Disorders of the outer ear

Disorders of the Outer Ear in Dogs
By T. Mark Neer, DVM, DACVIM, Professor and Hospital Director, Center for Veterinary Health Sciences, Oklahoma State University ; Michele R. Rosenbaum, VMD, DACVD ; Patricia D. White, DVM, MS, DACVD

A variety of skin conditions affect the outside part of the ear, called the pinna. Most conditions cause tissue changes elsewhere as well. Rarely, a disease affects the outer ear alone or affects it first. As with all skin conditions, a diagnosis is best made when combined with the results of a thorough history, a complete physical and skin examination, and carefully selected diagnostic tests.

Insects and parasites commonly cause inflammation of the pinna—resulting in redness, swelling, itching or blistering—either through direct damage from the bite of the parasite or as a result of hypersensitivity. Tiny skin mites burrow under a dog’s skin, often on the edges of the ears. Because they are so hard to see and find, a veterinarian might take several skin scrapings before making a diagnosis.

Canine Juvenile Cellulitis
Canine juvenile cellulitis is an infection and inflammation of the tissues beneath the skin of young dogs. It is an uncommon disorder of puppies and is characterized by masses of small, round raised areas of inflamed skin filled with pus on the face and ears. The lymph nodes below the lower jaw are usually noticeably enlarged. It occurs in puppies 3 weeks to 4 months of age and rarely in older animals. Golden Retrievers, Gordon Setters, and Dachshunds appear to be at greater risk than other breeds. An inflamed, pus-filled, raised area of the skin of the ear canal is common, along with swollen, thickened pinnae. Early treatment is recommended to avoid scarring. Careful observation of the condition of your puppies will help you detect any masses or lumps on their faces or ears. Any lumps or masses, even small ones, are a good reason to take your puppy in for a checkup as soon as possible.

Ear Hematomas
Ear hematomas are fluid-filled swellings that develop on the inward curving surface of the outer ears in dogs. The cause for their development is unknown. Signs include head shaking or ear scratching due to itchiness. In dogs, the condition is seen with hereditary environmental allergies and food allergies in which the ear canals are the primary sites of allergic inflammation and itching. Treatment usually involves surgery to drain and flush the swellings. Frequently, the veterinarian will place a drain made out of a soft tube in the area to help prevent fluid from building up again.

Fly strike (irritation of the ears caused by biting flies) is a worldwide problem caused by the stable fly and typically affects dogs and horses. The fly bite causes small, hard, round bumps and raised, reddened areas with central bloody crusts that itch. Tissue changes are found on the tips or on the folded surface of the outer ears of dogs with flopped ears. Treatment includes fly repellents, controlling the fly population with environmental clean up (such as removing manure), and insecticides.

Frostbite may occur in dogs poorly adapted to cold climates and is more likely in wet or windy conditions. It typically affects body regions that are poorly insulated, including the tips of the ears. The skin may be pale or red, swollen, and painful. In severe cases, tissue death and shedding of the tips of the outer ears may follow. Treatment consists of rapid, gentle warming and supportive care. Amputation of affected regions may be required but should be delayed until the extent of living tissue is determined.

Hair Loss
Several ear edge skin disorders characterized by hair loss occur in dogs. Periodic loss of hair on the outer ear in Miniature Poodles involves the loss of hair on the outward curving surfaces of the ear. The hair loss starts suddenly and progresses over several months, but hair may spontaneously regrow. There are no other signs. Treatment is unnecessary.

Hair loss on the outer ear has been reported in Dachshunds, Chihuahuas, Italian Greyhounds, and Whippets and is thought to have a tendency to be hereditary. The age of onset is 1 year or more, when the hair coat begins to thin. Complete hair loss on the outer ear may occur by 8 to 9 years of age. Other commonly affected areas are the lower neck and chest and the back to the middle of the thighs. There are no other signs. No effective treatment has been reported, but certain drugs have been described as helpful.

Immune-mediated Diseases
Several immune-mediated diseases may affect the outer ear and the ear canal. Other areas of the body are typically affected and may include footpads, mucous membranes, skin and mucous membrane junctions, nails and nail beds, and the tip of the tail. Immune-mediated diseases are confirmed using biopsies of primary lesions.

Sarcoptic mange is an infectious skin disease caused by a parasitic mite that burrows into the top layers of the skin. It is common in dogs throughout the world. The condition begins with small, red, round bumps on the skin. These bumps progress to scaling, crusting, and raw, irritated open sores on the ear edges and other parts of the body as a result of scratching; however, in some cases only the red bumps and itching are seen. Itching is severe. Transmission of the mite is by direct contact with infected animals.

Diagnosis is based on signs, history of exposure, and discovery of mites on multiple skin scrapings. Treatment options include dips and injections. Your veterinarian will be able to prescribe the best therapy for your pet. Because mites can survive off the host for a variable amount of time, all bedding, brushes, and objects in your pet’s environment should be thoroughly cleaned.

Seborrhea and Dermatosis
Overly oily skin at the edge of the ear (seborrhea) or ear edge skin disease (dermatosis) is common in Dachshunds, although other breeds with ears that hang loose may be affected. The tips of the ears on both sides are usually affected, but the condition can progress to involve the whole ear edge. The cause is unknown. Signs include waxy gray to yellow scale sticking to the base of hair shafts. Plugs of hair can be easily pulled out, leaving behind skin with a shiny surface. In severe cases the ear edges are swollen and cracked. Treatments are available and can be prescribed by your veterinarian.

Ticks can cause irritation at the site of attachment and may be found on the pinna or in the ear canal. The ear tick, found in the southwestern United States, South and Central America, southern Africa, and India, is a soft-shelled tick whose younger, immature forms infest and live on the external ear canal of dogs and other animals. Signs of infestation include head shaking, head rubbing, or drooped ears. Both the animal and the environment should be treated. Your veterinarian can recommend the most appropriate treatment for your pet and your local area.