Ear Care and Disease in the Dog

"My dog's ears have a terrible odor. What could it be?" "My puppy has been scratching his ears. The ears have dark, crumbly material in them. What should I do?" "My dog has been rubbing his ears on the carpet, but I do not see anything wrong. Why is he doing this?" These are some of the most commonly asked questions of veterinarians.

Signs of ear disease

Every day we see dogs who have problems with their ears. Signs of these ear problems include:

Odor
Scratching or rubbing of ears and head
Discharge in the ears
Redness or swelling of the ear flap or canal
Shaking of the head or tilting it to one side
Pain around the ears
Changes in behavior such as depression or irritability

Ear disease is one of the most common conditions we see in pets. The medical name for inflammation of the outer ear canal is 'otitis externa.' It is estimated that up to 20% of the dog population is affected by this disease.

Causes of ear disease

Dogs can have ear problems for many different reasons. When we see a dog with ear disease we need to think about the possibility of:

Allergies such as atopy or food allergies
Parasites - ear mites
Microorganisms - bacteria and yeast
Foreign bodies, e.g., plant awns
Trauma
Hormonal abnormalities, e.g., hypothyroidism
The ear environment, e.g., excess moisture and ear anatomy
Hereditary or immune conditions, and tumors

Allergies: Dogs with allergies, either to food or something they inhale, often have ear problems. As a matter of fact, the ear problem may be the first sign of the allergy. Since the allergy changes the environment within the ear, we sometimes see secondary infections with bacteria or yeast. If we just treat the infection, we are not getting to the root of the problem. We need to treat the allergies too.

Parasites: The ear mite, Otodectes cynotis, is a common cause of ear problems in cats, but less common in dogs. Some dogs are hypersensitive to the mites, however, and the resultant itching can be intense. These dogs may scratch so much they severely traumatize the ear.

Bacteria and Yeast: Numerous types of bacteria and the yeast, Malassezia pachydermatis, cause ear infections. The normal, healthy ear has a good defense against these organisms, but if the ear environment changes due to allergies, hormone abnormalities, or moisture, the bacteria and yeast can greatly multiply and break down these defenses.

Foreign Bodies: Plant awns, those little "stick-tights" that cling to our clothes and our dogs' fur, can sometimes enter the ear canal. Their presence causes irritation, the dog scratches, and before you know it we have a traumatized, infected ear So when you groom your dog after a walk in the woods, be sure to check the ears, too.

Trauma: As we described above, self-inflicted trauma to the ear due to scratching can exacerbate ear problems.

Hormonal Abnormalities: Deficiencies or excesses of various hormones can result in skin and ear problems. Thyroid hormone, glucocorticoids produced by the adrenal gland, and sex hormones all influence the health of the skin and ears.

Ear Environment: Bacteria and yeast could not ask for a better environment to live in than a warm, dark, moist ear canal. Dogs with heavy, floppy ears such as Cocker Spaniels may have ear problems due to the excess moisture that builds up in their ears.

Other Causes: There are various rare hereditary diseases that occur in different breeds or lines and affect the ears. These include dermatomyositis in Collies and Shetland Sheepdogs, and primary seborrhea in Shar Peis and West Highland White Terriers. Squamous cell carcinomas, melanomas, and other tumors can be seen in the ears.

Diagnosis

Because there are many potential causes of ear problems, we cannot just say it is a bacterial infection, dispense antibiotics, and it will go away. Often, more work is needed. Your veterinarian can use an otoscope to look down into the ear canal and determine the amount of inflammation present, if the tympanic membrane (ear drum) is involved, and if there are any foreign bodies, tumors, or other potential causes of the problem. Swabs of the ear can be taken, smeared on a microscope slide, stained, and examined for bacteria, yeast, and mites. A thorough history and physical exam may help determine if this could be a hormonal, allergic, or hereditary problem. If these are suspected, further diagnostic testing would be needed. If a bacterial infection does not respond to the first antibiotic therapy, a culture and sensitivity may need to be performed to select a different antibiotic. Continue reading...