My first thought when I found her under the bush & examined the damage was "I gotta finish her" (which would've been super hard to do but I'd rather put her out of her misery) then I saw this message board and read other "help! Dog attacked hen!"-threads... She definitely has an intense open wound and my second thought was to leave her there under bush -- again- Google To the rescue!... I opted to spray hydrogen peroxide from a spritz bottle and lay a clean washcloth upon the wound and finally -- okay! You better come inside since its cold and rainy- she's got an extra shirt layed over her back.. She's in a plastic tote bin.. And next to the chicks nursery (warm!) Sigh ... See pics below and LMk - I'll take to Vet early morn if u advise ..