What causes discharge from ears in dogs?

Bacterial Infection or Outer Ear Infection

Some dogs, such as Cocker Spaniels, Sheepdogs, and other breeds with large, floppy ears are more prone to infections of their outer ear (otitis externa) or the ear flap area due to their anatomy. However, ear infections can occur in any breed.

A bacterial infection of the outer ear often appears as waxy and brown, red and inflamed, or yellow and purulent. Outer ear infections often have a noticeable smell, and may be very itchy and uncomfortable for your dog. They may be caused by excessive wax build up, a scratch or injury that became infected, excessive swimming or bathing, ear mites, and more.

Internal Ear Infection

If an outer ear infection is left untreated, it can progress down the ear canal and cause an inner ear infection (otitis interna) or a middle ear infection (otitis media). Symptoms of an internal or middle ear infection are similar to those of an outer ear infection, but may progress to signs such as head tilting, loss of balance, drooling, and circling.

Yeast Infection

Yeast infections are very common in dogs. The presence of yeast in your dog’s ear is actually normal, but when the ear environment becomes inflamed, yeast can overgrow, causing a brown, waxy, or greasy build up. There is usually a noticeable smell, and your dog will likely be quite itchy.

Ear Mites

Ear mites are a microscopic parasite that can inhabit your dog’s ear canal. Although ear mites are more commonly seen in puppies, they are highly contagious between dogs, so we can’t rule out the possibility of ear mites in adult dogs.

Ear mites create a dark colored, waxy discharge that can sometimes resemble coffee grounds. Ear mites will be itchy, so scratching and head shaking are two common indications.

A possible ear mite infestation. They typically create a dark waxy discharge, however, diagnosis requires viewing under a microscope.


It is possible for dogs to rupture their eardrum(s). The eardrum, also known as the tympanic membrane, is a thin membrane that separates the outer ear from the middle and inner ear.

A ruptured eardrum can occur as a result of injury or trauma, untreated infection, sudden (and severe) change in atmospheric pressure, and very loud noises. Signs your dog has ruptured their ear drum include:

  • Bloody and/or purulent discharge from the ear
  • Hearing loss
  • Head tilt
  • Loss of balance
  • Pain and inflammation of the ear


A hematoma is also a possible trauma that can occur from excessive scratching at an untreated ear infection. A hematoma occurs when the ear flap fills with blood and becomes swollen.


Dogs that suffer from any type of skin allergies or environmental allergies are more prone to ear infections. Dogs with allergies usually have an overworked immune system, so fighting off bacterial and yeast overgrowth is more difficult for these pets, making secondary ear infections more common. In these cases the underlying issue (i.e the allergy) needs to be addressed to prevent future ear infections.

Excessive Wax Buildup

Ear wax is a completely normal substance in your dog’s ear. Just like in humans, ear wax is formed to collect debris, dead cells, dirt, pollen etc. A little bit of ear wax is normal (and actually healthy) for your dog’s ears. If you think your dog may have an overgrowth of ear wax, consult with your veterinarian.

As a general rule of thumb, if your dog shows signs of irritation (ex. constant scratching), there is likely excessive ear wax.

Excessive Cleaning

Excessive cleaning of your dog’s ears can disrupt the natural pH of the ear, and actually cause ear infections. If your dog’s ear appears normal, there is no need to clean it.

If you are unsure whether or not your dog’s ear looks normal, consult with your veterinarian. A general rule of thumb for a healthy dog is to only clean your dog’s ears if there’s visible wax buildup, and no more than once a week.

Pro Tip: f your dog’s ear looks normal, there’s no need to clean it. Excessive cleaning of the ears can actually do more harm than good for your dog’s ears.

Excessive cleaning can disrupt the natural pH balance of your dog’s ears, causing more harm than good.