I was wondering why my 2 female dogs are fighting really bad lately.The one had puncture wounds in her chest.?

Okay I have an American Eskimo and a Australian Cattle dog and lately they have been fighting like you would not believe.These are blood matches.The American Eskimo would never fight back and now she is and it's getting pretty bad.One is fixed the other is not.I went to get her fixed and she went into heat at the time.The vet said wait at least 2 to 3 months and then make another appointment.So now I am thinking that she is in heat again but I have read that they only go into heat twice a year.The cattle dog starts it all the time.I give all of them the same amount of love so I do not what is going on here.Although the cattle dog has always had other dog aggressions.She loves people but not dogs.When I got her I had 2 dogs and they never fought.They were males.I do also have another dog who is a male 8 months old.Any answers?