Otitis Externa is defined as inflammation of the ear canal. It is an extremely common, aggravating, and sometimes costly problem for dogs and owners alike.
This is in part due to anatomy (see below). Dogs have very long, narrow ear canals—upwards of inches long in some breeds. Halfway down is a right-angle bend that is a perfect place for debris and liquid to get stuck. Add to this the pendulous ear flaps that some breeds have (Spaniels, Beagles, Retrievers). This has the effect of sealing in warmth and moisture, giving germs a field day.
If your dog has ever had an ear infection, you know the symptoms. Head shaking, scratching, redness, brown discharge, and a sickly sweet smell are the hallmarks. Some dogs will kick relentlessly at the ear or rub it on furniture or rugs in efforts to quell the itch. Bleeding wounds can result. Depression and irritability can ensue when the itch borders on pain. Hearing can be affected. So can balance, coordination, and facial muscles in severe cases.
Ear infections usually arise from a perfect storm of factors. Primary factors are those which touch off the inflammatory process. They create moisture, heat, and stagnant air flow. They promote the perfect environment for secondary factors—yeast, bacteria, swelling and debris—to take hold. These secondary factors cause still more moisture, heat, and stagnant air to build up causing a vicious cycle of misery for your dog.
The primary causes of ear infection include:
- Anatomy Certain dogs are especially susceptible to ear infection due to their heavy, pendulous ear flaps. The ear flaps trap warm air, debris and moisture, creating a perfect environment for germs to grow. Spaniels, Basset Hounds, and Retrievers are notorious examples of flop-eared dogs prone to ear problems.
- Environment Frequent swimming, exposure to plants and pollens, time spent in wooded areas where plant awns or burrs can get lodged in the ear, or simply the humid heat of summer can set the stage for ear trouble.
- Allergies Itchy, infected ears are a classic sign of allergic skin disease in dogs. In fact otitis may be the first and only sign. What starts out as a simple ear infection often becomes a chronic problem until the underlying allergy is addressed.
- Parasites Otodectes, or ear mites, are less common in dogs than cats. Ear mites cause inflammation, copious discharge, and an intense itch that can lead to self trauma and secondary infection. Luckily they’re easy to treat with proper veterinary care.
- Foreign bodies Plant awns or plant “stickers” can get lodged in the ear and cause intense itching, scratching, and secondary infection.
- Tumors Infected tumors inside the ear trap moisture and debris and are the perfect place for germs to grow.
- Other medical conditions Hormonal imbalances such as hypothyroidism and generalized skin disorders including seborrhea, can spark inflammation that leads to otitis externa.
A raging ear infection hard to miss. But the treatment only works if both primary and secondary causes are addressed.
Your vet will first perform a full history and physical examination. Is your dog a swimmer? Been bathed recently? Is there redness, rash, or hair loss on the rest of the body, or are there other signs of generalized skin disease? What previous treatment has been tried and with what degree of success?
Next, your veterinarian will hone in on the ears. This includes an external exam of the ear flap, the ear opening and related structures, as well as a deep look into the ear canal with a special instrument called an otoscope. A painful dog may resist this exam, so it must sometimes be done under sedation. Your vet may take samples for microscopic examination or culture to identify yeast and bacteria. Xrays and biopsy may be indicated in some cases. Veterinary specialists often have high-tech fiberoptic scopes that allow even better evaluation and sample collection from the depths of a dog’s ear.
The first step in treating otitis externa is a thorough cleaning of the affected ear(s). See box, below. A deep cleaning rids the ear of secondary factors such as yeast, bacteria and debris. In mild to moderate cases, ear cleansing may be done within a routine office visit. Your vet will use a medicated ear cleansing solution along with gauze wipes or cotton balls to remove excess fluid and debris. In severe cases, your vet may recommend that an ear flush be conducted under general anesthesia. Then special probes and deep flushing equipment can be used.
Once the ear is clean and dry, topical medications are prescribed to keep the yeast and bacteria at bay. Your vet will prescribe ointments or solutions that contain a combination of antibacterial, anti-yeast and anti-itch medications. In more severe cases, oral antibiotics, antihistamines, or even oral steroids may be needed to get infection and inflammation under control.
For treatment to be successful, the primary factors need to be addressed. This may require your vet to treat for ear mites, address allergic skin disorders, or remove a tumor or foreign body. Your vet may recommend cutting back on swimming during the warm summer months, or at least following it with a good ear cleansing. Your vet may do blood work and other diagnostics to probe for underlying health issues such as hypothyroidism.
Complications and Treatment of Otitis Externa (Overview)
When ear infection continues over weeks and months, numerous complications can arise. Some are irreversible. They include:
- Chronic changes Years of infection and inflammation take their toll. Scarring and swelling causes the ear canals to close down, trapping fluid and debris worse than before. In time, the ear canals can literally solidify with hard-as-bone scar tissue. Major corrective surgery is often the only recourse at this point.
- Ear Hematoma Violent head-shaking from an intensely itchy case of otitis externa can actually injure the ear flap, breaking blood vessels below the skin surface. The result is an ear hematoma, or “pillow ear.” Ear hematoma is not painful, but should be treated promptly to reduce the chance of a disfigured ear flap. Treatment is surgical, and involves draining the fluid from the hematoma and using special sutures to tack the earflap flat again. Your veterinarian will also strive to identify and treat the itch-inducing ear problem, lest the hematoma recur.
- Middle & inner ear infection The external ear canal is separated from the middle ear cavity (see image) and inner ear (cochlea) by a thin fibrous membrane – the ear drum. Severe or ongoing otitis externa can actually rupture the eardrum. Once the eardrum is breached, it’s not long before yeast and bacteria set up shop in the area of the middle and inner ear. Symptoms of middle and inner ear may include the following:
- Tilting of the head to one side
- Poor balance
- Uneven pupils
- Strange rhythmic eye movements
- Pain on opening the mouth
- Loss of hearing
If your dog shows these symptoms, bring him your veterinarian right away.
It almost goes without saying that for ear disease, prevention is the best remedy. Cleaning your dog’s ears regularly (see below) with a gentle ear cleanser can help keep problems in check. Consult your veterinarian for detailed advice on preventing otitis externa. The itch-free comfort will be music to your dog’s ears.
How to clean ears:
- Apply a copious amount of ear cleaner directly into the ear
- Massage the base of the ear for 15-20 seconds to loosen debris
- Let your dog shake his head. Centrifugal force will bring all the goo to the top.
- Never use Q-tips to remove debris from the ear canal. It will only drive it further in, and could rupture the eardrum.
- Repeat on the other ear.
For specific products and instructions, consult your veterinarian
A dog’s sense of hearing is second only to its sense of smell in terms of superior ability and discernment. Dogs hear a wider range of frequencies than humans. Human hearing can detect sounds beginning at 20 hertz and ranging up to 12,000-20,000 hertz, depending on age. However dogs can hear in the range of 40-60,000 hertz, depending on breed and age. Dogs and humans both lose some ability to hear higher frequencies as they get older. Higher frequencies equate to a higher pitch noise. For example, a dog whistle produces sound between 16,000 and 22,000 hertz. This is out of range for most humans, but in the middle of the range of dog hearing.
The anatomy of the middle and inner ear is relatively the same in humans and dogs. Both have an eardrum, or tympanic membrane. Both species also have ossicles, or little bones in the inner ear that vibrate and send signals along the auditory nerve to the brain. The real key to better hearing in dogs is the 18 or more muscles that control a dog’s pinna, or ear flap. These numerous muscles allow a dog to finely tune the position of its ear canal to localize a sound, hear it more accurately, and from farther away. For this reason dogs with upright ears, such as terriers, tend to have superior hearing to dogs with floppy ears, such as hounds. It also means that dogs are much more sensitive to loud noises than are humans. Loud noises that are tolerated by humans may be scary or even painful to dogs.
Interestingly, dogs are born deaf, with closed ear canals. Most puppies’ ear canals will open by 10-14 days after birth. If a dog does not hear by 3 weeks of age, it should be tested for deafness by a veterinarian
21 Apr, 2016
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