The question of what we owe animals is not sentimental but philosophical: if suffering is genuinely bad, why is the animal's suffering an exception? Nasreddin never argued animal ethics directly, but his stories treat the donkey as a genuine character with genuine interests — which is already further than most formal philosophy has been willing to go. The moral circle has always been extended, eventually, to include those it once excluded; the question is only when.
Each step builds on the last.