When dogs have ear infections, they tend not only to scratch their ears but also to shake and tilt their heads. If it’s a yeast infection, you’ll probably notice a foul odor emanating from the infected ear as well.
A veterinarian can confirm whether your dog has a yeast infection by swabbing his ear and having a lab technician view the sample under a microscope. Because yeast is present even in a healthy ear, there will need to be a higher-than-normal amount of it present to indicate an infection.
In some cases, it may be difficult for your veterinarian to confidently determine the presence of a yeast infection by laboratory examination alone. However, he or she may treat it as such if the symptoms point that way. If the malady responds to medical care, the yeast infection diagnosis is definitive. If, however, your dog continues to have problems with her ear despite treatment, your veterinarian will explore other potential causes.