First and foremost, let me express my sympathies to your entire family for the loss of an animal.
School counselors are wonderful resources for helping children/teens deal with loss. Often, high school counselors have special training in this area and know how to reach a teenager who is experiencing so many emotions in a short amount of time (disbelief, anger, sadness, etc.)
Please contact your school and see if the school counselor can make an appointment to talk with your daughter. She also may find a way to help her make this awful experience in to something with a positive ending, such as working in a shelter, becoming an advocate for animal safety, etc.
Good luck during this difficult time.
Louise Masin Sattler, NCSP
Nationally Certified School Psychologist
Oh - I am SO sorry for your loss. Losing a pet is always hard but witnessing such a violent event is especially awful. I think the important thing is to give your daughter lots of opportunities to talk about how she feels about this horrible situation. I think it's actually better that she's 16 (and not six for example) because she'll be better able to make sense of what happened. Young kids might develop a deep fear of dogs for example. But even at 16 it's not going to be easy and she'll likely be sad and upset for a long time - you all will!
I'd be especially aware of any feelings of guilt she may have. (If she accidentally let the cat out or if she was supposed to be watching the cat she may feel like the attack was "her fault". She may also feel like she should have done something to stop the attack once it started). I think it's important for you to do whatever you can to alleviate these feelings. She needs to understand that even though all the animals involved were domesticated pets, they're still animals and that's how nature works. It's also really important for her to know that she did exactly the right thing by staying out of the fight. Once dogs are in a frenzy like that they'll attack anything - she could have been seriously injured herself if she'd tried to intervene.
If you're open to getting another cat, you could start talking about that to her. Maybe not right away while she's still really mourning the loss of your old cat, but it might give her hope and help her move on to start thinking about a new cute little kitten in her life.
Again, I'm so sorry this happened and I'm sending your whole family my best thoughts.
I'm sure this was an awful sight to have to take in. I would say, however, that at 16 many young adults are able to process and understand this situation from a nature stand point. I would suggest that you first comfort her and then just ask if she wants to talk about it.
She might not yet, nor for a while, want to talk about it. If she says no then just ensure her that you understand how she is emotionally hurt and that you will be there for her if she does want to talk about it when and if she does. If she doesn't bring it up then just watch and see if how her mood is over then next few weeks. It happened yesterday so the wound is fresh... but if she doesn't talk to you she might use a friend or boyfriend to talk to about it. Don't worry this, at her age, will most likely have little to no lasting emotional affect on her. She will always remember it, but it wont change her in life.
So. Be there if she wants to talk and if she does want to talk then let her talk and explain what happened, what she saw, and let her talk about how she feels. IF she doesn't want to talk, observe and be mindful.
Sorry to hear about your cat. Pets are part of the family too.