The Adventures of Black Beauty (1972)

S2E26 The Last Roundup

Mr. Coomb's dog gets hurt in a trap set by the squire, leaving him worried about how he'll manage his sheep. Dr. Gordon steps in and offers the help of Kevin and Albert, who try their hardest, but soon, the sheep begin to vanish without explanation. Albert discovers a smuggling scheme at play, but he requires Beauty's assistance to gather the proof he needs.