Why is my 9-week-old kitten sleeping in the litter box and aggressive?

Yes he could be teething. This behavior is common in young kittens. Please keep him in a safe place where he can’t chew on electric cords. He should be less bitey as he grows up. Make sure you play with him with a laser light or toy on a string so your hands aren’t available to bite. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Salam.

Aggression is usually associated with negative behaviors such as hissing, growling, swatting, etc. What you are describing sounds more like normal kitten playfulness, if Bella is just pouncing, nipping, or hopping around. Keeping her out of your room if she is too excitable can help keep her form hopping on you when you are trying to sleep. A pheromone diffuser such as Comfort Zone can also help her to relax and settle down some. Making sure she has plenty of toys to play with, including things you can safely play with together such as a feather on a stick or a laser pointer can help get out some of that energy without having her bite you or scratch your hands. If she becomes too excited, getting up and walking away/ignoring her until she has calmed down again can help teach her that the fun ends when she gets too excited. If she is calm and quiet, rewarding her with a treat, a play session or some attention can help teach her that's the behavior you like. If she is actually showing aggression, IE biting hard, hissing, ears pinned, low growling, swatting, etc, then I would highly recommend seeking out a trainer or behaviorist in person to address the issue and try to find the cause such as stress or fear.

Laying in the litter box is not uncommon for a cat that just moved to a new home, many cats tend to do that, they tend to feel "safer" in the box. if he does not seem to have any problem urinating, if he is eating and drinking normally, just give him some time to open up, he will grow out of it.

Sudden aggression and behavioral changes in cats can indicate pain or illness, so if you haven't already, a veterinary check up is best. If your cat checks out healthy, it may be there is a lot of stress causing your cat's behavioral issues. Making sure she has her own access to food, water, toys, treats, hiding spots etc from other pets or people is best. She is also still very young, and may just have a lot of energy/is still learning what appropriate behavior is. Ignoring bad behavior, increasing play and activity times, and rewarding calm, quiet behavior is best to teach her the right way to interact and to get out that excess energy. If the behavior continues even with this, speaking with a veterinary behaviorist is the best next step.

Locking her in a dark and confined room may in fact be worsening the aggression. Behavioral therapies such as Feliway pheromone plug -ins/sprays, VetriScience liquid composure supplement daily (both available online without a prescription) and having her spayed may help as well. Other options include prescription anti-anxiety/anti-depressants which would require a consult/exam at your vet’s. Good luck!

Unfortunately there is not a lot you can do to discourage this bevahiour. Anything that you do to try and make it an unfriendly sleep environment would also make the litter box feel unsafe to do her business in. I would recommend making sure your kitty has a couple of nice comfy spots where she CAN sleep peacefully, and encourage her to use those areas rather than the litter box. You can gently pick her up from the litter box and place her in an alternate location, using products like catnip and Feliway in the alternate areas can help too.

Unfortunately, kittens that were bottle fed can be aggressive and not as friendly. You can try to put some feliway diffusers in the House and spray her sleeping areas. Feliway is a cat pheromone which can sometimes help to calm them. Also, give her more time. She has been moved from multiple house in her short life and now around new cats (they don’t usually remember family). This can be stressful and can take weeks for them to acclimate to. I hope this helps and she starts to get use to her new living conditions.