Common Causes of Dog Ear Infections

September 18, 2009

in Cat Health

The Anatomy of the Canine Ear

Just as with humans, a dogs ears mainly function for hearing. The difference is the appearance. The outside part of a dogs ear is referred to as the Pinna and is sometimes floppy like a Basset Hound or straight like a Corgi. The main function of the pinna is to funnel sound into the ear canal. While human ear canals are straight, dogs are shaped like the letter “L”. The ear canal is made up of the vertical or descending canal and the horizontal canal. The latter canal ends at the eardrum or tympanic membrane. In a dogs ear the eardrum is a clear membrane and separates the external middle an inner ear.

Common Causes of Dog Ear Infections

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.

Otodectes cynotis or ear mites are the cause of this ear infection. It is most commonly found in puppies, but can be contracted at any age. It is highly contagious and is transferred from one infected animal to the next. These mites can also live on the head and neck.

The bacterium most commonly involved in ear infections is Staphylococcus and the yeast most commonly seen is Malassezia. Bacterial and yeast infections are more common in dogs than ear mite infections. Even though there are only a few causes of ear infections, many things predispose a dog to getting an ear infection. Some of the most common predisposing factors are:

Ear Canal Conformation – If a dogs ear is longer or smaller than normal, this will allow for moisture and debris to become trapped more easily, thus resulting in infection.

Excessive Ear Canal Hair – When there is too much hair in the ear canal, it tends to trap debris and retain water which leads to ear infections.

Residing in Humid Climates or Swimming – In a humid environment, water from the air can become trapped in the ear. In addition, a dog that swims can end up with water retained in both the horizontal and vertical canals, both of which can lead to infection.

Floppy or folded over pinnae – Pinnae that cover the opening of the vertical canal may result in retention of water and debris which can lead to an ear infection.

Food Allergy – When a dog is allergic to certain foods, skin reactions can occur as well as changes in the ear canal environment. When this occurs, water is retained and the ending result is an ear infection.

Seasonal or Inhalant Allergies – This is also known as Atopy. If a dog has an allergic reaction to grass, trees, mold, dust and other environmental factors it can affect the environment of the ear canal. When this occurs, moisture accumulates creating an ear infection along with skin afflictions.

Systemic Disease – Hypothyroidism or other diseases that affect the endocrine system hamper the immune systems ability to fight infection. When both of these afflictions occur, an ear infection is inevitable.

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 Diseases Symptoms. She has an online classroom at where you can find more of her articles about Dog Ear Infections Causes.

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