I had a similar experinece when Joly was not much older than Tinkerbell and hope that she remains unaffected as Joly is.
We used to go to a small dog training classOnly about 10 dogs in all), run by a competitor, rather than a professional, but the class is very good, as it's aimed at show obedience and not bad behaviour.
As there was only one class, I paid a much reduced fee and Joly only had a few very short work sessions and with me and with, Andy,the trainer. Joly was coming back to me, after doing some heelwork and a fuss, with Andy, when a german shepherd, whom his owner later admitted disliked puppies, leapt up and grabbed him by the scruff. I'm told that he was shaken hard, but I was too shocked, as was everyone else, to notice.
Luckily Joly's screams startled Jay, who dropped him and Joly ran away, in a sort of trance, unable to recognize anyone, though most people there usually made a fuss of him. However, Andy managed to scoop him up and after half an hour he was back to normal, which could not be said for the rest of us.
Jay's owner was experinced with the breed and he was very human friendly, the only contratemps we ever saw being with a Doberman of equal size and age (this only mutual barking). He never even seemed to bother with the other dogs there and was lazy about his work, too, prefering a snooze. However, his owner was aware of his attitude to pups and should not have let him offlead, knowing that a young pup was about. She took him out straight away and never brought him back.
Amazingly, she risked getting a puppy herself (one was booked at the time) and was going to leave him, crated, but home alone with jay, for some hours each day. All went well, I gather, as I saw her last year, when she explained that the future show dog hadn't turned out as expected (ear fault).
It was Andy's wife who told me that Joly had actually been shaken and said that everyone was amazed at how calmly I'd taken things, but there was nothing to be done; Joly was unhurt, as his thick fluff saved him and Jay's owner had learned her lesson. She wa svery concerned about Joly and , having removed Jay, satyed for the rest of the session.
This was a case of an owner being too soft. Training should be done with kindness, but some dogs need the handler to be firm and she was not. Jay always worked better with someone else, who didn't ask him to come close, sit etc.