If the mouse is not afraid of cats - she is infected by a parasite Bashny.Net

Toxoplasma - amazingly simple, a habitat which may be any warm-blooded animal. Toxoplasma in cats prefer to live, because the body of cats - the most favorable environment for their reproduction.

To get to the house as any cat, Toxoplasma can manipulate the behavior of mice and other animals infected by it. For example, rats and mice completely cease to be afraid of the smell of cat urine, and even begin to feel attracted to her sexually akin. To end the cycle of Toxoplasma carrier must be eaten by the cat. However, the way in which the parasite causes the mouse to throw the cat's jaws are not fully known, and is now under investigation for the purpose of shedding light on this issue.

via factroom.ru