Common Causes of Dog Ear Infections

Sep
15
2009

The Anatomy of the Canine Ear

A dogs ears are the same as a persons ears in that their main function is hearing. Dog ears just do not look like peoples ears. The outside part of the ear is called the pinna. In some dogs it is floppy (like a Basset Hound) and in some dogs it stands up (like a Corgi). The pinna helps to funnel sound into the ear canal. Whereas people have a straight ear canal, the ear canal in the dog is a little L shaped. It is made up of the vertical (descending) canal and the horizontal canal. The horizontal canal ends at the eardrum, or tympanic membrane. The eardrum is a transparent membrane that separates the external ear from the middle and inner ear.

The most common is an infection of the outside of the ear including the horizontal and vertical canals. This infection is referred to as Otitis Externa and is caused by three main reasons; ear mites, bacteria and yeast.

Ear Mites or Otodectes cynotis cause these ear infections. While they are most commonly found in puppies, any dog at any age can get them. They are contracted by exposure to other animals infected with them and can live on the head and neck as well.

Malassezia is the most common cause of a yeast related ear infection while Staphylococcus is the most seen factor in bacteria related ear infections. These two forms are generally more common than ear mite infections; however there are predisposing factors that can make your dog vulnerable. These factors include:

Malformed Ear Canal – When a dogs ear canal is too long or too small, this provides ample opportunity for moisture and debris to become trapped leading to an infection.

Over Abundance of Hair in the Canal – This excess amount of hair is the perfect tool for trapping debris and holding onto water which can lead to an infection.

Swimming and Humid Areas – If a dog loves to swim, he/she can have water trapped in the horizontal and vertical canals which leads to infection. In addition, if a dog resides in a humid climate, the ear can retain moisture from the air, thus resulting in an infection.

Floppy or Folded Over Ears – Pinnae that cover the vertical canal can trap debris and retain water which results in ear infection.

Food allergies – An allergic response to a particular food ingredient can change the environment of the ear canal leading to moisture build-up and an ear infection. Dogs with food allergies may have other skin problems, too.

Seasonal or Inhalant allergies (atopy) – An allergic response to grass, trees, mold, dust, etc. can change the environment of the ear canal leading to moisture build-up and an ear infection. Dogs with seasonal allergies will usually have other skin problems, too.

Systemic Diseases – Diseases that affect the endocrine system such as hypothyroidism can affect the skin and the immune system. When both of these systems are compromised, an ear infection can occur.

A growth or foreign object in the ear – A growth or foreign object in the ear can trap water and debris in the ear canal leading to an infection.

Cleaning the ears too much and leaving water or cleanser in the ears may also predispose a dog to getting ear infections.

Heather Fox is an experience veterinarian who loves to share her knowledge about Dog Illness Diagnosis. She has an online classroom at Clivir.com where you can find more of her articles about Ear Infections in Dogs.