40-day-old kittens usually have the ability to defecate on their own. Generally speaking, kittens can learn how to go to the toilet with their mother cats from birth. However, due to different cats’ learning abilities, the time it takes for a cat to go to the toilet alone will also vary. Some kittens may need guidance and help from their owners, but they can usually learn quickly if given proper guidance.

However, it is worth noting that if the kitten has difficulty or abnormal defecation, such as frequent Incontinence, defecation in inappropriate places, etc. can be caused by factors such as physical issues, emotional stress, genetics and breed, litter issues, or social issues. In this case, it is recommended to consult a veterinarian promptly for appropriate examination and treatment.