To be precise, it is because the kitten is too young and does not have the ability to urinate on its own, so the mother cat needs to lick it to stimulate excretion. This will not happen when the kitten can excrete on its own. When the kitten is one month old, it can use the litter box to excrete under the guidance of the mother cat. The hard-working mother cat will also help the kitten bury the feces.