Exophthalmos and Orbital Diseases in Rabbits
Exophthalmos is a condition in which the rabbit's eyeballs are displaced from the orbital cavity or eye socket due to oral diseases or the development of swelling or a growth behind the eye. Typically, the eyeball is pushed forward and away from the socket, but depending on the location of the swelling, the eyeball may displaced in the backward direction on rare occasions.
Young rabbits, dwarf breeds, lop breeds, and middle-aged rabbits are more easily affected by exophthalmus due to a primary tooth or oral disease.
Symptoms and Types
The other main types of orbital disease include:
- Malpositioned eye — caused by changes in volume (loss or gain) of the contents of the eye, or abnormal extraocular muscle function
- Enophthalmos — caused by loss of orbital volume or space-occupying lesions in the front of the globe of the eye
- Strabismus — abnormal movement of eyeballs - is usually caused by improper muscle tone
The symptoms for these orbital diseases will vary but typically include a history of dental disease, incisor overgrowth, nasal discharge, and upper respiratory infection. Other symptoms include:
- Lethargy
- Depression
- Protrusion, drooping of eyelid
- Teeth grinding
- Excessive drooling
- Dropping food out of the mouth
- Facial asymmetry, possibly visible masses in rabbits with tooth root abscesses
- Change in drinking or eating behaviors (e.g., preference for soft foods)
- Hunched posture and an unwillingness to move
Diagnosis
Your veterinarian will perform a thorough physical exam and detailed evaluation on your rabbit to determine the underlying cause. X-rays of the skull and face are always recommended, and your veterinarian may include X-rays of the chest region to look for possible respiratory involvement. Orbital ultrasonography can also be used to give a more detailed image of the extent of the lesion, and computed tomography (CT) can be used for superior visualization of the structures surrounding the eyes.
A detailed oral and nasal examination will be done, with a fluid sample taken by needle aspiration from the orbit for analysis. If a mass is found in the orbital cavity, skull, or elsewhere in the body, a tissue and cell biopsy can be performed to confirm if cancer is present.
Treatment
The course of treatment will depend on the underlying cause and final diagnosis. If excessive fat pads are present behind the eyes, for example, weight reduction will be recommended. Meanwhile, antibiotics will be used for bacterial infections. And if the infection has resulted in the formation of abscesses surgery is needed, which in turn will require pain relievers (usually in the form of analgesics), along with lubricating gels for the eye-region to prevent drying of the tissue. Cancer may also be discovered in rabbits with orbital diseases; in these cases, your veterinarian will recommend consulting an oncologist.
Living and Management
It is imperative that your rabbit continue to eat during and following treatment. Softer foods that are easier to chew should be offered until your rabbit has recovered enough strength to eat harder to chew solids. In the interim, you can continue to offer your rabbit its usual pelleted diet to encourage it to eat.
Keep the fur around the face clean and dry, and allow your rabbit plenty of time to rest in a quiet space after surgery. If your rabbit is debilitated or anorectic, you will need to provide it with assisted feeding and fluid therapy. Usually, a gruel meal fed by feeding syringe is sufficient. In addition, do not feed your rabbit high-carbohydrate foods or high-fat nutritional supplements unless your veterinarian specifically advises it.
Re-evaluation will be scheduled by your doctor 7 to 10 days after surgery, and then every one to three months. In some cases, damage to the eye of eye socket can occur, resulting in loss of the eye. If pain is debilitating or chronic, your veterinarian may also recommend euthanizing the rabbit. Otherwise, lifelong treatment for underlying tooth disease is typicaly, and regular tooth trimming is indicated to avoid further complications due to overgrown teeth.