Eye proptosis in dogs is caused by trauma, and pugs are more susceptible to it than many other breeds because of the shape of their heads. Their extremely short snouts and prominent eye sockets do not offer much protection.

Pugs are a brachycephalic breed, which means that they have short, broad skulls and flat noses. Due to the shape of their skulls, even small amounts of force like a scuffle between two dogs can cause their eyes to pop out of their heads. Traumatic proptosis is a veterinary emergency. According to Noelle La Croix, DVM, it often results in blindness, but brachycephalic dogs often have a better prognosis than other breeds.