Pseudomonas aeruginosa otitis externa in dogs treated under general anesthesia with a 20 minutes ear flush of Tris EDTA and Chlorhexidine followed by a Ciprofloxacin medication
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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.