I need help!! I have two mini dachshunds. one is seven and the other one is five, both females. We have had both of them for about five years now and have never had any problems. The younger one has been acting very agressive to the other. For example bitting and causing roxy to bleed. This has happened several times in the past two weeks. We have tried to keep them apart by keeping the agressive one in her kennel. We can not figuer out why. Nothin has changed or is new in their environment.