A cat’s eyes are pretty amazing. They allow a cat to see in near-darkness and provide her with a great ability to detect motion in order to hunt prey. But the thing that really fascinates a lot of people are those vertical, slit-shaped cat pupils. Cat pupils do much more than respond to the level of light in a room, though. Those cat pupils also give you a good sense of how your cat is feeling — emotionally and physically.
Here are a few cool things to know about cat pupils:
Arousal can be caused by many things — anger, fear and pleasure, primarily. These emotions can result in the sudden contraction of cat pupils so that they become narrow slits. You might see this if your cat encounters a catnip mouse and prepares to attack it. Even the smell of catnip itself can cause arousal in a cat that likes the stuff.
You may also see the cat pupils contract suddenly if she’s about to “kill” her favorite toy (or your toes moving around under the blankets). Anger can also cause cat pupils to contract into slits; this is usually accompanied by growling or hissing, though.
Yes, it’s true: wide cat pupils can mean both excitement and fear, so you’ll have to suss out the meaning of your cat’s wide eyes by looking at what’s going on around her and her other body language cues. For example, when my cat, Bella, gets surprised, her pupils go wide and she jumps up in the air with the classic “bottle brush tail.” Wide cat pupils can also indicate excitement. When you pull out your cat’s favorite treats, her pupils may get wide in anticipation.
On the other hand, wide cat pupils may indicate anxiety. If your cat is sitting there, looking tense (with a hunched back and her tail close to her side), and her pupils are also wide, you can assume that she’s anxious about something. You’ve probably seen this when you take your cat to the vet and she really doesn’t want to be there.
Wide cat pupils can also indicate abject terror. Maybe you’ve seen this if you’ve been in a huge thunderstorm, just before your cat runs for the smallest and darkest place she can find.
When one of the cat pupils is larger than the other, your cat has a condition called anisocoria. Anisocoria is a symptom, not a disease itself. Sometimes, it’s an emergency.
“If anisocoria occurs suddenly, you should consider this an emergency situation and seek veterinary care immediately to lessen the chance that your cat’s vision will be permanently affected,” Cheryl Yuill, DVM, MSc, CVH, writes in an article on anisocoria in cats for the VCA.
When cat pupils are different sizes, it can indicate that your cat is suffering from one of the following issues: a brain injury due to trauma (such as a fall or being hit by a car or a disease like a stroke); an injury to the surface of the eye; a problem with the nerves running to the affected eye; glaucoma, a very painful pressure buildup in the eye; inflammation of the interior of the eye; retinal disease; or even cancer. Cats may also develop anisocoria due to spastic pupil syndrome, which is associated with the feline leukemia virus.
Cat pupils are an amazingly expressive part of your feline friend’s body language repertoire. By studying your cat’s eyes along with her body language, you’ll be able to understand your cat better and avoid unwanted aggression or fear. The pupils are also a reflection of your cat’s health. Don’t hesitate to get your cat to the vet if you notice that her pupils are different sizes.
Tell us: Have you noticed your cat’s pupils changing different shapes and sizes?
Thumbnail: Photography ©manop1984 | iStock / Getty Images Plus.
This piece was originally published in 2018.