Objective—To evaluate differences in bacterial numbers,
identity, and susceptibility in samples obtained
from the tympanic cavity on entry (preflush) and after
evacuation and lavage (postflush) and assess perioperative
and empiric antimicrobial selection in dogs
that underwent total ear canal ablation (TECA) with
lateral bulla osteotomy (LBO) or reoperation LBO.
Design—Prospective clinical study.
Procedure—TECA with LBO or reoperation LBO was
performed on 47 ears. Pre- and postflush aerobic and
anaerobic samples were obtained from the tympanic
cavity. Isolates and antimicrobial susceptibility patterns
Results—Different isolates (31/44 [70%] ears) and susceptibility
patterns of isolate pairs (6/44 [14%] ears)
were detected in pre- and postflush samples from
84% of ears. Evacuation and lavage of the tympanic
cavity decreased the number of bacterial isolates by
33%. In 26% of ears, bacteria were isolated from postflush
samples but not preflush samples. Only 26% of
isolates tested were susceptible to cefazolin. At least 1
isolate from 53% of dogs that received empirically chosen
antimicrobials postoperatively was resistant to the
selected drugs. Anaerobic bacteria were recovered
from 6 ears.
Conclusions and Clinical Relevance—Accurate
microbiologic assessment of the tympanic cavity
should be the basis for selection of antimicrobials in
dogs undergoing TECA with LBO. Bacteria remain in
the tympanic cavity after evacuation and lavage.
Cefazolin was a poor choice for dogs that underwent
TECA with LBO, as judged on the basis of culture and
susceptibility testing results. (J Am Vet Med Assoc 2005;227:748–755)