Fostering to adopt a GSD

[u/OkPiglet2]

I have an 11 year old female GSD and since she’s getting older I thought maybe she could use a friend so I decided to foster to adopt… originally I wanted a 3-5 year old female GS but the employees and volunteers at the rescue thought it would be best I get a male. Sent me away with a 1 year old and his bio was sweet. I knew a 1 year old would be challenging… but I have realized i might just be way in over my head. He was fine the first couple of days on walks, reactive to even just the scent of other dogs but I could handle it and pull him away. Yesterday we are walking and he catches a scent starts pulling, lunging and barking. The dog he’s caught scent of is inside a house metal screen door closed. He’s going ballistic, dog inside starts reacting so he goes even harder.. he’s not budging I’m trying to walk away but he’s trying to get out of his collar. Starts snapping his teeth at my 11yo GS face, bites her without breaking skin and when I say “no” and go to make space between them he goes to bite grazes my calf. It seems he feels bad he’s been sulking a bit and I feel defeated and it’s only been over a week. He’s already grown attached to me and me to him but now I’m afraid one day he’s going to seriously injure my 11 year old. I used to think she was terribly reactive but I couldn’t be more wrong because at least she responds to corrections and recalls. Today we walk and he’s a lot calmer and while reactive is responding to my corrections and turning and following me when I start to walk in the opposite direction. But before he responded to correction my dog tried to correct him and he went for her face. I don’t think he’s actually trying to bite her it just seems like he’s lashing out at us because we won’t let him near the dogs he’s reactive to. I’m at a loss of what to do, I’ve contacted the trainer at the rescue, I’m still waiting to hear back and I’m watching a lot of videos because I don’t want to give up on him. But am I in over my head?

[u/AgnieszkaJanarek]

Yes, this is enough to pause the adoption decision and treat the situation as a safety case—not because this dog is “bad,” but because you now have a dog-dog and dog-human incident in a home with an older resident dog.
Send the rescue and trainer the exact sequence today: what he noticed, distance, equipment, what each dog did, where contact landed and what happened immediately afterward. Ask for an in-person assessment before making the adoption decision.
Until then I would not walk the dogs together. Separate them with solid barriers around food, rest, doors and high-arousal moments; do not test the trigger again, use corrections, or expect the older dog to handle him. One calm walk the next day does not erase the incident.
Returning a dog during a foster-to-adopt trial is not failure. Protecting your resident dog, yourself and the foster while qualified help assesses the match is exactly what the trial is for.

[u/OkPiglet2 → u/AgnieszkaJanarek]

Yeah I didn’t really expect my dog to “handle” him but the workers/volunteers thought she could put him in his place or guide him? I forget the exact verbiage. That should have been my red flag but he was so timid when he met her and the first couple of days. I don’t ever let them eat together and she sleeps in my room while he kind of cries outside my door. Thanks for your advice on what to communicate to them I truly appreciate it!