The Rifleman - Season 1 - Eps 15: The Pet
Ward Haskins guns down Joe Flecker, who has evidence that could be used to blackmail him. Haskins thinks the information was given to Lucas, since he brought Flecker to the doctor before he died. Stirred up by Haskins behavior, Lucas goes through Flecker's things, finding a wanted poster for Haskins in the sole of Flecker's boot. He also finds Doc Burrage drinking. Doc is discouraged because three children have died of an anthrax epidemic that he has the new serum for, but nobody is willing to allow him to administer it in time. Haskins rides out to the ranch and is bitten by Flecker's horse, which is now believed to have anthrax. Mark overhears about how anthrax always causes death and is worried because he had bitten by Flecker's horse, also.
About The Rifleman

Title: The Rifleman
First Air Date: 1958-09-30
Last Air Date: 1963-04-08
Status: Ended
Rating: 7/10 (from 46 votes)
Language: EN
Seasons: 5
Total Episodes: 168
Network: ABC
Genres: Action & Adventure, Western, Family
Production Companies: Four Stars Productions
Synopsis
The Rifleman is an American Western television program starring Chuck Connors as rancher Lucas McCain and Johnny Crawford as his son, Mark McCain. It was set in the 1880s in the town of North Fork, New Mexico Territory. The show was filmed in black-and-white, half-hour episodes. "The Rifleman" aired on ABC from September 30, 1958 to April 8, 1963 as a production of Four Star Television. It was one of the first prime time series to have a widowed parent raise a child.
Cast

Chuck Connors
Lucas McCain

Johnny Crawford
Mark McCain

Paul Fix
Micah Torrance