* Breed Selection: Over centuries, breeders have selectively bred for certain traits in Chihuahuas. Large eyes are considered a desirable feature, often associated with cuteness and alertness.
* Proportion: Their bodies are small, so their eyes appear proportionally larger compared to their overall size. This contributes to their appealing appearance.
* Sight: While they don't have *better* vision than other dogs, the large eyes could potentially offer a wider field of view, contributing to their alertness.
* Socialization: Large eyes can be a form of "cute aggression," triggering nurturing instincts in humans. This likely helped early Chihuahuas form strong bonds with humans and be valued as companions.
It's important to note that some Chihuahua breeds are prone to eye problems, such as dry eye or cherry eye, due to the shape and size of their eyes. These are health issues to be aware of and managed by a veterinarian if they arise.