Dog in heat aggression

Question
Dog name: Isis            Age: 2 years
Breed: Husky/Rott mix     Sex: Female
Owned for: 2 years (the previous owners were going to drop her off at the pound before she had even finished breast feeding so we bottle fed her)

Isis, is normally a very loving yet cowardly dog. She is a bit energetic though and a bit excitable. She has been around cats, small dogs, big dogs, and adults and children and has never had a problem even when we are not around. But the other day a small (male dog) got through our fence when she was out there. She had just stopped bleeding from her vulva a little over a week ago. Something happened and Isis bit the dog she actually took some of the flesh off and the dog received some wounds (no muscle damage). She has never had a problem like this before or shown any signs of aggression. I am positive she wasn't trying to kill the little dog because (she is about 70lbs and the dog was 22lbs) if she wanted to she probably would have. and she stopped before anyone got outside.
What I would like to know was this a territorial thing?; a her being in heat thing?; or what would cause her to do this? She is not showing signs of aggression after it happened either. She also seems to be really depressed after it happened she hasn't really eaten and she just wants to stay in her kennel. I would really like some advice on what to do with her. Sorry if I seem a bit out of sorts it has been a long week. And she really hasn't shown any signs of aggression. She usually runs away and hides if another dog wants to fight. Any advice would be so helpful thank you.  

Answer
Dear Crystal,
Thanks for the question. Without anyone actually seeing the incident, it's tough to guess why your girl got into a fight.

Has Isis ever been around the other dog before?

I wouldn't worry about one incident. For all we know the smaller dog attacked her. Fix the fence and try to engage Isis in activities.  Take her for walks, play ball, et cetera. Get a food dispensing toy, like a Kong and fill it with treats and her regular dog food.

Nobody is sure what is happening or why - but many people report that their dogs enter into a sort of remorseful period immediately after some aggressive incidents. The dogs' outward behaviors are akin to that of an ill dog but in fact the dogs are healthy. The period usually passes within a few minutes, hours or days.

Happy Training!
AT