Medically reviewed by Johnstone M. Kim, MD Mydriasis occurs when the pupil remains dilated (widened) and doesn't respond to light changes in an environment. It can happen due to an injury, medications ...

When it comes to the eyes, the sympathetic nervous system controls the proper functioning of a dog’s eye muscles, pupils, and other surrounding parts. “Horner’s Syndrome is where there is an ...

Following acute multiple trauma, hypothalamic stimulation of the sympathetic nervous system and adrenal glands causes an increase in circulating corticoids and catecholamines, or a stress response.