A passage from "Espresso Tales" by Alexander McCall Smith, the second of the 44 Scotland Street series, page 233:

Cyril was a good dog. Although he liked to drink beer in the Cumberland Bar and to wink at girls, he had few other vices, and in particular he was not aggressive. He liked people, in general, and was always happy to lick any hand which was extended to him in friendship. If people insisted on throwing sticks, Cyril would always fetch them, although he found this tedious and pointless. But he liked to oblige, and he knew that it was obliging to do the things that people expected dogs to do.

But there was something about Matthew's ankles that was just absurdly tempting. They were not fat ankles, they were average ankles. Nor were they any different in colour from most of the other ankles that dogs usually saw. In smell, they were neutral, and so there was no olfactory clue to their attractiveness. It's just that they were immensely attractive to a dog, and at that moment Cyril could think of nothing else that he would prefer to do than to bite them.

But he could not. He knew the consequences of succumbing to the temptation. There would be the most awful row and he would be beaten by his father, as he thought of Angus [his owner]. There would be raised voices and words that frightened him. And worst of all there would be disgrace, and a feeling that the human world did not want him to be part of it. There would be rejection and exclusion in the most unambiguous sense.

Suddenly, Cyril stood up. He turned away from Matthew's ankles--put them beyond temptation--and began to howl. He lifted his head in the air and howled, pouring into the sound all the sadness of his world and of the canine condition. It was a howl of such regret and sorrow as to melt ilka heart, ilka heart.

And none of those present knew why he cried.