i'm sorry this happened but (imho) you were wrong to leave them out together unsupervised. even leaving dogs who are well known to get along with each other outdoors alone when you're gone to work is opening yourself up for lots of possible problems. back to what you can DO about this...you gate, crate, and rotate for the rest of the time you have these dogs, because especially if they are bitches, once they've gone after each other you can never be totally SURE that they won't do it again. you surely can NEVER, EVER leave them alone together, and if they're together when you're there you must watch them diligently and always have a clear plan for how you will separate them, should they get into it again. bitch fights are the worst. and greyhounds are no match for a sheppie, unless they can run. you can do the gate, crate and rotate thing, if you love all your dogs and you don't want to rehome any of them and you don't ever want this to happen again...you're gonna have to totally manage the environment. i'm sure there will be alot of training advice as well, but having had this happen myself, and living the GC&R life for YEARS now, i can tell you with pretty much 100% certainty, things will never be entirely safe for your dogs (no matter what kind of training you do), if you don't gate, crate & rotate. good luck!
mom to seraphina blue & the cashman
miss jeni-take-a-ride, rescued 7/07
shangri la's great white caesar, rescued 4/09
hearthside's cinderfella (RIP 4/20/09)
shep von bellefontaine (RIP 6/9/10)
voodoo lily (dsh) & cricket (african grey~RIP 7/13)