So, I’m reading this as she’s biting down once and causing serious damage to the bone. To be quite honest, if she’s causing that kind of damage with just one chomp, I don’t know that there’s anything truly safe to give her. If she’s gnawing on it and causing this sort of damage over time, there are MUCH better options to give her.
I would not buy Nylabones, as they are not edible and the plastic should not be ingested. I would, instead, look for more natural options. Antlers, marrow bones are both decent options, just be vigilant in checking teeth for cracks or splinters. I would also look into softer (but hard to break) options, like West Paw Zogoflex toys.
Have you talked with the trainer about things you can do to curb the anxiety? Because you have a herding breed, your dog needs daily mental work…this means more than just basic obedience. I would seriously consider looking into a sport of some sort. Sports and higher level obedience will actually calm your dog and help build confidence.
Editing to add…I’m told Goughnuts are a good option for power chewers. http://shop.goughnuts.com/product.sc;jsessionid=F9EC4BDBFB4633B0976DB7A914B6E1C6.m1plqscsfapp04?productId=10&categoryId=1
I think that any dog that is with a loving human will adapt to its living situation. The only thing is that it seems like it will be alone for long periods of the day., and it isn’t your house. Have you spoken to the family that you are living with about this and gotten their approval? Perhaps you can find a way to spend more time with it, or bring it with you or maybe the family that you are with can provide companionship when you are not around? Another nice option if you don’t currently have the means or enough time to devote to a pet full time, would be to volunteer at a local shelter. My friends an I did this in college aswe were not allowed to have pets, and I have to say it was quite fulfilling and we helped an awful lot of animals.
I would not keep a dog in that particular situation unless your family agrees to take care of him when you aren’t there. Maybe a cat is a better option? Or simply waiting until you aren’t in school with a crazy schedule, instead. Think of the animal’s needs, not your desires.