Ear infections under the microscope

Bacteria in an ear under the microscope

Ear infections are an unfortunate secondary complication of skin disease. Occasionally they will occur due to other conditions such as ear mites, foreign bodies in the ear (such as grass seeds) or swimmer's ear, which is where some water is left in the ear canal and heats up creating a warm and moist environment.

Signs to look out for

Your pet will show his discomfort by scratching or pawing at his ear or shaking or tilting his head in the direction of the painful ear. Other symptoms to look for include:

  • Black or yellowish discharge
  • Redness or swelling of the ear flap or ear canal
  • Waxy buildup on or near the ear canal
  • Discharge from the ear that resembles coffee grounds (a symptom of ear mites)
  • Strong odour
  • Hearing loss
  • Loss of balance or disorientation.
yeast under the microscope

Under the microscope

Ears contain a small number of resident bacteria and yeast in them but when the environment of the ear changes, such as inflammation due to a skin allergy, the population of bacteria or yeast can overgrow or we can see changes in the type of bacteria seen. In order to know what type of medication we need to give to treat an infection, first we need to know what type of infection we are dealing with. Is it an overgrowth of the yeast population? An overgrowth of the normal bacterial population which consist of little round shapes called cocci or is there an overgrowth of a more aggressive bacteria which are longer called rod bacteria.

The way we determine this is via cytology which is the name of the study of cells. By putting a swab of the discharge from the ear onto a slide and looking at it under the microscope, we can see if we are dealing with yeast or bacteria and what type of bacteria. This helps us make a clinical decision as to what type of medication to use to clear up the infection.

Ear infections, left untreated, are very serious stuff.

Untreated ear infections that spread to the inner ear can result in permanent deafness, eye problems, loss of coordination and balance and facial paralysis. Therefore, we recommend you come and see one of our vets to confirm the cause and the best way to treat your pet’s ear infection.

Dr Nikki Frost BSc BVSc MANZCVS (Medicine of Cats)