I came across this wonderful story with video, about a kitten and dog.
From the video description:
The filmmaker of “Ricky” has a dog, Romy, who is afraid of other dogs, but she loves cats. Last year he adopted a friend for her: a cat named Ricky. This film is narrated — but unscripted — by his 7-year-old neighbor, Willa, and follows Ricky and Romy as they get to know each other.
Nothing like a ‘best bud.’