agressive Hot dog...HELP

[johnism]

Ok back ground first off...
3 dogs(Male Collie/lab mix(10 months) ,Female Boxer/mastiff mix ( 6 months ),Female Daschound (3 years )) and two cats ( 15 years old ).
We had to put down two dogs last year one 15 one 17 .
The two younger dogs play and get along and share food. The Dash tried two attach the collie but he put her in her place awhile go so she stopped ( he was here before the mastiff ). Now the mastiff she will just attack and she now chases the cats really bad . The mastiff and her have fought and she always starts its. Last night the mastiff was sitting there and she just attacked her then the mastiff fought back and beat her up pretty bad ( eye pooped out ..she is fine ). So does any one have any ideas of what I could do to tame her aggression against the mastiff / cats?
Thanks for any help / input ,
John