I am currently fostering a 1 year old SBTx called Star from a local shelter where she was highly stressed. I've had her for 3 weeks and she's doing great with her issues of separation anxiety, house training and hyper excitement. I've been teaching her a recall using a flexi leash and asking for a come under considerable distraction and, so far, she's been almost 100% reliable, breaking off her interest in whatever she was about and running back to me for praise and treat. She walks confidently and loves meeting other dogs and people. The only problem I sometimes have to deal with is that she occasionally appears to get spooked for no (to me at least) apparent reason - she will tuck her tail down in an inverted L shape, crouch low, goes wide eyed and rushes back and forth in a sort of frenzy. Usually I just shorten the leash, let her calm down and she very quickly returns to normal.
This morning, however, during our morning walk a hot air balloon passed quite low overhead and she again went into a fearful reaction as described above. I again shortened the leash till she was restrained close to me and stood calmly with her until the balloon had disappeared. I didn't make any fuss of her or pet her to try and reassure her, just tried to act as if there was nothing to worry about. Star seemed to loose trust in me and after we continued our walk kept out in front of me on the flexi-leash and would not respond to willingly to my recalls. After about half an hour she seemed back to normal.
I am concerned that I may have damaged our relationship in some way and that she will not trust me in future fearful situations. Can you advise me on the best way to handle unexpected, fearful events and retain my dosg's trust?