Disorders of the Outer Ear in Dogs

There are a number of skin disorders that may travel to the ears and many infections and infestations that are common to the outer and inner ear canal. Disorders that primarily affect the pinna, or the outer portion of the ear, are fewer, but no less distressing to your pet. They can cause painful swellings, lesions, and be incredibly itchy. Although many of these may heal on their own, veterinary attention will help to prevent permanent scarring and further infestation and infection, as well as to reveal any underlying causes.

Disorders of the outer ear, clinically known as the pinna, including auricular chondritis, ear hematomas, and fly strike, can be distressing and disfiguring without proper treatment.

Many of the symptoms of these pinna disorders are similar. Any of these disorders could produce symptoms of:  

• Ear is hot to the touch
• Head shaking
• Painful ears
• Redness of the ear
• Scratching at the ear
• Swelling of the pinna

Although each of these disorders changes the appearance and texture of the outer ear, the way that they do so is more divergent.

Types

Auricular chondritis - This rare disorder generally affects both ears and causes swelling and deformity in the ear due to visible lesions as well as a loss or necrosis of cartilage in the ear. Although treatment can halt the progress of this disorder, damage that has already occurred cannot be reversed.

Ear hematoma - Fluid or blood-filled swellings that form on the inside surface of the dog’s pinna. If it is only affecting one ear, the dog may hold its head cocked to one side, and in some cases, the entire ear becomes swollen.

Fly Strike - This disorder is caused by fly bites on the ears. A common problem for both horses and dogs, it results in painful bleeding sores along the edges and the tips of the ear. Flies may also lay eggs in these wounds, causing an infestation by maggots called Myiasis when the eggs hatch.

The cause for auricular chondritis is not well understood although trauma to the ear may play a small part. Although reasons for a similar disease in humans appears to have a link to immune-mediated disease, this cause is not supported in dogs and cats. 

Hematoma in the ear is mostly related to the physical agitation of the tissues. Scratching of the ear, damage due to rough play, bites of fleas or mites, or even excessive head shaking can lead to a broken blood vessel in the ear and the formation of an aural hematoma. 

Fly strike is caused by the bite of a fly. The fly most likely to cause this kind of damage is the common stable fly, but other types of flies, such as deerflies, blackflies, and even the housefly, can bite the ears as well. The flies most likely to lay their eggs in open wounds are the bluebottle and the bow fly.

When you bring your dog into the veterinary clinic, any open wounds or lesions found on the ear will be thoroughly cleaned and evaluated for infestation, infection, or necrosis. 

Ear hematomas and auricular chondritis are generally quite easy to diagnose with a physical examination of the area. However, if there is an underlying cause, this cause may be more challenging to deduce and treat. Dogs that continually itch their ears or shake their heads may be responding to disorders such as ear infections, foreign bodies, or wax buildup, so the ear canal will be thoroughly examined. This allows your dog’s doctor to either rule out or treat these disorders so that the hematoma is less likely to reoccur. Once the hematoma itself has been successfully drained, the testing will be similar to the testing for other troubles of the outer ear. 

In order to determine if any of these conditions are being instigated or aggravated by any sort of bacterial or fungal infection a sample of the affected area will need to be carefully examined, usually by examining it under a microscope. Fleas or mites may also be found in the sample, and the bites of fleas and mites can lead to hematomas of the pinna by causing severe itching.

As the cause of auricular chondritis often remains hidden, treatments focus on treating any lesions and removing any necrotic tissues. An antibacterial medication by the name of dapsone may also be prescribed as it has had some luck in halting further damage to the cartilage.  

The lesions and bumps from fly strike will be cleaned and meticulously inspected to ensure there are no necrotic tissues, maggots or fly eggs, or infections. This process can be painful and your dog may require sedation or anesthesia depending on the extent of the damage. Liquid antibiotics may be administered directly to the ears and a systemic antibiotic may be prescribed to promote healing. 

Hematomas of the ear should be drained by a veterinary professional to prevent scarring and infection. In some cases this can be done by using a hypodermic needle to draw out the blood, or small incisions may be made in the ear to allow drainage. In severe cases, your veterinarian may choose to make a larger surgical incision in order to drain the wound, and then stitch it back up. Once the wound has been drained, soft drain pipes are sometimes left in the ear in order to prevent further buildup of fluid.

These disorders often are accompanied by open wounds, sometimes for quite a while after successful treatment. It is critical to ensure that these wounds remain clean and free of debris while they are healing. Your dog should be prevented from licking, chewing, or scratching at their ears during recovery. In some cases, use of a Victorian collar may be required to remove temptation. Administer all of the topical and oral medications as prescribed, even if the wounds do not appear to be infected. Discontinuing antibiotics early may result in a reoccurrence of any bacterial infections or induce more resistant bacteria to develop.