Teazel was Edward Lunn's pet dog. While out hunting in September 1909, Teazel and Lunn were captured by Zygons, who used their body-prints to assume their appearances.
Teazel's appearance was taken by Brelarn, warlord of the Zygons. After being rescued, Teazel guarded Edward and his family. (PROSE: Sting of the Zygons)