The four key signs of fading kitten syndrome are:
1. Low  Body Temperature (<99F or <37.2C). Affected kittens feel cold to the touch.
2. Lethargy. Fading kittens may be unresponsive, do not move around like healthy kittens, and cannot stand up properly.
3. Vocalizing. Fading kittens may vocalise abnormally, crying or mewing in an unusual way.
4. Difficulty breathing. Fading kittens may make exaggerated breathing movements, or they may gasp.