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Old Derby Animal Hospital

6 Reasons Why Your Dog Has a Swollen Ear

Light skinned woman veterinarian with long brown hair examining a brown Labrador dog and smiling

On average, a dog can hear four times better than humans.

Dogs can detect significantly more sounds from further away, and they can hear a wider range of frequencies.

When a dog’s ear becomes swollen, it is important to address the root cause of the issue and seek treatment right away. In this article, you will learn the 6 main reasons why your dog has a swollen ear and how you can help them. 


Your dog may have an infection in its ears. Infections cause inflammation, which includes swelling. Ear infections are pretty common in dogs and are typically caused by bacteria or yeast. Infections can occur inside or outside of your dog’s ears. Yeast infections are most likely to occur within the ear canals and can happen more often if your dog likes to swim. This is because water can become trapped in their ears, and a moist environment is ideal for yeast.


To do an initial check for an ear infection, examine the outside of your dog’s ears for any signs of damage. A bite wound or other laceration could start out innocently enough but might turn into a serious infection over time. Look for redness or other discoloration of the skin, and check for any bleeding or other fluids around the dog’s external ear area. Smell around your dog’s ears to see if you can detect any new odors. While a dog’s ears may not smell the best in normal circumstances, an infection could make them smell significantly worse.

Next, check the insides of your dog’s ears for similar signs of trouble. If there is any noticeable injury, redness, discoloration, bleeding, discharge, or a bad odor, it is likely that your dog has an infection and that this is the cause of the swelling. If your dog does have an ear infection, it will need to be seen by your veterinarian who can prescribe an antifungal or antibacterial medical treatment.


Your dog may have a swollen ear if it has allergies. Allergies can affect the skin of your dog, which includes their ears. If your dog is having an allergic reaction, it could be the cause of the swelling. Allergic reactions are a type of inflammation that can trigger your dog to shake its head and scratch at its ears. This in turn can lead to swollen ears in your pup.


Your dog may also be experiencing a different type of allergic reaction – a response to a bug bite or sting. Check to see if you can find any bumps or lumps on your dog’s ears. Be very gentle to avoid causing any additional pain.

Like humans, a lot of dogs can sustain a bug bite or sting and be okay, but there is always the chance that your dog may have a severe reaction to a bite or sting. Monitor your dog’s breathing, heart rate, activity levels, and the level of swelling in the affection area. If your dog is exhibiting signs of labored breathing, irregular heartbeat, a change in general demeanor, or rapid swelling, you will need to take your dog to a vet or emergency vet immediately.


Your dog may have something lodged in its ear. A build-up of wax or a foreign body can be a cause of swelling in a dog’s ears. The blockage alone can cause swelling, but a blockage of the ears can also lead to infection first and then subsequent swelling.

A veterinarian can remove excessive wax and determine if something else may be lodged in your dog’s ear. You may be able to see right away if something is stuck, but this is not always the case. If something small found its way into your dog’s ear, it is likely lodged past your line of sight into the dog’s ears. Ear canals run past what we can see, so it is important to have your veterinarian address the possibility of a foreign body in your dog’s ear.


Ear mites could be the cause of the swelling. These tiny pests are invisible to the naked eye, and they survive by eating the wax inside your dog’s ears. Inflammation, discharge, and hair loss are signs that your dog may have an ear mite infestation. Ear mites are contagious and can spread to any other pets or people in your home. A veterinarian can clean your dog’s ears and prescribe medical eardrops to remove the mites.


An ear hematoma occurs when the blood vessels in your dog’s ear burst and drain into the ear flap. This kind of rupture can lead to significant swelling. While the four causes mentioned above can lead to swelling on their own, they can each potentially lead to an ear hematoma. An infection, an allergic reaction, a blockage, and an infestation are each likely to cause your dog to shake its head and scratch at its ears. When the shaking and scratching get more vigorous and frequent, the blood vessels are much more likely to burst and create a hematoma.


If your dog has an ear hematoma, you will find that the affected ear has a fluid-filled pouch on its ear flap. It will be somewhat firm if you put light pressure on it. This will cause your dog discomfort and pain and will need to be treated. A veterinarian will examine the hematoma and determine the root cause of the rupture. To treat the hematoma, they will need to drain it and stitch it up. If the hematoma is small and the swelling is mild, your vet may prescribe a cortisone injection. If the hematoma is large, surgery may be needed to save the integrity of the ear.


As you can see, there 6 main reasons why your dog may have a swollen ear. Some of the main causes include: ear infection, allergy, insect bites, build up, ear mites and ear hematoma. It is important to keep a close eye on it and contact your veterinarian right away so that your pet can get the proper treatment.

At Old Derby Animal Hospital, we are dedicated to understanding your pet’s needs and providing the resources to keep them healthy and happy. If you have any questions about your dog’s swollen ear or want to schedule an appointment, give us a call at (781) 749-2800. You can also book an appointment online by filling out the online booking form. We are here for you and your pet and are always happy to help!