Inflamed Ear Canals Can Have Many Causes
An inflammation of the ear canal is called otitis. Most lay people call this an ear infection, and many times, an infectious microbial agent is involved, but occasionally the root of the problem is something other than a primary infection.
Dog and cat ears are built a little differently than human ears, but the variations are fairly minor. The ear flap is called the pinna. Below that is the canal leading to the eardrum, or tympanum.
Cat pinnae are fairly uniform from cat to cat and breed to breed. They are triangular and stand upright in almost all cats. Some purebred cats will have a distinct fold in the pinna that causes the flap to lie flat against the head and cover the ear canal. These cats are relatively rare and most of the time a cat with a folded ear will have suffered some injury that has healed poorly.
Dogs, of course, have a variety of ear shapes and sizes. We see upright pinna as in the German shepherd. These often are called “prick” ears. Herding breeds often have ears that are upright at the base but fold forward toward the tip. This is called “semi-prick.” Lassie was a great example.
Beagle, bassets and many other breeds have droop ears. As a general rule, dogs with droop ears tend to have more problems than dogs with more upright pinna.
Inflammation of the pinna is a different problem than true otitis. Dogs and cats come in with problems that involve only the pinna from a variety of causes. White cats, in particular, present with skin cancer at the margins of their pinnae. Occasionally an artery within the pinna will rupture and the pinna will fill with blood. This problem requires professional attention to heal well.
Inflammation of the canal is much more common than an inflammation of the pinna. This inflammation will cause the pet to shake its head or paw at the ear. This often is the first symptom that owners notice.
The cause of the inflamed canal may be a simple infection. Often there is some other underlying problem that let the infection get a foothold. Veterinarians often find foreign bodies, such as weed seeds or small twigs, in ears. Many breeds of dogs grow hair in the ear canals, and sometimes upon exam, the canal will be filled with wax and hair. Other breeds will form wax plugs devoid of any hair.
Ear mites are common in kittens and young outdoor cats but relatively uncommon in older cats, indoor cats and dogs. Ear mites are actually eight-legged creatures that resemble tiny ticks living in the ear canal. They are not visible to the naked eye, but are spectacular under low power magnification. Dogs with ear mites usually get them from the household cat. The mites appear to not be terribly contagious, and the affected dog has to spend considerable time resting with the cat to contract them.
Both bacteria and yeast also can infect ears under the right conditions. They result is a reddened and sore ear canal with debris that ranges from gray liquid to red-brown wax. A sample of the debris often is examined under a microscope to determine microbe or variety of microbes present. At that point, an effective drug can solve the problem. Occasionally, an oral antibiotic is used, but usually treating ear infections means some sort of topical medication.
If ear infections become recurrent, there is usually some underlying problem. Allergies, either to food or inhaled irritants (pollens or molds, cigarette smoke, dust mites), can result in recurring ear problems. Conformation problems or metabolic disease can result in recurring infections.