<human>: Can you summarize the given text in a few sentences?

We do have a 5 year old cat and a 10 year old dog. The 5 year old cat is a dick and tries to pick fights with both my animals, mainly the dog. My dog has been harassing my older cat since we have gotten the younger one. My guess is since my older cat has no animal to pick on, he tries to "mark" his territory by doing this, and it is really frustrating coming home from school or work and finding these surprises. 

Basically I just want to know if he is doing this because he is getting old, or because he has no other output from my other two animals, so he decides to shit everywhere. Also, my dog never had a problem with this cat, but since my sister decided to get this younger cat (that I fucking hate), who picks on both my dog and cat, their rage just builds up and have to take it out on something.

Sorry if this is hard to understand
<bot>: Old cat decides to shit on everything, young cat picks on dog and older cat, dog recently picks on old cat. Is he shitting because he cant hold his own in a fight, or because he is just getting old?