Why Do Cats Hiss At Their Kittens. They also eat the kitten if they feel threatened. That’s why cats use hissing sounds to warn the “opponent” or “threat” to back off.
A mother cat will hiss at her kids to warn them of impending danger. Why do cats hiss at new kittens? This can be true even of very sociable cats during gentle interactions.
Now, that's not to say that a mother cat will not hurt her kittens.
According to koski, “mother cats will hiss if someone comes too close to their kittens,” whether it’s a person or other animal. When the kittens were about 4 months old the mother started to be more aggressive towards them and now if she sees one within a few metres she will spit, hiss, growl and yowl angrily at it and even attack it. She isn't abusing her kittens: Even if your cat is the sweetest little cat on the planet, if she has ever felt threatened or needed to send a warning to someone (feline, canine or human), she has probably hissed at some point.