Ear Infections (Otitis)
A number of medical problems related to ears can affect Flat-Coated Retrievers including ear infections. There are many causes of ear infections. The following description of ear anatomy may help you better understand why ear infections are so common in the dog.
The ear is divided into three parts. The outer ear consists of the earflap (pinna) and the ear canal itself. An infection of this outer ear is termed otitis externa. The middle ear contains the eardrum (tympanic membrane) and the tiny auditory bones that lie just behind it. An infection of the middle ear is called otitis media. The inner ear consists of sensory structures that are lined with tiny hairs (cilia). These structures convert sound impulses from the middle ear into electrical impulses that then travel along the auditory nerve to the brain. These structures are also responsible for maintaining the overall balance of the dog. Infection here is termed otitis interna.
The ear canal is structured in such a way that it commonly is affected by infectious processes. In our breed, it is about two inches in total length with an upper diameter similar to that of a pencil. It begins at the outer ear and travels downward. Along the way, it changes its direction and becomes horizontal. This two-directional anatomy serves to protect the eardrum from injury, but also predisposes to wax, water and dirt collection at its base. Pendulous earflaps seal the vertical canal to create a warm, moist environment without much airflow. A variety of organisms find this a perfect location for growth. These include bacteria, yeast and fungi and mites.
Outer ear infections are very common. Middle and inner ear infections are less common. These can result from an outer ear infection that has progressed to the middle or inner ear. They are difficult to diagnose because they are often accompanied by outer ear infections. The dog whose middle or inner ear is involved may be in extreme pain. It may also appear dizzy, uncoordinated and vomit. Veterinary care is imperative for these dogs.
Additional predisposing factors for ear infections include:
- Excessive ear hair
- Hanging floppy ears
- Water left in the ears after swimming or bathing
- Ticks, fleas, ear mites
- Abnormal thyroid gland function
- Skin conditions such as seborrhea
- Head and ear shaking
- Scratching at the ears
- Foul odor
- Ear flap redness
- Ear discharge
- Pain when ears are touched
- Hearing loss
Diagnosis begins with a simple otoscopic examination by your veterinarian. During this examination, the veterinarian will be looking for foreign objects that may have entered the canal, presence of fleas, ticks or mites, and quantity and color of ear discharge. A sample of the ear discharge may then be viewed under a microscope to determine if it contains bacteria, white blood cells, yeast, fungi, ear mites or ear mite eggs. Although this exam is simple, there may be dogs that are intolerant of the procedure due to the pain involved. These dogs may require general anesthesia. Your veterinarian may also decide to perform bacterial or fungal cultures of the debris removed from the ear. This is done to determine the specific organism responsible for the infection and which anti-invective drugs will be useful in treatment. For dogs with chronic ear infections, further diagnostic work-up may be suggested. This may include skull x-rays, thyroid function tests and intradermal skin testing or serum RAST testing to determine if allergies are present.
Treatment should address known underlying causes. This may include:
- Removal of foreign objects such as vegetation, seeds, sticks and dirt.
- Flushing to remove impacted ear wax.
- Treatment for thyroid dysfunction.
- Avoidance of allergens.
- Parasite control
Basic treatment will also involve application of antibiotic and/or anti-fungal ear ointments or drops as prescribed by your veterinarian. Most contain a cortisone-like drug as well. If ear mites are found, other medications are required.
Regardless of the type of medication, it is important to follow your veterinarian's treatment plan carefully. Stopping treatment prematurely because symptoms have abated may allow a few remaining organisms to repopulate. This will result in another ear infection and these organisms may now be resistant (not affected by) to the same antibiotics. A good rule is to seek veterinarian advice whenever treatment does not lead to improvement in several days.
For dogs who develop chronic ear infections for which no underlying cause can be determined or have excessive scar tissue, your veterinarian may suggest surgery. This changes the shape and size of the canal in order to provide better drainage and exposure to the air.
To minimize the occurrence of ear infection, your veterinarian may suggest a cleansing agent to be used at least weekly. These solutions dissolve ear wax and dry the ear canal. This produces an environment less favorable to growth of organisms. Be sure to perform this routine ear care after your dog has been swimming or has been bathed. You may also want to clip excess hair from around the ear canal opening. Carefully inspect the ears of dogs who have been out in a field environment for foreign objects such as grasses or weeds that may have entered the ear canal.
MODE OF INHERITANCE:
Unless ear infections can be traced to hypothyroidism as the cause, ear infections are not genetically transmissible.
Bailey, C. S. The nervous system and disorders. In Siegal, M., ed. UC Davis school of veterinary medicine book of dogs: a complete medical reference for dogs and puppies. New York: Harper Collins, 1995; 282.
Foster, R., Smith, M. What's the diagnosis? New York: Howell Book House, 1995;.193, 196-199.
Ihrke, P.J., Barlough, J.E. The skin and disorders. In: Siegal, M., ed. UC Davis school of veterinary medicine book of dogs: a complete medical reference for dogs and puppies. New York: Harper Collins, 1995; 227.
Wilson, J. F. The ear and disorders. In: Siegal, M., ed. UC Davis school of veterinary medicine book of dogs: a complete medical reference for dogs and puppies. New York: Harper Collins, 1995; 194-196.