Dog Injured In Household Fight

[Herman]

A friend has three miniature poodles. Two are older, neutered males from the same litter she raised from puppies. The third is an adult, spayed female who was adopted about a year ago. One of the males, increasingly aggressive toward his sibling for a couple years, was recently injured by the female when she defended the less aggressive male in a spat between the two males. Advice?!