Treatment of Pseudomonas otitis in the dog (Sponsored by Pfizer) - Veterinary Medicine
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Treatment of Pseudomonas otitis in the dog (Sponsored by Pfizer)

Clinical Edge

I find it useful to conduct computed tomography (CT) or magnetic resonance imaging (MRI) on the ear canal and middle ear as a guide to the most appropriate therapy. For example, if considerable cartilage calcification is found in the external ear canal or bony changes are present in the tympanic bulla, then the prognosis is poor for resolving otitis with medical therapy alone, and surgery (total ear canal ablation with bulla osteotomy) is indicated. The absence of fluid in the middle ear or bony changes in the tympanic bulla does not rule out the possibility of otitis media.

Treating Pseudomonas otitis

The two most critical elements of treating Pseudomonas otitis are: 1) keeping the ear clean, and 2) administering antimicrobial therapy.

In addition, in chronic otitis cases with swelling and inflammation of the ear canal epithelium (leading to canal stenosis), it's vital to reduce swelling and open the ear canal. Swollen and stenotic external ear canals prevent canal and tympanic membrane evaluation, ear canal cleaning, and antimicrobial agent application.

Cleaning the ear of debris and exudate is important for several reasons, including the following:

  • It removes the nidus for reinfection.
  • It removes bacterial and inflammatory debris.
  • It allows antimicrobial agents to penetrate the entire ear canal.
  • It prevents purulent debris from inactivating some antimicrobial agents.

If otitis media is present, a deep ear flush under general anesthesia is essential. Veterinarians can flush the middle ear with a 3-F tomcat catheter or 5-F urinary catheter after collecting swab specimens for cytology and culture. (You may need to perform a myringotomy first if the tympanic membrane is intact.) Flushing may need to be repeated one to two weeks later if home cleaning does not control exudate accumulation.

In chronic otitis cases with substantial swelling, hyperplasia, and inflammation leading to stenosis of the ear canal, effective ear cleaning (in the clinic or at home) can be achieved only after reducing the swelling and inflammation and opening the ear canal.

Owners should also be taught proper ear-cleaning techniques. After filling the ear canal with the cleanser, an owner should gently massage the vertical canal for as long as possible—preferably one minute—while preventing the dog from shaking its head. Otherwise, much of the cleanser will be lost prematurely through head shaking. If necessary, the process can be repeated immediately.

Owners can use cotton balls to wipe away excess cleanser around the external ear canal opening. They should not put cotton swabs or cotton balls inside the ear canal because this could cause trauma, including epithelium maceration or debris impaction.

In acute otitis cases, owners should clean the affected ears every 24 to 72 hours, depending on the degree of exudate accumulation. For chronic otitis or cases where otitis media is present, they should clean the ears daily.

For Pseudomonas otitis, I use either Epi-Otic (Virbac) or an acid-based cleaner, such as OtiRinse (DVM Pharmaceuticals), Oti-Clens (Pfizer), or MalAcetic Otic (DermaPet). Epi-Otic has been shown to have considerable antimicrobial activity both in vitro5 and in vivo. In one study, flushing the ears twice daily with Epi-Otic alone resolved Pseudomonas otitis within two weeks in four dogs.6

Antimicrobial therapy

Table 1: Antibiotics with Potential Activity Against Pseudomonas Aeruginosa
P. aeruginosa is often resistant to multiple antimicrobial agents. Successful treatment depends on selecting appropriate antibiotics for aggressive topical and systemic administration. Table 1 lists the antibiotics that may be used to treat P. aeruginosa infections.


Source: Clinical Edge,
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