Turner Classic Movies has it!
I'm watching it again on TCM, having seen it a number of other times. So, keep an eye on their schedule. Actually, you can subscribe to their monthly schedule. I do, but this one nearly snuck by me.
I recall seeing it long ago on network TV then, in the years that followed, forgetting its name, which is odd as it's rather obvious. However, I truly thought that Frank Sinatra did Wildfire's voice! In fact, when the film started today, my mom said, "That's Frank Sinatra!" *giggle* I certainly never would have identified it as Vic Morrow! Even now, listening very carefully, I can't "hear" Morrow. Very odd...
It's still a unique film: an animal movie not marketed for children though children of a certain age would enjoy this. Some of the adults' actions might be confusing, as it's true to the period it's set in, with no Fifties sensibilities added. But, I think if parents are there to explain, it should be all right. Too often, characters in period films are made to act non-period because certain things might not be PC. Or, maybe writers have no imagination and cannot picture how people might think and act "way back when".
~~MystMoonstruck~~