make me feel like a fool. I do go into things assuming honesty from the other party. Is it game theory? Is it an evolutionarily advantageous mechanism developed over aeons of interaction among humans and other primates before them? Is it the result of an empirical tendency to assume that if something usually happens (e.g. honesty) it will again mostly happen? Is it wishful thinking? Whatever it is, it can also be characterised as gullibility, insufficient cynicism, optimism, or many other things good or bad. Well, at least I'm analysing it to death, which can't be bad, right?
And of course I won't compromise my morality because of this highly unfortunate incident. I won't shy away from attempting to save other lives; I won't make this person's laziness, hypocrisy and betrayal hurt other beings that may need my help.
Any additional suggestions, meditations or other contributions will be appreciated and will be answered - maybe not immediately, but whenever a window of time appears.
Thanks again to you all - Ants.