Source: Press Release
Hardly a day goes by that I don't see one or more dogs with ear infections. They are not common in cats. Otitis is actually inflammation of the ear pinna and/or canal. Infections are usually secondary to the inflammation.
I tell clients that the top three underlying causes of ear infections in dogs are allergies, allergies, and allergies. This may be food allergy (usually the protein source in the food) or environmental allergy (pollens, molds, etc.)
Sometimes there might be ear mites, a tumor, foreign body or hormonal disorder (hypothyroidism, Cushing's disease) associated with ear inflammation/infection, but these are uncommon when compared to allergies.
When a dog is presented with ear inflammation (shaking head, scratching or rubbing at ears, ear odor/discharge), it is necessary to not only examine the ear with an otoscope (look into the ear canal), but also look at samples of wax, discharge obtained from the canal under the microscope looking for bacteria or yeast. This allows the veterinarian to determine what type of medication is needed to treat the inflammation/infection. Your veterinarian may prescribe an ear wash to help clean the ear canal of all the wax, pus, etc. so that the medication to treat the infection will work better. Sometimes sedation is required to thoroughly clean the ear canals.
It is very important that ear infections be re-evaluated by your veterinarian after treatment to make sure the inflammation/infection is gone and to learn what you can do long-term to minimize recurrence of ear infections in your dog or cat. If ear infections are recurrent, it is important to find the underlying cause and treat it or you will become frustrated by frequent veterinary visits and treatment of an ear infection. Sometimes it recurs because the pet owner didn't follow up with their veterinarian to make sure the infection was gone.
Checking for specific underlying allergies will include feeding your pet a hypoallergenic (prescription or therapeutic diet) to rule out a food allergy. These foods should be purchased from your veterinarian or by recommendation from your veterinarian via prescription. Don't rely on any over-the-counter so-called hypoallergenic food from a pet store, etc. to reliably test for a food allergy. Food allergies are generally considered non-seasonal (the pet eats the food year round).
Environmental allergies (atopy) usually start out with seasonal signs, most commonly in pollen season (spring, summer, or fall), but with time can also become non-seasonal. If your pet's symptoms are seasonal, your vet may want to test for environmental allergies. This can be done via a blood test or skin test. Most veterinarians have access to blood testing for allergies, but most of the skin testing done for allergies are done by board-certified veterinary dermatologists. Although food allergens are included on many of the blood tests, the results aren't reliable for food allergies.
I've seen very young dogs (few months old) develop symptoms of allergies and lifelong treatment will add up to thousands of dollars. Therefore, purchase pet insurance early (ideally when young puppy or kitten before any signs occur) or it won't be covered if you later decide to get insurance.