Hi Blaise and Erika,
I'm sorry, I realize from your feedback that I am not clearly answering your question. Your dog could possibly have (in his ear) an underlying bacterial infection which is never treated or recognized, because the secondary yeast infection is what is noticed and treated. When the yeast infection appears to be undercontrol or gone, then nothing is done to the ear. But still the bacterial infection continues. And by this bacterial infection not being treated, new yeast move in to the perfect environment created by the bacterial infection.
And (the part you were waiting for) the yeast infection can be caused by underlying allergies, bacterial infections in the ear or anywhere throughout the body and even an unhealthy immune system. However, the problem is usually right in the ear.
http://animalpetdoctor.homestead.com/Ears.html
http://www.thepetprofessor.com/articles/article.aspx?id=215
Edited by catdogcare on March 7 2006 at 8:10 PM
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