In a lot of cases I think it might be helpful. The vets
can speak more clearly on this issue, but my long discouraging exploration of
lameness and diagnostics suggests that it is just one of many procedures that
may or may not help. It also seems to me that there are a variety of kinds
of machines with a variety of abilities, depending on size, etc. At first,
I thought some permitted standing (not fully anesthetized) MRI's, but now it
seems they all require full anesthesia, which certainly carries it's own
risks.
I just read an article on MRI for horses available at Arizona Equine in
Gilbert, AZ. If I had a problem (knock on wood I don't have one now), I
think I would opt for this diagnostic.