Fading kitten syndrome

Fading kitten syndrome (FKS) is a catch all term that is used to describe pre-weaned kittens that stop growing and gradually decline over a short period (usually hours to a few days). Although always a worry, birth defects are a relatively uncommon cause of fading kittens. FKS can affect individual kittens within a litter, part or the whole of the litter. FKS can be a one off event or be an ongoing problem in a breeding colony. 

In pedigree cats around 8.5% of kittens are stillborn and a similar percentage die before weaning. There is considerable variation between cat breeds with most of the common breeds showing pre-weaning mortality rates between 5 and 12%. Recent figures for domestic shorthair (DSH) cats are not available but limited information suggests that FKS is less common when compared to pedigree cats (although in shelter and rescue facilities death rates are higher at around one in eight kittens).