Summons?
Nope.
No, no summons are allowed unless it was given as a DR. HOWEVER...you can have a pet or get a friend to play as your animal pal. Your friendo won't be able to gain pp or buy things since that is only for Inuzuka companions or Summons.
So, if you just want an animal friend to hang out with and they're ok with not gaining any points and just being there for the roleplay then it's just fine. Make sure to gm-help about it to get icon change so you can send icon file to an admin.
It's a big risk to just have a pet, but that's what also makes for good roleplay since you will have to protect your animal from harm aswell as yourself.