"It is rather unfair, the reputation that the wolf possesses in Ferelden. For a people that so clearly adore their hounds, Fereldans simultaneously harbor a distrust of wolves that borders on the unreasonable. Unreasonable, that is, if one were not familiar with the ancient legends regarding werewolves. There was a time in Ferelden's past when demons inhabited the bodies of wolves in great numbers, causing the wars against werewolves and spreading great fear and panic. The werewolves were slain, but even today the noble wolf is still looked upon with distrust.
--From Legends of Ferelden, by Mother Ailis of Denerim, 9:10 Dragon.
An attack by wolves upon civilized folk happens rarely, often only in times of desperation and even then only when the wolves have the advantage of numbers. This can change during a Blight. When darkspawn rise onto the surface their presence dramatically alters the savage nature of normal beasts.
In Blights past, as the corruption of the darkspawn spread through the wilder areas of Thedasm it would infect the animals found there... and the more powerful of them would survive and be transformed into a more vicious and dangerous beast. A blight wolf is one such example, mad with the pain of its infection, and only through the overriding command of the darkspawn does it still retain some semblance of its pack instincts. Blight wolves are always found in large groups and will tend to overwhelm a single target if they can, using their numbers to their advantage. It is fortunate that these creatures rarely survive their corruption for very long.