My husky has recently gotten pregnant and right after we brought her back home she has been very aggressive towards my other dog which is a chihuahua also female, to the point where they can be together because the husky will kill her.Before she was never aggressive and loved each other. What is causing my husky to be so aggressive?

- Hormones.

It's not unusual for any breed of animal to become hostile toward another female or male when they're pregnant. It's a protective behavior inherent in all animals because in the wild other females and sometimes males will try to kill newborns to eliminate competition within the pack. This behavior will likely continue for sometime until after the pups are born, perhaps up until they are weened. You have to remember the natural instincts in all animals and what is in the basic nature. Just keep them separated for a while. The pregnant one may settle down after a while but expect her to become very protective right around the time she is due and after the pups are born. Good Luck.