Aussie as a pet name almost certainly means one thing: the owner has an Australian Shepherd, and they made the logical but obvious choice. It's the dog-name equivalent of naming your golden retriever Goldie — not subtle, but entirely affectionate, and far more common in the licensing data than you'd expect.
The Breed-Name Loop
Australian Shepherds — Aussies in breed shorthand — are one of the most popular breeds in the United States, and a meaningful percentage of owners simply transfer the breed nickname to the individual animal. This creates a self-referential naming pattern: the dog's name is the breed's name is the country's name. It's a loop of affection that makes complete sense from the inside.
When It's Not an Australian Shepherd
Occasionally Aussie appears on dogs with Australian connections that aren't Australian Shepherds — Australian Cattle Dogs, Australian Terriers, or dogs owned by Australian expats. And occasionally it appears on dogs with no Australian connection at all, where the owner just liked the sound and the vibe. The name reads as cheerful and outdoorsy regardless of the breed attached to it.
The Honest Assessment
Aussie as a name works, but it's one of the more predictable choices available to Australian Shepherd owners. If you want something that references the breed's heritage without being the literal breed nickname, consider names rooted in Australian geography or culture: Sydney, Darwin, or Bush occupy the same space with more individual character.