Out for a ride today through some fields and as we were coming back through the second on my horse spooked.
I saw a walker and a dog...fine...not a problem, the Walker saw me. Horse is fine with dogs .
Next thing I know dog has bolted towards us barking and jumping up at my horses face.
Horse bolted a few meters then I managed to get him back under resonable control but he was freaking.
Walked has started calling dog but didn't particularly rush to come over until my horse started spinning.
By this point digs running circles, barking, taking no notice of owner or me.
This carries on for a few minutes....owner by this point obviously realizes that it's not a safe situation and tryst his hardens to catch his dog and flaps the lead around (not helpful but I appreciate the thought behind it)
He says to me 'can't you just gallop off' to which I reply surely your dog is going to chase?
My thoughts were try and keep control until the dog is caught. Surely if I let me horse bolt across a field a) it's dangerous for me and him and b) the dog has a very high chance of following in which case the owner has even less control and the we are back on a road...
Anyway....after a few minutes of palava I hear a thud....dog yelps and stops...my horse stops...owner goes to dog and the whack it one as well
the realizes that hes been kicked.
I hang around ask if he's OK where was he kicked....his front leg doesn't look good.
Owner tells me it's fine and to go...I say are you sure and he says yes which way are you going. I head off and get home in one piece but very shaken.
The thud is ingrained in my head 
I am assuming legally it's the dog owners fault but just wondered what I should do next? If anything?
I am also insanely proud of my horse. He's a ex racer and we have had our problems but I can't help being proud of him that he listened and really tried his hardest to hold it together and didn't bolt blindly home.
Horse is barefoot so no shoes but I know he got a good one in...the force of a horses kick on anything is a hard one.
I'm also a dog owner of a dog who has her moments but I never let her off I don't think I can't keep her under control and I am always on the lookout for 'triggers' so I can get her back before its a problem.