I know Star saw the kitten yesterday as a squeaky toy and it got out of hand, he didn't know any better, but he has become more and more aggressive towards small creatures. He used to live with cats and did just fine, didn't bother them. The last year has been an entirely different story. He killed a stray cat this summer with Penelope outside, no mutilation to the body, just attacked until it stopped moving and then left it. Same with the kitten last yesterday. He continuously tries to kill the neighbors cat, he has started chasing the other neighbors chihuahua, he chases birds and squirrels. This is all new behavior.
In the last 6 months or so he has also started becoming more territorial and aggressive as well. He has started marking his territory, urinating over other dogs, kicking his feet after pooping, hiking his leg (he used to fall over or never hike it all all, maybe once in a blue moon. He also charges out of the house barking ferociously and "patrols" the yard barking. If he were younger or intact, I wouldn't be questioning this as much, but he's a 5 yr old castrated boy. He was castrated at 6 months old, I hated to do it so young, but he was being a jerk then, trying to dominate all the dogs in the house. After he was neutered, it stopped completely until now.
What can I do to try to restore peace in the house? I do make him sit and wait before going outside. He's also being extremely disobedient.