
Oh I can understand your frustration. I know of people whose vets have treated their animals appallingly (in my eyes) and yet they think the sun shines out of their.... Many people though haven't had some of the experiences that perhaps you or I have had. What makes me more frustrated is the poor treatment by the vet. Likely this poor girl will have recurrent lameness her whole life, due to the treatment by the vet.
I too would have to give my opinion, in all conscience I would not be able to live with myself if I didn't at least try. I wouldn't necessarily expect the owner to appreciate it though, or do anything about it. Many people feel that it is an insult to their vet to seek a second opinion, and this can be a reason they don't do it, and, as Cracar said, cost may also be a factor in this situation. I would maybe try and say that it is quite common practice to seek a second opinion, especially as the local vet is the equivalent of a GP etc....but I am sure you've done that already.
So very sad and frustrating, especially when you are seeing her in front of you day in and day out.