Abnormal Flow of Tears Due to Nasal Duct Blockage in Rabbits
Epiphora in Rabbits
Epiphora is characterized by an abnormal flow of tears from the eyes, usually occurring as a result of poor eyelid function, blockage of the nasal and eye portion of the tear ducts (nasolacrimal), or eye infection or inflammation, which may all be precipitated by by dental disease or tooth abscess. As rabbits have only one tear duct -- located very close to the tooth and gums -- the duct can be easily blocked due to oral disease (longtooth impaction is also very common in rabbits). Epiphora may occur also due to longstanding respiratory disorders that block the nasal passages.
Congenital tooth malocclusion, and congenital eyelid deformities are usually seen in young rabbits. Middle-aged rabbits, meanwhile, usually suffer from cheek tooth elongation and subsequent epiphora. And dwarf and lop breeds often show congenital tooth malocclusion, exposing them to blocked tear ducts. Dwarf and Himalayan breeds also often suffer from glaucoma; more rarely, glaucoma affects the Rex and New Zealand White breeds.
Symptoms and Types
Rabbits suffering from epiphora will typically have a history of dental disease, incisor overgrowth, and upper respiratory infection. Other common symptoms associated with epiphora include:
- Hunched posture
- Constant hiding or unwillingness to move
- Inability to keep food in the mouth (i.e., constantly dropping food)
- Loss of hair, crusts, and matted fur around the face
- Red eyes, sometimes with thick discharge
- Bulging eyeballs and facial masses (especially those with tooth root abscesses)
There are various oral and eye dysfunctions that may lead to epiphora, including:
- Abnormal formation of nasal ducts and eye structure
- Nose inflammation or sinusitis
- Injury or fractures of the lacrimal or maxillary bones (the bones close to the eye orbits/tear ducts and the upper jaw, respectively)
- Tumors in the conjunctiva, medial eyelids, nasal cavity, maxillary bone, sinuses
- Foreign bodies in the eye (e.g., hay, litter, bedding)
- Exposure to chemicals used for home or cage cleaning
- Conjunctivitis (inflammation of the lining of the eyeball)
- Glaucoma (high fluid pressure on the eyeball)
- Paralysis of the facial nerves
Your veterinarian will perform a thorough physical exam on your rabbit, taking into account the background history of symptoms and possible incidents that might have led to this condition, such as dental problems or respiratory infections. A sample of fluid and/or discharge will then be taken from the rabit's eyes and nasal passages for bacterial culture and analysis of body fluid, which will help to diagnostically differentiate from other conditions that cause discharge from the eye.
For visual diagnostics, your veterinarian can use X-rays of the skull to examine your rabbit for tumors or injuries to the bones of the skull, but computed tomography (CT) imaging is better than X-rays for localizing any obstructions and to characterize any associated lesions that are present. If an obstruction appears to be present, a nasal duct flush will confirm obstruction and may also dislodge the foreign material, if present. Meanwhile, a fluorescein stain, a non-invasive dye that shows details of the eye under blue light, may be used to examine the eye for abrasions or foreign objects.
In addition to treating the primary eye disease (conjunctivitis, ulcerative keratitis, uveitis) or obstructing lesion (nasal or sinus mass), your veterinarian may prescribe pain relievers and antibiotics.
Living and Management
Recurrence is common in rabbits with nasolacrimal (the nasal cavity and the lacrimal/tear ducts) obstruction, but early detection, intervention, and treatment provide a better long-term prognosis. Moreover, keeping the animal's face clean and dry is crucial for preventing complications.
Conversely, rabbits with severe dental disease (especially those with tooth root abscesses and severe bone loss) have limited chance of recovery. In some cases, the nasolacrimal duct may become completely obstructed. Depending on the severity of the underlying cause, a rabbit with epiphora will require significant monetary and time investment. In some cases, epiphora may even be lifelong.
Featured Image: iStock.com/kerkla
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