The Dog Who was a Cat Inside is a special animal. The dog and cat live together in the same body, but this causes conflict. When the dog tries to make friends with other dogs, the cat goes to sleep, so he can’t join in with their games and when the cat meets a cat friend, the dog barks and chases him off. The Dog Who was a Cat Inside feels lonely and rejected by all other animals. As it sits dejectedly besides the river, the Dog and Cat have a furious argument and fall into the water. At first they struggle against each other, but eventually they realise that by swimming together they can save themselves.

Siri Melchior says, The Dog Who was a Cat Inside is based on an illustration I did for the Danish proverb "Don’t judge a dog by its fur". The idea for the film developed from playing with the theme of cats and dogs. The difference between these two animals came to represent inner conflict, and the story is about learning to live with it. The visual style is inspired by Cubism and how that style can illustrate many facets of the same thing at once. I worked with both shapes and textures inspired by Cubism to create the feeling of movement and space.

The animation is a mixture of traditional and painted drawn animation and 3D computer animation. The dog / cat character was animated by hand, painted and scanned into the computer. After being cleaned up and manipulated in Photoshop, the drawings were edited using Premiere and composited with cut-out animation in 3D Studio Max.