The experimental film The Private Life of a Cat by Czechoslovakian-born filmmaker Alexander Hammid and Ukrainian-born filmmaker Maya Deren was produced in 1944. There's no sound. It follows a cat giving birth to a litter of kittens and raising them to weaning age. The father participates, too, and even teaches them how to climb! And just to ease your mind, cat sex is implied, but not shown. (via Boing Boing)
Rest in peace, you sweet cat.