Help! My Cats Has One Pupil That Dilates Bigger Than the Other! (Vet Answered)
This question has been answered by a vet
Veterinarian & Animal Behaviorist
With nearly two decades in veterinary medicine, Dr. Paola brings hands-on experience across multiple species. A graduate of the University of Guadalajara, she specializes in preventive care, animal welfare, and positive reinforcement training.
The Question
“My cat Trixie has one pupil that dilates quite big and the other only a little bit. She’s 2 years old. Seems like she can see no problem. Should we take her to be seen by the vet or watch out for other signs/symptoms? “– Jackson
Quick Info about Trixie
Hey Jackson,
Noticing one pupil larger than the other can be alarming, and you are right to pay close attention. Uneven pupil size, called anisocoria, can appear harmless at first, yet in veterinary medicine, it is treated as an important clinical sign because it can be linked to conditions involving the eye itself or the nervous system. Even when a young cat like Trixie seems to see normally, underlying issues such as ocular inflammation, retinal disease, or neurologic changes can be present without obvious discomfort.
Because the eyes are so delicate and the causes of anisocoria vary widely, this is not something to watch and wait. Her eyes need to be examined with proper equipment and lighting. Early assessment helps protect her vision and ensures that anything needing treatment is identified promptly. You are doing the right thing by taking this seriously, and with timely attention, most causes can be addressed in a way that keeps Trixie comfortable and safe.
– Dr. Paola