If you are a dog lover, chances are one of your canine companions has experienced an ear infection. No fun, right? And if your dog has suffered with recurrent ear infections, chances are you’ve felt like pulling your own hair out!
The following information is intended to enhance your understanding of the canine ear and help you get the help you need if your dog develops ear issues.
The anatomy of the canine ear canal
I invite you to join me on an imaginary trip. Pretend you are miniaturized to the size of Tom Thumb. Now slip beneath your dog’s earflap and sit yourself down on the ledge of the opening to the ear canal. Give yourself a little push-off and then let gravity launch you down what feels like a giant slip and slide. Here is what you will see along the way.
The first part of your voyage is within the vertical ear canal, aptly named because of its rather steep descent. You are sliding down a wide-open tunnel with smooth pink surfaces. You come to an abrupt halt as you arrive at a rather sharp bend within the tunnel. You stand and take a few short steps that bring you to another descent, this one more gradual. You are now within the horizontal portion of the external ear canal. Looking forward you see a glistening, semi-transparent membrane that fills the entirety of the tunnel ahead. Aha! This must be the eardrum (tympanic membrane). It appears quite thin so you muster up some speed and run straight towards it. Your force and momentum cause the eardrum to rupture and you topple forward into a large cavernous space.
The middle ear
You’ve now entered the tympanic bulla (middle ear cavity), an open and empty, smooth surfaced cave created out of bone. It’s not easy, but you manage to climb out of this cavern, and as you approach the top you notice multiple small bones (ossicles that are responsible for transmitting sound) along with what looks like a thin window shade called the cochlear window. You poke your head through the shade and find yourself peering into yet another space. Bold little traveler that you are, you climb on in.
The inner ear
You have entered the inner ear a rather small and crowded space filled with some really crazy looking labyrinthine structures. Some of them are responsible for transmission of sound to the brain, others for maintenance of balance. You see a white ropy structure that is a nerve leading directly into the brain. Now wait just a minute before you grab hold of that nerve! I think you’ve done enough for one day!
What you’ve observed
Exhausted as you are after your incredible journey you’ve likely gained some new knowledge about the canine ear:
From the surface, the ear may look like a pretty simple body part. In fact, what lies beneath is an amazingly complex structure consisting of the external ear canal, the middle ear, and the inner ear.
The normal external ear canal appears wide open, smooth-surfaced, and devoid of any fluid or debris.
The eardrum is quite thin and fragile. It can be fairly easily perforated by a foreign body within the ear canal or in response to infection.
Following swimming or bathing moisture is readily retained within the external ear canal, thanks to gravity and the anatomy of the ear canal. Such moisture predisposes to ear infections (more information about this next week). The same holds true for foreign bodies. Once they’ve entered the external ear canal they typically stay put, even with vigorous head shaking.
The length and structure of the external ear canal make it impossible to be viewed in its entirety without the use of a special instrument called an otoscope. An ear problem in a head-shaking dog cannot be ruled out with an at-home flashlight exam!
Stay tuned for part two of this blog post in which I will discuss a variety of canine ear diseases, their causes, and treatments.
Did you learn anything new on your “incredible voyage”? Leave us a Comment and Stay Tuned for Part 2 and 3 of the Series on Canine Ear Health By Dr. Kay
Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Spot’s Blog: http://www.speakingforspot.com/blog