In To Kill a Mockingbird, Chapter 10, what's significant about there being a mad dog in February rather than August?
"I thought mad dogs foamed at the mouth, galloped, leaped and lunged at throats, and I thought they did it in August. Had Tim Johnson behaved thus, I would have been less frightened." - Scout
I know the dog symbolizes racism, but why is she afraid that the dog had rabies in February but she wouldn't be afraid in August?
First, you are right about the mad dog being symbolic of racism. The dog is given a first and last name (instead of Rex or Fido) to further symbolize the dog's humanity. Atticus is reluctant to kill the dog, and he literally hates the idea of killing any living being. But, like a sheriff walking down an old Western street about to defend his town from a murderous gunslinger, Atticus forces himself to do his duty. Symbolically, the dog also represents Tom Robinson, and it has been infected with a disease of which he has no control; likewise, Tom has been accused of a crime he did not commit and over which he also has no control over the events that will follow. I think the mad dog appearing in February instead of during the hot summer months (when rabies is most often transmitted) symbolizes how racism is constant and not restricted to certain times or places. The fact that the dog does not appear in great distress--like mad dogs who "foamed at the mouth, galloped, leaped and lunged at throats"--also shows that racism can exist in many forms.
This is an interesting question. Chapter ten clearly implies that it was odd that a dog was rabid in February. Calpurnia says:
“I know it’s February, Miss Eula May, but I know a mad dog when I see one. Please ma’am hurry!”
The significance of this is twofold. First, part of the deeper symbolism of the mad dog is that it is out of place. So, this fact alone causes an ominous tone. In other words, when things are out of place, it creates a setting which is unsettling, such as when there is a snowfall in Maycomb or when Miss Maudie's house burns down.
Second, because the dog represents the unruly / bestial side of humanity with its intolerance and racism, the appearance of the dog shows that there must be someone in whatever season to stop it. It is interesting that Tate, the sheriff, does not take the shot. Atticus takes the shot. We actually find out he is the best marksman in the town. This makes sense, because he is also the one who protects the town from racism and protects "mockingbirds." What makes all of this even more powerful by way of contrast is that the chapter opens with these words:
"Atticus was feeble: he was nearly fifty."
Atticus, though feeble in the eyes of his children, is the strength of Maycomb.