Options for Treament of Middle Ear Infections in Pet Rats

Middle Ear Infections in Pet Rats (Rattus norvegicus)
Dr. William ( Bill ) J Langhofer
DVM Purdue University 1998
The Scottsdale Veterinary Clinic
7311 E Thomas Rd, Scottsdale, AZ 85251
TSVCpets.com 480-945-8484

Middle ear infections are very common in pet rats and can be a difficult condition to resolve. We will typically diagnose a new middle ear infection in pet rats in our hospital 2-3 times per week. Dog/cat veterinarians are familiar with treating external ear infections; however, middle ear infections require longer therapy and different medications to resolve. Usually these infections arise from a previous upper respiratory infection (sinus infection) or pneumonia. These infections are similar to the ear infections that human children face and require many of the same treatments to resolve. These infections are not only painful, but are also potentially deadly, if the infection starts to affect the brain. This condition is many times misdiagnosed as a pituitary tumor. The symptoms that your pet has a middle ear infection may include: difficulty with hearing, red discharge from the eyes, sneezing, difficulty breathing, scratching the ears, head tilt, abnormal smell from the ears, seizures, lethargy, and depression.
The middle ear of a rat is large due to their nocturnal nature. This large middle ear is a great place for bacteria to reside and start an ear infection. It is suspected that these infections arise from the eustachian tube secondarily to a sinus infection. The eustachian tube becomes blocked from the pus/infection, causing increased pressure in the middle ear, which will cause the symptoms of neurological disease and a head tilt. The head tilt may then become a permanent symptom or may resolve once the ear drum (tympanic membrane) ruptures. It is difficult to resolve these infections since the blood supply to the middle ear is very small, preventing the necessary concentration of antibiotics to resolve the infection.
These infections are fairly easy to diagnose with an otoscopic evaluation. Occasionally a rat will require anesthesia to evaluate the ears if they will not hold still for the examination. If wax is in the ear, anesthesia may be required to remove the wax to evaluate the ear drum (tympanic membrane). Radiographs (x-rays) may also be helpful in the evaluation of the tympanic bulla.

Treatment options:

1. Oral Antibiotics- We generally recommend a combination of clavamox/baytril or doxycycline/zithromax; however we have also used combinations of penicillin, clindamyacin, metronidazole, and other antibiotics depending on response to therapy, cytological evaluation of the pus from the ears, and bacterial culture. Oral antibiotics are many times not as effective as topical medications if the ear infection is the only condition that we are treating. If pneumonia or a sinus infection is present oral antibiotics are necessary.
2. Topical antibiotics- These are placed directly into the ear to treat the ear infection. This is more effective if the ear drum (tympanic membrane) is ruptured. We typically use ciprofloxacin or neo-poly dex ophthalmic drops.
3. Topical wax remover- Debrox is effective at aiding in the removal of wax from the ears allowing the antibiotics to penetrate to the middle ear more effectively. This may be purchased over the counter and is also helpful in removing wax from the ears of rats that are paralyzed or arthritic and can no longer scratch the wax from their own ears.
4. Ear flush- this helps remove pus from the middle ear and opens the eustacian tube, but can be dangerous since rats are obligate nose breathing animals and this technique is usually performed with anesthesia.
5. Rupture of the ear drum- this is recommended to release pressure in the middle ear, and to allow topical medications to reach the middle ear. This procedure does have some risks and must be performed with anesthesia. This procedure can be very effective at resolving head tilts secondary to the middle ear infections. This could potentially cause death if the skull was fractured, but I have never seen this side effect.
6. Ear tubes- these are placed into the middle ear to continue to allow the pus to drain from the ears, and prevent the ear drum from healing. This allows topical meds to be administered for a longer period of time. The problem with these tubes is that very few veterinarians have used them and they clog with debris easily. They may need maintenance.
7. Anti-inflammatory medications- Metacam is both a pain reliever and anti-inflammatory and is commonly used for ear infections. Prednisone is a strong anti-inflammatory medication and helps reduce inflammation in the ear.
8. Euthanasia- Ear infections are reported to be very painful in humans. If the rat is not responding to therapy, is neurological, or will not tolerate medications, a humane euthanasia may be recommended for this condition.

The treatment of choice depends on the rat, their human, and their medical conditions. We typically use a combination of oral antibiotics/anti-inflammatory medication, and topical medications. If the infection is not responding to the oral meds we typically will place the ear tube, suction pus from the middle ear, and start more aggressive topical therapy. The ear drum is almost always ruptured by the doctor with anesthesia if the rat is neurological (head tilt), especially if the ear drum is bulging from the pressure of the pus in the middle ear. The ear tubes appear to be very useful and helpful as long the owner continues topical medications and the tubes are rechecked to make sure they are not clogged. Due to their obligate nasal breathing nature, the difficulty in treating middle ear infections, and the immunosuppressive nature of rat viral/bacterial infections makes middle ear infections difficult to resolve and may require life long antibiotics/therapy to control these infections.