It's abnormal for a cat to not defecate for three days. This is likely due to decreased activity and reduced digestive motility, leading to constipation. Kittens typically defecate 2-3 times a day, while adult cats defecate 1-2 times a day.
What to do if your cat is constipated:
1. If the cat is still in good spirits, it means the situation is not very serious. Exercise and feeding probiotics can improve the symptoms. 
2. It is recommended to give your cat a suitable amount of honey water or food with high water content, while reducing the amount of high-protein food. This can help soften the stool and promote bowel movements. If the symptoms do not improve, you should take your cat to a veterinary hospital for enema treatment as soon as possible.
3. Adjust the diet. Stop feeding your cat dry, hard cat food. Feed it easily digestible foods such as fish soup, meat porridge, and fruit and vegetable puree to reduce the burden on its stomach and intestines.
4. If the above measures do not work, the owner should take the cat to a veterinary hospital in time and use an enema under the guidance of a veterinarian. After that, the owner should take good care of the cat.
