Nearly 70 dogs were used for the making of this motion picture, many of which were rescued from the pound. Several of them were adopted by crew members after filming wrapped.
The actors found the film particularly challenging to shoot due to the dog trainers constantly jumping, whistling, and shouting instructions to the dogs just outside the frame.
Most dogs were trained for two to three months, while the main dogs' training lasted nearly sixteen weeks. (about four months).
The novel upon which this movie is based was first published in 1971.
Many different types of dogs can be seen in the film: Lenny is a Bullmastiff, Georgia is a Boston Terrier, Cooper is an English Bulldog, Shep is a Border Collie, Romeo is a Chinese Crested Dog, Juliet is a Poodle and Henry is a Beauceron.