Goat dog

The Goat Dog first seen in The Tales of Ba Sing Se, when Aang creates a make-shift zoo for Kenji, an old, seemingly run-down zoo keeper. It has only one depute in the series, appearing comically next to the hissing Fluffykins.

Anatomy
The Goat Dog has a short build, drenched in long white fur. Its pelt on its face is curtained - splitting at the snout. It has short spiked ears, and a large triangular nose, as well as hoofed feet and stubby legs.

Connection
The animal seems to appear similar to a Yorkshire Terrier of the real world. It has characteristics of goats as well, and maybe even bison.