His place was taken by Josh Magennis while Paul Quinn came in for Adam Matthews in the only other change.
City made a great start when they took the lead in the ninth minute.
Chris Burke was fouled on the right by Joe Martin and when Peter Whittingham swung in the free-kick, Hudson rose high to head into the net.
Adam fired a free-kick midway through the half which David Marshall had to go full-length to save, but the Bluebirds stormed straight back and Magennis crashed an effort against the crossbar from a Ross McCormack centre.
The visitors were on level terms in the first minute of the second half when neat build-up play cut the home defence to ribbons and left Adam with the simple task of slotting past Marshall.
Cardiff were now looking second best and Adam fired in a free-kick that Marshall was forced to tip over, before Ben Burgess went close with a header.
In an isolated attack on the hour, Matthews rapped the post but the Bluebirds looked a disjointed outfit finding it hard to keep hold of the ball.
Michael Chopra replaced McCormack in the 74th minute but the home side never looked like claiming a victory.