ear infection symptoms causes and treatment for dogs and cats

Ear Infections in Dogs & Cats | Symptoms, Causes & Treatment

Ear infections are very common in pets, especially in dogs. The ears become very itchy and painful, and the pet will scratch at the ears and shake their head excessively. If they have long ears, it may sound like a helicopter is landing on your house (we affectionately call my dog Chopper Sam). Ear infections can be tricky. Most are easily treated, but there are times when the infection is resistant, and it can take a while to figure out exactly what will treat it. If ear infections are not treated, they can become chronic, the ears can swell shut, and can sometimes require drastic surgery. We will talk about the causes of ear infections, and how to help prevent them. While we will be mostly talking about dog ear infections (as they are much more common in dogs than our feline friends), all of this information applies to cats as well.

The Anatomy of a Dog Ear

It does not matter if your dog has floppy ears or ears that stand, the internal structures are the same (floppy ears just make more noise when they shake!). Their canal is different than ours. A human ear canal goes straight in without turning. This means that anything in the ear can come out easily. Dog and cat ear canals are not straight. They start by going down (vertical canal), then have an almost 90° turn to run to the canal (horizontal canal). This means that anything that goes in the ear (like excess moisture) has to go uphill to come out. This two part canal makes the dog much more susceptible to ear infections.


The following are symptoms of an ear infection:

  • Shaking the head and scratching the ears – this is the number one sign clients bring in their pets for when an ear infection is present. The dog will often keep everyone up all night shaking (again, can sound like a helicopter!) and scratching. The ears will often be very red, and sometimes painful when you touch them.
  • Discharge from the ear – another thing people will notice is “gunk” coming from the ear. This is often black/brown or yellow. This often persists after cleaning. This is because most OTC cleaners will clean the ears, but not treat the infection, which is causing the gunk.
  • Odor from the ear – “His head stinks!” The infections can definitely cause a foul smell in the ear, especially if they have been simmering for a while.


There are three main causes to ear infections in pets:

  • Moisture
  • Parasites
  • Breed disposition
  • Food allergies


The number one cause of ear infections in animals is excessive moisture in the ears. The moisture gets trapped down in the ear canal and forms a swamp. The bacteria and yeast that live on the skin normally then bloom in the swampy canal, and an infection is born! The moisture can come from several sources:

  • Allergies – the cause of probably 90% of all ear infections is allergies. The allergies cause a dog (or cat’s) skin to secrete more oils. This includes the skin on the ear pinna (flap). The oil falls down in the ear, and voila- instant swamp.
  • Swimming/bathing – it is possible that water that gets into the ear during bathing or swimming can lead to an ear infection. This usually happens when allergies are already present, or when the bathing/swimming is frequent and excessive. While possible, it is not near as likely as allergies. If you are worried about this, a routine ear cleaner used after bathing or swimming should flush the ears. You may also use a solution of 50/50 Rubbing alcohol/vinegar to flush the ear, but if the ear is red and irritated, this solution will burn.
  • I have seen one case of ear infection caused by one dog licking excessively at another dog’s ear, but this is not common.


Ear mites. This seems to be the first thing clients think of when an ear infection occurs. Ear mites are a tiny mite that invades the ear, and are infective. They are also rare in animals that live in a controlled environment. Ear mites are usually seen in stray cats and kittens (they are common in stray cats). In dogs they are usually seen in puppies from shelters and puppy mills. For pets that live in a house, apartment, etc, mites are extremely rare.

Breed Disposition

Some breeds are more predisposed to ear infections than others. Dogs with allergies (Westies, Golden Retrievers) often show their allergies with ear infections. Labs and German Shephards are prone to ear infections as well. Cocker Spaniels have the world’s worst ears by breed. Often this is not from infection but from excessive buildup of cerumen (oil and dead skin). Cockers tend to build new skin cells every 7-14 days (as opposed to the 21 days of other breeds). This leads to overproduction of cornified skin cells in the canal. These extra skin cells pile up, and the dog cannot get rid of them. This leads to a swelling of the canal, which can lead to infections. With Cockers, it is often beneficial start them on a cleaner that flushes the excess cerumen (Cerulytic) once weekly when they are puppies.

Food Allergies

If your pet has recurrent ear infections, especially if they happen year round (allergies to pollens tend to go away in the winter), then your pet may have an allergy to an ingredient in the food that it eats. It doesn’t mean the food is a bad food, just that your dog is reacting to it (much like lactose-intolerant people cannot drink milk). It also doesn’t matter if it is the same food he has always eaten. If so, a food change can help keep the ear infections from coming back.


Treatment usually involves a topical ointment placed in the ear. There are times when oral antibiotics or anti-inflammatory drugs need to be used as well. In rare cases, the bacteria in the ear is resistant and must be sent to the lab so that it may be tested to find out what antibiotics it is susceptible to.

Ear infections should be treated early. Chronic ear infections cause the ear canal to swell. If this happens over a long period, the canal can become ossified (form bone) and be permanently closed. If this happens, the only recourse could be surgery to remove the ear canal (ablation). This means the dog will be deaf, but often they are already deaf due to the infection.

Ear infections are very common and can be painful both to pet and owner. With proper (and timely) treatment, we can help get your pet taken care of and back to their happy and healthy lives.