What type of trauma is most likely in a dog with anisocoria after being hit by a car?

Anisocoria, which is characterized by unequal pupil sizes, can be indicative of neurological dysfunction, particularly related to head trauma. When a dog experiences a traumatic event, such as being hit by a car, it is common for the brain to sustain injury, especially if there is an impact to the head.

In this scenario, the presence of anisocoria strongly suggests that the trauma has affected the areas of the brain that control neurological responses, such as those governing pupillary size and response. Head trauma can lead to a range of complications, including intracranial hemorrhage or concussion, all of which can manifest as changes in pupil size and reactivity.

Other types of trauma, such as a ruptured bladder, pneumothorax, or splenic torsion, do not typically result in anisocoria. These conditions are more likely to manifest through other clinical signs and symptoms that do not involve direct changes to the neurological function related to cranial injuries. Hence, head trauma is the most plausible explanation for anisocoria in this context.