I work for a rescue organization and this is a common adjustment issue. Hope this link helps (it applies to all dogs, not just GS)

http://www.gsgsrescue.org/resources/about-german-shepherd/adjustment-period

of all my rescue dogs, only 1 or 2 ate from day 1. it's a big adjustment especially for a senior dog. at 9 years old, if he was owner surrendered, you can bet he's confused and wonders why his world has been turned upside down. if your stepmom is feeding kibble, have her try mixing in a little canned food to make it more tempting. a healthy dog won't starve itself so it isn't unusual for a dog in this situation to go 3 or 4 days without showing much interest in food.

good luck and God bless your stepmom for adopting a senior dog!!

You may wish to contact the Humane Society and ask what food he was eating when he was with them.

Agree with Nina that wet food is very tempting!

I agree with nanny, find out what they fed her. It could be that she just doesn't like the food she's being given. At our dog pound, they prefer Dog Chow because the dogs like it and it's consistent and they have less stomach issues if they stick with this same food.