A dog's ear canals are much longer and more L-shaped than humans. Much like the plumbing elbow underneath the kitchen sink, dog ears are the perfect place for debris and microbes to gather. Ear canals are often wet and warm, and when filled with microbes — bacteria, fungi, ear mites or yeast — they are the perfect environments for infection.

How do you know if your dog has an ear infection?

"Pet owners often complain about a foul odor coming from their pet's ears," says Dr. Mary Bryant, a small-animal veterinarian from Delaware. "Or, they'll notice their pet scratching at their ears or shaking their heads."

According to veterinary dermatologist Dr. Steve Melman, allergies with secondary infections are the No. 1 cause of otitis (inflammation of the ear), with Malassezia/yeast as the culprit 90 percent of the time.

"Malassezia otitis often looks like a dark, waxy discharge and will respond to cleaning with MalAcetic Otic (DermaPet) once daily for a week," says Melman. "But to prevent recurrence, the underlying cause must be discovered and treated."

Some cases progress to a much more severe form of bacterial otitis, i.e., Pseudomonas otitis. This ear infection is more difficult to treat, requiring a veterinary cleaning with a tris-edta solution followed by 12 weeks of prescribed oral and topical antibiotics.

According to the American Animal Hospital Association, the two most common types of ear infection are: otitis externa, an infection of the external ear canal; and otitis media, infection of the middle ear.

Other causes of ear problems include tumors, ear mites, fly strike, hair buildup, food sensitivities and even metabolic disorders of the ear canal lining.

Retrievers, spaniels and hounds with pendulous ears that hang down covering the ear opening; dogs with narrow ear canals; and dogs with hairy inner ear flaps that prevent air from entering the ears to dry them out, such as poodles and schnauzers, are more prone to ear infections.

Left untreated, dirty ears can cause chronic infections that are resistant to normal medications. Vigorous shaking of the head can also break the earflap cartilage, causing painful blood clots, called hematomas, that must be drained or surgically corrected. The worst-case scenario is an inner-ear loss of balance and/or permanent hearing loss.

Prevention is the best medicine. For dogs with long, floppy ears, such as basset hounds, you can use tall, narrow dishes designed to keep earflap tips from daily exposure to moisture that puts ears in harm's way. Dogs with a history of ear problems will benefit from professional grooming to remove the hair blocking airflow to the inner ear.

With recurrent ear problems, your veterinarian will likely recommend a regular program of professional grooming, cleaning the ears and keeping them dry.

Ear infections can be painful, so dogs may associate treatment routines with this pain. "Remember that most dogs don't know we are cleaning their ears for their own good. Help the dog to accept this healthcare by coupling ear cleanings with food treats and praise for good behavior," recommends Dr. Rolan Tripp, founder of www.AnimalBehavior.Net.

"Talk in a soothing voice and give tasty rewards before, during and after the ears are cleaned or treated. Some dogs may even look forward to this type of ear preventive care."

To clean the ear canal, pull the earflap, or pinna, straight out from the head at almost a 90-degree angle. That pulls the L-shaped ear canal into a straight line, allowing the ear cleaning solution to reach the entire ear. For this step, your veterinarian will recommend an ear-cleaning product that dissolves wax and debris buildup gently but thoroughly and is easy on the surrounding tissues.

Once the cleaning solution has filled the ear canal, massage the base of the ear with your fingers for about 15 seconds. Some veterinarians recommend the careful use of a bulb syringe (it looks like small turkey baster) to flush the ear. Either way, the agitation action helps the cleaning solution to penetrate deeply and cover all of the surfaces of the inner ear.

After this cleaning, allow your dog to shake his or her head to get rid of the excess solution. Then, using a small, thin cloth or a gauze sponge wrapped around your index fingertip, probe into the outer part of the ear canal to gently wipe away the wax and debris that the ear cleaner has loosened. Do NOT use a Q-Tip to go any further than you can see, since it is possible to go too deep and break the eardrum! The next step is a treatment solution that stays in the ears.

Get in the habit of smelling your dog's ears for the first sign of a rank odor, one indication of a budding infection. In chronic cases, your veterinarian may recommend using a preventive ear medicine in the ears after every bath, since water often triggers infections in dogs prone to ear problems. For these dogs, your veterinarian may also recommend a drying agent as a routine preventive treatment to keep bacteria at bay.

If your dog acts deaf when you call him or pretends he can't hear you when you are only steps away, a simple test may tell you if your pooch's hearing is still keen. Open a can of dog food, rustle a package of his favorite treats or rattle his leash, and see what happens! If in doubt, have your veterinarian perform a thorough ear exam.