Thank you all for your responses . Both dogs are rescue dogs . One dog Klondike is longer with us about 3 years and is always a outsite dog . We did try him insite when we got him , but he will chase all the cats and try to catch them . He also is a bad marker , every wall and corner in the house he marks .Klondike is not neuter yet , but will be in the next few weeks . We had to much vet bills , thats why he is not fixed .Over the day he stay in the back yard and in the night we got him a doghouse in the carport chained on a leash . But he was befor a outsite dog and was already grown when we got him . The other dog Toby , we rescue last year . Toby just got neuter last Friday . He is a great insite dog and love cats . When we got Toby both dogs were ok the first 3 days . Then what I think happen they got jelous (sp) at each other and started fighting . Since that time we keep them all the time separated . That was the 4st time they were fighting . We all play with both dogs and walk with them and try to treat them the same way , of course one is insite and the other outsite thats the only difference .MA , nobody in our house is trying to provoke them to fight . We all , my husband , son and I love each one of the dogs . We all do get very absad when something like that happens .Our yard is fenced in . Next door are 2 dogs and Klondike is constandly barking at them , that only started a few month ago when they got a Roweiler puppy girl and Klondike don't like her . Klondike don't like any dogs who is biger then him and has no problem with smaller dogs . Thats funny , I wonder why . I sure will keep them separated again if you all think they may fight again . I was hoping that after today it would be over .The last time we separate them my husband got bit by mistake and the fight befor I got bit by one of them . Thats why we said let them fight it out , maybe they will settle after they fight it out . They stop fighting by themself today and Toby was the looser , but he was kind of hiding from klondike . So you all think they would fight again ???