Kittens that are a month old usually start learning to defecate on their own, but they may not yet have full control over urination and defecation, so they may need manual assistance and training. Mother cats usually help their kittens defecate by licking their anus. If kittens don't have their mother's help, owners need to gently stimulate their anus with wet wipes or similar methods to help them defecate.
As kittens grow, they will gradually learn to control their urination and defecation and will begin using a litter box. If you find that your kitten has not defecated for an extended period of time, you may need to seek help from a veterinarian.
