2 damage and 20|25% for poison (it is intended to be a bonus only)? Perhaps +1 cost?
I still think the % chance on poison could be a little higher. Dropping the direct damage is definitely a good idea though. That will keep it from outshining owl's eye. This is an important point because owl's eye is implicit balanced by the fact that you can only wield 1 at a time unless you pack additional cards (e.g. crusader or AW).
If you do go with 20 to 25% it could be interesting to have that just be a passive that applies to anything this creature damages (e.g. players and GP'd creatures).
This would help with the thematics a bit as well since anything the dog bites would get affected, not just creatures.