periodic bulging eyes

Question
I just got my bunny as a house pet & have recently noticed that her eyeballs sometimes seem to be swollen. They will bulge for a few minutes during which time I can see the whites of her eyes (normally only iris shows). I haven't been able to identify any related/causative factor (such as wearing her harness, which is always loose when on.)

From what I gather, she's an American Chinchilla & was born April/May.

Do you know what this could be?  Should I take her to a vet?

Answer
Dear Mitch,

A rabbit's eyes will bulge when the bunny is nervous or frightened.  But if her eyes are bulging when she is calm, or especially when she has her head down in an eating or drinking position, this could be a health problem that needs to be addressed by a good rabbit veterinarian, whom you can find here:

www.rabbit.org/vets

You don't say how old she is.  But in some older rabbits, they thymus gland becomes enlarged, forming a thymoma.  This presses on the heart and lungs, and can impinge on the descending aorta blood flow, causing blood to back up in the  head veins just a bit.  Because there is a large, venous sinus just behind the eyeballs in rabbits, this problem can cause periodic eye bulging in affected rabbits.

Other types of chest masses can also do this, including a thoracic abscess or a tumor.  Or it could be that your bunny has a genetic malformation that causes this, and nothing more might ever come of it.

But for your peace of mind, I would get her to a good, experienced rabbit vet and explain the signs you see.  The vet may wish to take chest radiographs to see if there's anything of concern, and do a general wellness exam.

I hope that helps, and that your bunny will be fine.

Dana