Are people allowed to murder pets and monkeys for no reason?

For example, playing as hammy, everyone considers hammy to be KoS. Why is this allowed? If this is allowed, surely that means hammy is an antag role, therefore it can also be an asshole and hurt others for no reason?

What about monkeys? Is it allowed for them to be killed for no reason? Why can’t monkeys be assholes aswell? 

As an Animal

https://forum.spacestation14.com/index.php?/topic/2213-antag-status-of-animals/&do=embed

 

As a Person

https://forum.spacestation14.com/index.php?/topic/2214-self-antagging-against-animals/&do=embed

 

Escalation

https://forum.spacestation14.com/index.php?/topic/2215-escalation-rules-when-animals-are-involved/&do=embed