In all 3 series, Charles (Chuck) P Eisenmann owned and trained the German Shepherds used. The first series starred London (the dog) and has some close relatives, Toro, Litlon, and Thorn. Several dogs were used in the second series but credit was given to “London” (this was done so the best dog for the job needed could be used). All of the dogs are German Shepherds with “reverse mask” markings (meaning areas that are typically dark on a German Shepherd (jaw, throat, chest) are light in color.
The series is compared to Lassie, where a stray dog befriends people in distress in each episode and then goes on his way (despite attempts for people to adopt him). His duties ranged from rescuing people to “secret agent” type acts. There was no name given for the dog but people referred to him as “Hobo”. The second series also had several guest stars including DeForest Kelley (Bones from the original Star Trek), Leslie Nielsen (long time comedic actor), and a young Mike Myers (Saturday Night Live, Wayne’s World, and other comedy) made his debut on the show.
Eisenmann trained his dogs in three languages (English, German, and French) and had them trained to be able to perform multiple tasks with one command as well as recognizing different colors (which is not easy for a dog considering they only see in shades of yellow, blue, and gray (as seen below – click to see the full sized chart)).
The original series is available on DVD in color (except the opening sequence, which is only in black and white). Despite airing in black and white, the series was produced in color but was aired in black and white. The first two seasons for the second series were released in 2010 for region 2 players (Europe, Middle East, Japan, South Africa, and a few other countries). Season 1 was also released for region 4 players (Mexico, Central America, South America, New Zealand, Australia, etc.). Multi region players should be able to play them (but don’t quote me on that). No other versions of either series were released by the studio.