Double Merle - Unequal Pupil Size?

[Ohalani]

Does anyone know if unequal pupils are a known double merle eye defect? Ex. A dog with one normal sized pupil and one small pupil?  I know that double merles can have a lot of eye problems (+deafness) including small eyes, no eyes, starburst pupils, etc... but I don't know about the unequal pupils specifically. I've been reading about double merles on various websites, but none mention unequal pupils. I did find out that there are plenty of non-merle related causes of unequal sized pupils, including cancer, head trauma, infection, old age, etc..

I have a red merle rescue dog (probably not part Border Collie - although I know nothing about his history, and some people have suggested he might be part BC) who is over 60% white. He has light amber eyes with pale blue marbling. Because he has so much white, I've always wondered if he is just a Piebald or a double merle.  His pupils are unequal - one smaller and one larger. I didn't think too much about this, but now that I've done some research and know that this can be a symptom of serious health problems, I'm going to get him checked out by my vet ASAP. As far as I can tell, he sees and hears fine. So now I'm wondering if the pupil thing is another indicator that he could be a double merle, or if he has some other potentially serious health issue.

[Hooper2]

Well, this is one of many places where you could have him genetically tested to see if he's a double merle, although if he's anywhere near 50 % pigmented, I would bet that he's not.  Of course, determining if he's a double merle doesn't really answer your underlying question about the unequal pupil size, but if you find out he's not a double merle you could at least rule that out.  You don't say how long you've had your dog, or how old you think he is, but I'm wondering if this is recent or if his eyes have always been like this.  If it's a recent development, then I would definitely be concerned.  Is there a canine ophthalmologist near where you live?  If so, I would go there rather than to a general practice vet. 

[Ohalani]

Thanks for your reply. I was looking at the Merle gene test UC Davis offers. You're right, I was thinking I could at least rule out the possibility of double merle if I do the test. If nothing else, it would be interesting to know.

I've had my dog for 2 years, and I'm guessing he was about a year when I got him. So he's about 3.  I'm honestly not sure when he developed the unequal pupils - or if he was even that way when I adopted him. I should have been more observant, but it isn't a huge difference in size.  My sister told me she thought his pupils were unequal about 6 months ago, but I wasn't sure there was an actual difference and I didn't think too much about it.  A few days ago I noticed that there was a definite difference in pupil size, and that's when I looked it up and learned that it could actually be something serious. Not sure if we have a canine ophthalmologist here. I'll ask around.

[Ohalani]

Update: I took my dog to my regular vet, and she couldn't give me many answers. Basically I need to take him to an ophthalmologist, and the ophthalmologist only comes to our island every 6 months. The vet did a physical exam, and that was fine. Both his pupils react to light, and he sees out of both eyes. But she agrees that the right one is larger than the right. I'll probably do the double merle test just to rule that out.