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Difference in pupil sizes

My 9 yr old cat suddenly has a difference in the size of his pupils.  He is eating and acting ok so far.  I have noticed alot of twitching in his tail when he is resting.  Anyone else experienced this?
9 Responses
436973 tn?1217950689
is it possible he has suffered any head-trauma?  My kitty did that when she had a concussion.  But she had other symptoms as well.  She was  angry and scared,  eyes also watered and she went and hid.  I would just keep observing him closely.
Avatar universal
Hi there.  I'm sorry to hear about your cat.  My sister noticed one of my parents' cats pupils was bigger than the other, and we knew it hadn't always been that way.  I don't want to scare you but please take your cat to the vet.  Pupils of different size can sometimes be an indication of a serious problem.  I hope it turns out to be nothing, but it really is worth getting checked.

I hope everything works out.
Avatar universal
Thanks.  I did indeed take my cat to an emergency vet.  They said it is Horoner's syndrom and could be from stress, or even worse, a lesion in his central nervous system.  He is being monitored closely since the symptoms were so sudden.  I've just never seen anything like it before, and I have had cats my whole life.
436973 tn?1217950689
Oh dear!  I'm sorry to hear that.  So scary.  
441382 tn?1452814169
Pupils of differing sizes is a condition known as "Horner's Syndrome", and it's important to remember that it is not a disease in and of itself, it is a symptom of some other underlying cause.

There are several things that could cause it, and all of them require a trip to the veterinarian to try to figure out what it is that is causing it.  Head trauma can cause the pupils to be diffferent sizes.  It can be caused by anything from getting bumped by a car to getting into a scrap with a dog and getting shaken, there's any number of types of head trauma.  It can also be caused by a swelling that is pressing on a nerve, and that swelling can be caused by something minor or it can be caused by something as serious as a tumor.  That's why it's so important to have a vet check out any animal that has Horner's Syndrome, because early detection of a tumor can mean the difference between survival of the animal and losing the animal.

The good news is, if it is caused by a head trauma, it usually resolves itself within a couple of days to a week.  As soon as the swelling goes down, the pupils return to normal.  With a tumor, naturally, it's a bit different, that's why it's so important to figure out early on what the cause is,

Avatar universal
Just a quick update.  I took my cat for his 2nd checkup on the condition.  The vet seems to think he had an aneurysm.  She also thinks since the pupil is correcting, that the aneurysm is resolving itself.  I really hope so.  It was a scary thing to have happen to him.  He is also starting to act like his old self.....running around and chasing all his toy mice.
Thanks again for all the advice and concern.
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