two kittens fighting

Question
I recently adopted two kittens, I adopted the first one a week before the other, so they are not from the same liter. the first kitten is 13 weeks old and the second is 9 weeks old. They are both very playful, but the 13 week old is really rough with the younger one. He attacks him till he cries, and will even attack him while hes sleeping. I can tell that my older cat is enjoying it because he makes this happy little noise as he runs across the room, but the little one is hissing at him. What should I do since the little one is too little to really fight with him,and can't stick up for him self?

Answer
Lauren,

The play that you are seeing is perfectly normal between kittens of similar ages. It may have been a better idea to have adopted kittens of the litter, but the fact that they are from different litters really isn't too big of a deal. There may be a bit of bullying going on as I am not sure that you have properly introduced them. The proper way to introduce a new kitten or cat is to isolate them for 2-3 weeks behind a closed door. This has a few purposes. It serves as a quarantine period in case either cat has a bacterial or viral infection incubating. It also allows the cats or kittens to get used to each other's scents and sounds which means that introductions tend to go more smoothly. Just because your new kitty is in isolation doesn't mean that you shouldn't take equal time to spend with the two kitties and play with them. You will actually learn more about what is normal play, eating, drinking and eliminating behavior for your new kitten which is important to be aware of in case he becomes ill. With proper introductions and lots of treats and play the kittens should become the best of friends. It is important to remember that no matter how young the kitten is they are still territorial and not terribly fond of change so it is important that any changes in their environment or company be made gradually. I would recommend that you also be sure to have one litter box per kitten per level of your home to prevent any unwanted accidents. Food and water must not be kept too close to the litter box as cats don't typically eat where their toilet is. The litter should be cleaned at least once a day to prevent odor or behavioral issues. It is wise to be sure that you have a few sets of food dishes for the kittens because if there are issues with bullying the food dishes can't all be guarded by the aggressor if they are in different rooms. I hope that you have found this information helpful. If you have any further questions or concerns, please don't hesitate to contact me again.