Continuity mistake: When Karen finds Terry's corpse, there is nothing visible on her, and half her body is shown. In the next shot a white blanket is suddenly on her body, all the way up to her neck. (01:03:15)
Continuity mistake: When Eddie is transforming into a wolf in front of Karen his left hand turns grey and grows hair down to the knuckles. Then in the shot of his arm muscles expanding, his left hand has a normal skin color and hair only down to his wrist. Apparently, while editing no one checked to see how his hand was already established. (02:09:55)
Answer: Whether it be dog or wolf, the primal instincts take over. Every creature, in nature, has an urge to seek out their own kind. When the husbands were bitten, they are consumed with the desire to hunt, kill and mate.