Lots of investors have probably been waiting for proof that burger lovers aren't losing their appetites over the mad cow controversy. Wendy's (NYSE:WEN) December same-store sales rose 9%, saying the headlines had little impact on sales. Could it be the consumer is blowing off any worries stemming from the unhinged Holstein?

It may be too soon to tell, considering that the mad cow news mooed onto the scene Dec. 23, and the data are for the month ended Dec. 28. That represents just five days of post-mad cow news, with a major holiday thrown in. Granted, Wendy's said that sales remained "strong" during that last week.

The high same-store sales don't come as too much of a surprise, considering the fact that McDonald's (NYSE:MCD), Wendy's, and private chain Burger King all stated in late December that consumers continued to queue up for their fare.

Fast-food chains were quick to disassociate themselves with the Washington meat plants that produced the guilty cow. (In fact, in today's press announcement, Wendy's stated it has had an existing policy in place not to accept meat from sick or "downer" cows -- a query both consumers and investors alike might ask, for some peace of mind.)

However, the mad cow disease story has been unfolding on a daily basis, with more and more details being revealed. As Fool Rex Moore pointed out yesterday, despite assurances, questions remain. If additional unpleasant news unfolds, the consumer's willingness to give fast, cheap burgers the benefit of the doubt may soon change.

For now, hamburger chains like Wendy's definitely have one thing on their side, besides the recent renewed American love affair with the hamburger -- so far, there's little sign of mass hysteria over this.

But what will January hold? With mad cow a late December development, January sales should really show investors whether the mad cow has run amok, if only in consumers' imaginations.

Are you still lining up for burgers, or has mad cow ruined your appetite for the classic entree? Talk it over on the Fool's discussion board dedicated to Wendy's, or set a place at the Food board to talk about mad cow's effect on the industry overall.

Alyce Lomax welcomes your feedback at alomax@fool.com.