After the actors recorded their voices, animating and filming commenced at Amblimation in London on March 1, 1993. To have a source for the dogs' character animation to be based on, the filmmakers brought in about seven Siberian Huskies and videotaped them walking around in the studio. Although most of the film's animation was hand-drawn, the animators used Toonz to improve the graphics, and also created the snowstorms using an early CGI particle animation system. Additional animation was done by the Danish studio A. Film Production. James Horner composed the film's music, including the film's only song, "Reach for the Light", sung by Steve Winwood, which plays over the film's closing credits.