This article approaches Sirius (1944), by Olaf Stapledon, from a perspective that brings together literary animal studies and ecocriticism. The eponymous main character of this science fiction novel is a genetically-modified dog who struggles between the human and the animal realms, being unable to belong to either urban or natural spaces. I argue this work of fiction carries out an exercise of blurring boundaries, thus proposing alternatives for harmful binaries such as human-animal, city-nature, or divine-mundane. Each of these binaries is explored in three trips of the many this character experiences throughout the novel. This allows the main character to reflect on his peculiar, unique species as the singularity he is. Sirius claims it is only empathy that can help in such a task; both human and nonhuman animals are then able to rejoice in biological, cultural, and spiritual differences. Sirius’s trips are analyzed in order to look closely at (1) the dog’s reflections on humankind while being in London, (2) his becoming a wolf, dog, and human at the same time in the woods, and (3) music as the ideal tool to articulate one’s spirituality based on a reconnection with an almost lost biodiversity.