Anne The Animated Series episode 3, "The Stray", is a perfect intro to the series and carries on the spirit of the original Anne of Green Gables.
A stray dog arrives on the doorstop of Green Gables. Anne immediately falls in love with the pooch and is determined to keep it. Marilla is against the idea; they have enough animals and a dog is a great deal of responsibility. When nobody comes to claim the pet, Anne schemes to keep him. However, after a series of mishaps, Anne comes to realize that looking after a dog full-time is a lot of work.