My Cats Eyes Are Always Fully Dilated. But occasional dilation can be caused by contentment, excitement, and most often the level of light in her surroundings. I think she has allergies because she sneezes a lot and always seems to have conjunctivitis, and now we have noticed that for the past several days her eyes have been constantly fully dilated!
Dilated eyes (actually the pupils) look like the eyes in the photo below. Certain diseases, including trouble in a cat's nervous system, can cause the pupils to be noticeably different sizes. Routine blood tests should always be run to check for concurrent or underlying diseases such as kidney disease.
My house is quite dim, even with lights on, so this may be the cause but looking back through photos to the summer, they were constricted when they were supposed to be (and also in real direct sunlight now).
Learn more about the symptoms and treatment of the condition here. Sometimes dilated pupils can be a signal that something's not quite right. My cat was injured 2 months ago and from the injury her right pupil is always dilated. He also has nystagmus in both eyes.
