Ear disease is one of the most common reasons your dog might visit the vets. Let’s discuss the most common kind of ear disease, how it develops, and how we diagnose and treat it, as well as some other less common ear issues your dog might have.
Table of contents
Otitis, or inflammation of the ear, is by far the most common disease of the ear seen in dogs (specifically otitis externa). We class otitis into otitis externa (from the ear flap to the eardrum), otitis media (from the eardrum to the hearing apparatus within the skull) and otitis externa (the hearing apparatus itself). Otitis media tends to develop as a consequence of a serious case of otitis externa, while otitis interna mostly develops if infection spreads from the mouth up the auditory tube.
In more everyday language, otitis externa is what we normally mean by an “ear infection”!
The most common symptoms seen with otitis externa are head shaking or scratching the ears, waxiness or pus leaking from the ears, smelly ears, painful ears, a head tilt or even partial deafness. Otitis media has the same, but can also present with pain on eating, regular yawning, drooping eyelids and face, or even balance issues and ‘drunkness’. Otitis interna is most likely to cause a head tilt, balance issues, abnormal eye movements, falling over and even vomiting.
Predisposing, Primary, Secondary and Perpetuating Factors
We break the causes of otitis up into predisposing, primary, secondary and perpetuating (PPSP) factors. It is important to understand these to know how we treat and prevent otitis.
Predisposing causes are factors that make it more likely for a dog to develop otitis
These include how the ear canal is shaped (some dogs are born with very narrow canals that make cleaning more difficult), how hairy the ears are, whether the ears are erect or floppy, how wet the ears are (both from the environment and due to swimming or bathing), any obstructions, trauma and skin allergies. Having any of these factors does not guarantee a dog will get otitis, but it increases their risk.
Primary causes of otitis are those that directly lead to ear inflammation
Allergies are the most common cause, including skin, food and medication allergies – if a dog is allergic and their skin becomes itchy, they are more likely to scratch, breaking the surface and causing inflammation. Certain parasites are also incredibly itchy for dogs, including Otodectes ear mites, Demodex mites and Sarcoptes mites. Puppies are especially vulnerable to these if not medicated with an appropriate parasite treatment. Foreign bodies stuck in the ear, such as grass seeds, will also lead to inflammation. There are also some hormonal and skin diseases that cause itchy skin and inflammation in the ear.
Secondary causes are those that develop as a consequence of the primary cause
Generally they are infectious agents. Cocci bacteria like Staphylococcus and Streptococcus are common, as are yeasts like Malassezia. In more severe cases, we can see rod bacteria such as Pseudomonas, or fungi like Aspergillus. These all create further inflammation and discomfort, making the otitis worse in a vicious cycle. Many cases of otitis are not identified by the owner until secondary disease is present.
Finally we have perpetuating factors – these are factors that cause the otitis to last longer, become more severe or recur
They include chronic thickening and narrowing of the ear canal wall, an increased number of wax secreting cells in the ear, damage to the eardrum and otitis media itself. Failing to identify these changes means otitis cannot be properly managed.
Diagnosing ear disease can be very simple or incredibly complex, depending on the specific case. We can often make an educated guess that there is otitis or secondary infection, but diagnosing and managing, predisposing, primary and perpetuating factors can be more difficult.
Diagnosis starts with taking a thorough history from the owner
How long have the ears been sore, one or both ears, how sore are they, has it happened before, does the dog swim, do you clean the ears, does your dog have any other skin issues, are they on any medication, and so on. This can help identify some of the PPSP factors.
We then examine your dog thoroughly, first nose to tail in case there is something relevant and to check their general health, and then the ears themselves
This requires the use of an otoscope to view inside the ear. Ideally, we want to be able to see all the way down to the eardrum, to ensure it is still intact, but this is not always possible. Pain, redness, thickening, discharge, waxiness, smell and wetness are all obvious signs of otitis externa. Sometimes, dogs’ ears are so uncomfortable, we cannot examine the ears safely, so we may start anti-inflammatory therapy first to reduce pain, then reassess a few days later. In extreme cases, we may have to sedate or anaesthetise animals for safe examination.
Ideally, we should always take a sample from the ear to determine what microorganisms are present, if any, and what we can kill them with
We can do this via swabbing inside the ear. Looking under a microscope can show us what category of organisms are present (cocci or rod bacteria, or yeast), but cannot tell us what drugs will kill them. This requires culturing at an external laboratory. We need to do this before we start any treatment so we know that the drugs we are using will be effective, reducing the risk of antimicrobial resistance or treatment failure. However, sampling the ear does not always happen due to cost, time, the dog’s welfare, and other factors.
More severe cases of otitis, particularly suspected media or interna, may require more advanced investigation. This may involve cutting into the eardrum to sample the middle ear (myringotomy), or x-rays, CT or MRI of the skull to view the middle and inner ear. Diagnosing these may also require a neurological examination to determine where the problem may be.
Treatment for otitis is as highly varied as the causes.
Otitis itself almost always needs some form of anti-inflammatory, such as steroids or NSAIDs
Sometimes, this is all a dog needs, even if there is a mild infection. These can be applied orally via tablets, or topically with drops, washes and ointments. Otitis is often very painful, so we sometimes provide additional pain relief if anti-inflammatories are not enough alone.
If there is infection (and remember, this should generally be proven first with an ear swab), then antibiotics or antifungals can be administered
If the eardrum is intact, then topical drugs work best as they get straight to the site of infection. Regular cleaning can also help break-down or remove bulky wax that can prevent drugs from killing the bugs. If the eardrum is ruptured, we cannot see the eardrum, or we suspect otitis media or interna, then oral drugs are safer. Some drugs last only a few hours, while others can last a week or more; so please discuss with your vet which may be right for your dog. If presumptive treatment without an ear swab does not work, then it should be mandatory to swab the ear at this point, so we do not create resistant microorganisms.
If these initial therapies do not work, we may have to consider more intense treatment
One option is a general anaesthetic to have the ears thoroughly cleaned by a vet using strong chemicals. This will remove large amounts of infection and wax but can leave the ears very sore. A GA is also riskier for very young or old patients. During the GA, some vets may pluck excessive hair too. This can be controversial.
On the one hand, very hairy ears are likely to trap wax, moisture and heat, leading to otitis, and hair prevents treatments getting deep into the ear. However, by removing the hair, it causes damage and further otitis to the skin, possibly making the problem worse. It is a fine balancing act, and generally only the hairiest ears should be plucked. We advise that plucking is only performed by a vet under sedation or a GA, and not by groomers, as this can cause otitis. It is also, of course, only a temporary solution until the hair grows back.
For dogs with very chronic, ongoing, and unmanageable ear disease, we may recommend radical surgery
The most common is a total ear canal ablation (TECA). This involves removing the ear canal itself, removing anywhere bacteria can colonise. Your dog will still have an ear flap, but there won’t be a hole into the ear itself. The surgery is not simple and carries several complications, including partial or full deafness on that side, wound breakdown (the procedure is often not very sterile), facial paralysis, bleeding, or recurrent abscesses. It should be considered a last resort for incurable otitis.
Alongside all of these treatments, it is important to treat the primary causes. This may include treatment for parasites, removing foreign bodies, treating allergies with anti-allergic drugs, treating other skin and hormonal diseases.
Preventing otitis involves managing all the aspects of PPSP. For your dog, this may mean preventing swimming, cleaning their ears regularly, preventing allergies flare-ups with diet, medication or avoidance, regularly treating with anti-inflammatories, and so on. Without minimising the effects of other factors, otitis recurrence will be much more common.
Other Ear Diseases
Though otitis is the most common ear disease in dogs, there are a few others which we will briefly go over.
The skin of the ear itself can become diseased. Often this is seen alongside otitis, but can be without otitis. Diseases may include mites, ticks, fleas, allergies, hormonal and autoimmune diseases, trauma, and cancer. There is also a condition called an aural haematoma, where the two layers of the ear separate and the pocket fills with blood. It is usually due to trauma after a dog scratches itself too much (often because of otitis), but trauma or clotting disorders can cause this too. We can fix aural haematomas by treating the underlying cause, draining the blood or stitching the two flaps together.
Within the ear canal, other diseases can occur. Some can be linked with otitis, but others are not. Polyps are a benign growth in the ear that look a little like cauliflowers. When small, they are hard to notice and cause little issue, but they can grow large, cause discomfort and block the ear canal. This can predispose an ear to otitis. We can remove them surgically or with thermocautery, but they can recur. Ears can also develop more serious masses, such as cancers. These can develop from any tissue in the ear, including skin, hair follicles, bones, wax cells and others. Treatment depends on the specific kind of cancer, but may involve surgical removal, chemotherapy or radiotherapy. Many are, thankfully, benign growths, unlikely to spread to other tissue.