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Clinical signs of an external otitis may also be present.
Otitis media and interna often develop when bacteria, such as Mycoplasma pulmonis, Streptobacillus moniliformis, or Psuedomonas aeruginosa, and viruses travel from the naso-pharynx through the eustachian tubes to involve the lining of the ear. As the infection progresses to involve the labyrinth structure of the inner ear, inflammation to the vestibular nerve and swelling of the surrounding tissues results in “torticollis” or a tilting of the head. This tilting is most often directed towards the side of the affected ear. It is sometimes referred to as “Head Tilt,” or “Wry Neck” (a neuro-muscular response seen primarily in rabbits).
In most cases, when treated promptly with systemic antibiotics to combat infection, as well as a corticosteroid to reduce the swelling of tissue, the head tilt will disappear in a matter of days. However, it is not unusual in some cases for the head tilt to remain throughout the rat’s life. This permanent “tilt” does not seem to pose a significant problem for rats, as they are able to adjust to it very quickly. Where left untreated, the condition could worsen resulting in the loss of balance for the rat, rolling rather than being able to stand or walk, and the inability to feed or care for itself.
It is important to note that there are other conditions that can result in “head tilt” besides infections of the ear such as: brain injuries (e.g. strokes), pituitary tumors, or trauma. Any disease process which can cause obstruction or inflammation of the inner ear can lead to head tilt.
A final note, when attempting to resolve otitis media or interna, the underlying cause should be determined and treated if possible.
Assess rat’s balance. Head will often be tilted towards side of affected ear.
Visualization with otoscope may show discoloration, bulging, or rupture of the tympanic membrane. Fluid or exudate/pus may be present in the tympanic cavity. A foul or sweet smell may indicate the presence of bacteria or yeast.
If possible obtain exudate for culture and sensitivity.
*Note: If planning to use an aminoglycoside, in treatment, it is necessary to cleanse or remove exudate since drugs in this group are inactivated in the presence of pus.
Be sure to dry ear before applying a cream or ointment.
Topical agents are varied and use may be based on the organism(s) or condition being treated.
Some of those agents the veterinarian may select are topical otic antibiotics or antifungals that may include a steroid such as: Treasaderm (containing neomycin sulfate, thiabendazole, and dexamethasone), or Gentocin Otic (containing gentamicin sulfate, and betamethasone valerate), or topical otics such as: Baytril Otic (enrofloxacin/silver sulfadiazine) primarily used for Gram-neg. infection, or Silver sulfadiazine (Silvadene), that may require an addition of a systemic or topical steroid to the treatment.
In addition, an agent such as Tris-EDTA may be instilled in the ear canal prior to the use of topical otic antibiotics to enhance their activity.
*Note: The use of a corticosteroid either topically or systemically can aid in reducing exudate and tissue growth as well as relieve itching. Its use may predispose to yeast infections; however, the benefit of using a corticosteroid, in many cases with rats, far outweighs the risk. If yeast is present or of concern the veterinarian may choose to include a topical or systemic antifungal medication (already included in some topical medications) such as: ketoconazole or metronidazole.
Posted on June 25, 2003, 09:28,
Last updated on May 22, 2012, 15:59
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