Hana attacked another dog in the park today. While she's shown a bullying streak towards certain dogs before, she's never been aggressive. Other dog got some puncture wounds, but should heal fine fine. (We've already offered to cover cost, etc).
The problem is that we now be definition have a reactive dog and I'm not sure that we are equipped to handle that...at least not with a dog that size. Likely outcome is that we return her to the breeder. We've already been in contact and they've been extremely supportive. At the breeder she will get the training and structure that she needs, something I'm not convinced that we can provide (And will potentially later get re-homed).
(edit): Now that things have calmed down a bit, we've spoken with eachother, spoken some more with the breeder and then finally with a trainer and are starting new classes on Saturday (and keeping her for the time being)
(edit2):
It turned out that it was somewhat provoked. Hana was playing with 1 dog, when a 3rd dog come up to them and started barking aggressively at them. As Hana is not one to back down, she responded in kind and adults intervened..it was then that she managed to get hold of the other dog.
Still we accepted that we did not have the necessary control and made several changes;
The breeder has always recommended to use prong collars. I've been resisting that, but in the light having a strong, dominant confident dog (and the alternative really being returning her), we went ahead and got one.
Other was talking to a trainer that also trains using those collars. She's one of the top obedience trainers in the country and we started attending her classes and the transformation has been amazing.
Her obedience (on leash) is pretty much perfect. Off-leash, she's still not to be trusted in familiar environments and will be a jerk, so most of her play is now on a checkcord. She gets relatively little play with other dogs, but that means that she turns her attention to us instead, which is a good thing.
Still not happy that we have to use a prong collar, but the results have must certainly been worth it.