The presence of excess wax and moisture in the ear predisposes to a fungus infection. This is a common cause of extenal otitis. Secondary fungus or yeast infections frequently occur when long-standing ear infections are treated with antibiotics.
     Signs and symptoms are not nearly so pronounced as when the infection is caused by a bacteria. The ear is less inflamed and less painful. The discharge usually is dark, thick, waxy, but not purulent. A rancid odor is characteristic.
     The treatment is similar to bacterial infections, except that an antifungal agent (nystatin) is used to medicate the ears. Panalog or Tresderm, which contain nystatin, can be used. Yeast and fungal infections tend to recur. Their treatment usually is prolonged.

     This disease is caused by tiny bugs that live in the ear canals and feed on skin debris. Mites are the most common cause of an ear infection in a puppy or young dog. Suspect it whenever both of your dog's ears are infected.
     The characteristic sign is intense itching (i.e., scratching and violent shading of the head) The ear discahrge is reddish brown, or black and waxy, sometimes resembling that of a yeast or fungus infection. To mek the diagnosis, remove some ear wax with a cotton swab and look at it under a microscope against a dark background. Mites are white specks, about the size of the head of a pin, that move.
     At times ear mites leave the ear canals and travel out over the body. They are highly contagious to dogs and cats. If there are other pets in the household, they should be treated.
     Treatment: Do not begin treatment until you have identified the mites. Other ear problems can be complicated by using an ear-mite preparation.
     Clean the ears . Medicate the ears with a miticide twice weekly for three full weeks. As the medication does not destroy eggs, a new crop of mites will reinfect your dog if you stop too soon.
     An antibiotic is given if the ear problem is complicated by bacterial infection. Ear preparations containing a miticide, an antibiotic and a steroid (to reduce itching) are available. They include Cerumite, Canex and Tresderm.

      This disease is first noticed along the edges of the ears on smooth coated chihuahuas. It first appears as hair missing just along the edges and tips of the ears. It is usually followed by a thin crusty scab that peals in layers off the ears. While it is called a fungus it is really caused from the dog getting a chill and the skin cells dying off along the edges of the ear.
       Treatment:  First apply a thin coat of an oil preparation such as baby oil, mineral oil, or vaseline. Leave it on for at least 24 hours. The thin scabs can then be peeled safely from the ear. An antibiotic salve or lotion should be applied to the new layer of skin to make sure there are no secondary infections.