Hoofbeats of Vengeance

Rex the Wonder Horse returns, with Jack Perrin and a couple of drunken burros as his sidekicks. Rex was the mount of a Mountie, but the man was bushwhacked, and now Rex seeks vengeance on his slayer: Al Ferguson, who's a smuggler, as well as the foreman of Helen Foster's ranch. Rex knows when and where the smugglers are out, unlike the stupid Mounties, and so they follow him whenever he shows up.... and miss the bad guys. But Jack Perrin is the new Mountie in town, and he wants to capture his old partner's murderer and pitch some woo to Miss Foster. He has a clue about the smugglers, so he goes to Ferguson for a job and is immediately recognized and imprisoned.

Fortunately, all these dumb humans have Rex to watch out for them. Ferguson keeps having panic attacks about Rex, who holds intelligent conversations with Ferguson's horse then beats it into the ground, then leads the Mounties to the ranch. Will they make it, or will they fall on their hats?

It's co-written by George H. Plympton, who has IMDb credits for 293 scripts, including FLASH GORDON CONQUERS THE UNIVERSE and THE THREE STOOGES FOLLIES. The copy I looked at was in good shape, and one of four movies in vol. 5 of ACCIDENTALLY PRESERVED, with an unsurprisingly fine score by Jon Mirsalis.