Here's another thread where we discussed Clint's horses.http://www.clinteastwood.org/forums/index.php?topic=5308.0
As Lilly said in that thread:
I think horses are usually supplied by a wrangler who specialises in working for the film industry. In the "making of" featurette on the Unforgiven DVD there is a brief interview with the wrangler for that movie, who says they deliberately picked a flea-bitten grey for Munny's old horse. I would imagine that most of the horses stay with the wrangler as they would be valued animals accustomed to working on movie sets.
I've just re-watched the featurette Lilly mentions, and I can confirm what Canadian Lady says: the head wrangler was indeed John Scott, and he's interviewed there:
For Clint's horse, we had to find a certain look of the horse, and we kind of wound up with a sort of flea-bitten gray type horse, and as I say going back to the early days, there weren't finely bred, good-headed type horses. There were a sort of a hammer head and a long head on them, kind of a bump in their forehead and sort of a Roman nose, so we had to strive to find a horse that's gentle, got a certain look to him, a bit of a character look, and not a fancy-looking horse.
After the three "spaghetti Westerns" at the beginning of Clint's career, which were shot in Italy and Spain, no two of his Westerns were shot in the same locale, so I'm sure, as Canadian Lady says, he used "the best local horse trainers and horses," in whatever location the crew was in.
In one case, at least, he did continue riding the horse for a while after the shoot was over. That would be Pale Rider
. As I commented in another thread:
... Eastwood was hurt in a fall while riding his horse from Pale Rider, but as far as I know that was after the shoot was over. Most sources say he suffered a dislocated shoulder.