| dc.description.abstract | Otitis externa is a multifactorial syndrome characterized by skin inflammation in the
exterior ear canal. It represents around 10% of canine veterinary consultations. The primary
factors initiating the otitis externa, which must be ruled out when the condition is recurring,
may be allergies, parasites or foreign bodies in the ear canal, endocrine disturbances and
autoimmune diseases. Moreover, some dogs are predisposed to developing otitis externa.
Animals with pendulous ears, hypertrichosis in the ear canal, or the ones which frequently bath
and thus with high humidity in the ears, will tend to suffer from otitis externa most often than
the others. In addition, the pathogens found in the otitic ears are perpetuating factors, further
worsening the condition. The organisms most often found in infected ears are Staphylococcus
spp, Streptococcus spp, Malassezia spp and Pseudomonas spp. Otitis externa caused by
Pseudomonas aeruginosa is characterized with acute suppurative exudate, severe
inflammation, ulceration, discomfort and pain. Several different options may be chosen by the
veterinarians in order to treat otitis externa. Topical therapy is an important part of the treatment.
However, Pseudomonas aeruginosa is found to be often resistant to most commonly used
antibiotics and readily acquires new resistance. In fact, the capsulated bacteria is able to inhibit
the accumulation of antimicrobials as well as promote their inactivation. This is due to the
restricted permeability of the bacterial cell wall and to the enhanced alterations it causes in the
target molecules. Pseudomonas spp are additionally able to form a biofilm thought to be an
important virulence and protective factor of the bacteria. Because of the issue of resistance and
recurrence, some veterinarians resort to the use of systemic antibiotics. Eventually, surgery is
sometimes required in end stage otitis externa.
Choosing the proper ear cleaners and antibiotics is crucial to be able to treat the
Pseudomonas spp otitis externa. The objective of this study is to demonstrate a better recovery
rate of otitis caused by Pseudomonas aeruginosa than found in other studies, when cleaning the
infected ear under general anesthesia with a 20 minutes ear flush together with tris EDTA and
chlorhexidine; completing the treatment with a ciprofloxacin therapy.
A total of 31 dogs were accepted in the experiment. A scoring system was used to rate
the severity of their otitis and samples were sent to the cytology and microbiology laboratories
to ensure the presence of Pseudomonas aeruginosa. This experiment confirms some breeds’
predisposition to otitis externa. Also, it agrees with how Pseudomonas spp otitis’ microflora
and clinical signs are described in the literature. In addition, it demonstrates promising results
for the experimental treatment with a good recovery rate and short treatment duration. Further
sampling should however be performed to be able to be more conclusive, as only 5 dogs could
receive this treatment. Finally, it shows the limits of cytology and microbiology’s reliability. | en |
