By Leticia Materi, PhD, DVM
In order to detect signs of illness early, I strongly encourage all rabbit owners to do routine exams at home on their pets. This is especially true in older animals, because they are more at risk for developing problems. In addition to doing a hands-on examination, taking the time to do a distant observation of your pet can yield valuable information.
One method for evaluating the eyes is to look at the face of the rabbit from in front as well as from above. This allows us to detect displacement of the eyes in the orbit. This can happen if an eye enlarges or if it is being pushed out of place by some disease process.
Reasons Rabbit Eyes Bulge
There are a few reasons why a rabbit’s eyes may appear enlarged or bulging.
This is a condition in which the eyeball itself enlarges. Under normal conditions, the eye produces fluid within the interior at the same rate that fluid drains. If something happens that disrupts the draining of the fluid, then the eyeball starts to swell from excess fluid accumulation. The can happen if there is a change to the lens, inflammation or bleeding in the eye. In order to determine if a rabbit has glaucoma, veterinarians use special instruments to examine the intraocular pressure of the eye.
2. Abscess Formation
Behind the eyeball is an area known as the retrobulbar space. When the root of an upper molar becomes infected, the pus formed often travels to this space. Increasing pressure forces the eye outward and owners may notice that the third eyelid is more visible than normal. This is a common reason for one eye to appear as though it is bulging.
3. Cardiac Disease
There is a large blood sinus in the retrobulbar space. When the heart begins to fail, blood will back up and cause that sinus to expand, which causes the eye to shift outward. Thus, both eyes appear to bulge and it is made worse when the head is tipped downward.
In some instances, the thymus gland (which lies just in front of the heart) becomes cancerous and enlarges. This mass ultimately compresses the large vessels draining blood from the head and causing dilation of the sinus behind the eyes. Again, both eyes appear to bulge in affected rabbits.
Diagnosing The Reason For Bulging Eyes
In order to determine what is causing the eyes to change, veterinarians recommend tests, such as radiographs (X-rays), ultrasound, CT scans or even MRIs. Treatment is ultimately determined by the final diagnosis.
- Glaucoma can often be controlled in the initial stages by medications to control fluid production and drainage in the eye. If it cannot be controlled, removal of the diseased eye may be recommended.
- Retrobulbar abscesses due to tooth root disease are very challenging to treat and often require removal of the eye and the affected teeth.
- Depending on the nature of the heart disease, various medications can be used to control the signs of heart failure.
- Treatments such as surgery, radiation therapy, and therapeutic aspiration of cystic thymomas have been reported.
Please contact your veterinarian if you observe changes to your rabbit’s eyes.
Note: All articles by Dr. Materi are meant for educational purposes only and in no way represent any particular individual or case. They are not for diagnostic purposes. If your pet is sick, please take him or her to a veterinarian.