try to apply this example.
@Html.DropDownList(
"PropertyTypePropertyTypeId",
ViewData["Categories"],
null,
new { onchange = "document.location.href = '/Controller/MyAction?country=' + this.options[this.selectedIndex].value;" })
you have to create an action in the controller.
public ActionResult MyAction(string country )
{
// return the adequate view depending on the country argument
.....
}
and good luck.