Third Eyelid

Question
Hi Dana,

One of my mini-lop rabbits has his third eyelids protruding once in a while.  I have noticed it in the past few weeks, as sometimes it covers part of the black part of his eyes.  His eyes do not bulge all the time and I cannot see the third eyelids all the time.  I am taking him to the vet this weekend (luckily I have one that specialises in rabbits), but I was wondering if you had some ideas as to what it could be.

Thanks,

Matt  

Answer
Dear Matt,

If the eye is actually bulging to cause the nictans (third eyelid) to partly cover the bunny's eye, then there could be several different possibilities.  If it's only intermittent, then there could be something--such as a thymoma or other mass in the chest--that is impinging on the descending aorta and causing blood to back up in the large, venous sinuses behind the eye, causing the eyes to bulge.  Such a mass would have to be diagnosed via radiography.

I hope your little guy will be fine, and that this is just an idiosyncracy.  But it's a good idea to get him to a good rabbit vet for diagnosis and treatment, as necessary.

Dana