I very seriously think they need to increase the karma given from killing a pet. I'm not proud of it but a couple months ago while soloing a bishop started battle healing mobs i was fighting. I barely survived and didn't have a pet out so i opted to just go back to town. About a week later i found him leveling his hatchling and killed it.. All i got was 300 karma which took maybe 10 minutes to work off.
Now once his pet had been killed i never bothered him again, actually i bought one of the nice pet rez scrolls so that next time it dies it won't be too bad. But if had wanted to i coudl kill pets pretty indiscrimanatly and the penalty is laughable. I think double or even tripple the penalty might be in order.
Edit: i had 10 pks at the time so definately a low penalty.
Remmember you will turn red, if you got more then 5 PK's you WILL drop if you die as you have karma, but no your PK coun't wont increse, But yeah whoever can openely attack you without flagging.