If your dog is shaking their head and you find dark gunk in the ear canal, you are looking at one of two very different problems: ear mites, or an ear infection. Ear mites are a contagious parasite (Otodectes cynotis) that colonises the ear canal, while an ear infection — otitis externa — is an overgrowth of yeast or bacteria that already live on your dog's skin. They look alike from the outside, they need completely different medication, and the only dependable way to separate them is an ear swab read under a microscope at your veterinary clinic.
Below are the clues Canadian owners can assess at home, why the distinction changes treatment, and the red flags that warrant a same-day appointment. For the full checklist, see our pillar guide to dog ear infection symptoms.
Ear mites or ear infection? A quick comparison
Use this as orientation, not diagnosis — mites and infections overlap more often than owners expect.
| What you notice | Ear mites (Otodectes cynotis) | Ear infection (yeast or bacterial) |
|---|---|---|
| Who tends to get it | Puppies, rescue and shelter dogs, homes with cats, dogs from rural or northern communities | Adult dogs, allergy-prone breeds, floppy-eared dogs, swimmers and lake dogs |
| Itch pattern | Sudden, ferocious, near-constant scratching and head shaking | Builds gradually over days or weeks; often worse in humid weather |
| Debris colour and texture | Dry, dark brown-black, crumbly — the classic "coffee grounds" look | Greasy brown wax (yeast) or moist yellow-green pus (bacterial) |
| Odour | Usually mild unless a second infection has set in | Distinct — musty and yeasty, or sharply foul |
| Spreads between pets? | Yes, readily, by direct contact | No — it reflects that individual dog's skin and ear environment |
| One ear or both? | Almost always both | Either; allergy-driven cases usually involve both |
What ear mites actually are
Otodectes cynotis is a surface-dwelling mite that lives on wax and skin debris inside the ear canal. It does not burrow, and the whole life cycle — egg to adult — runs roughly three to four weeks without leaving the ear.[1] Because transmission needs direct contact, mites cluster in litters, foster homes and multi-pet households; a dog sharing a bed with an infested cat is the textbook case, and shelters in Toronto, Montreal and Vancouver see it year-round.
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The signature is the itch: abrupt, frantic, and disproportionate to how the ear looks. Dogs scratch hard enough to bruise the ear flap. In a retrospective review of 100 dogs with otitis externa, mites were the primary underlying cause in roughly 7% of cases — uncommon overall, but a leading suspect in young dogs.[2]
What a dog ear infection is
Otitis externa is an overgrowth of organisms that normally live quietly on canine skin: most often the yeast Malassezia pachydermatis, or bacteria such as Staphylococcus and Pseudomonas.[2,3] It is nearly always secondary — to allergies, moisture from a swim in a Muskoka or Okanagan lake, a narrow or hairy canal, or wax that never clears. Change the ear's microclimate and the resident microbes take their chance.
Discharge gives you a working hypothesis. Greasy brown wax with a musty odour leans yeast; moist yellow-green discharge with a sour, sharp smell leans bacterial. We unpack that difference in our guide to yeast versus bacterial ear infections in Canada, and cover colour changes in detail in brown discharge in a dog's ear. Unlike mites, none of it is contagious to your other pets.
Why guessing costs you weeks
Mites need a parasiticide that kills mites and their eggs; yeast and bacteria need antifungal or antibacterial therapy. Neither product does the other's job, and either mistake buys the problem another two or three weeks to inflame the canal.
This is why veterinarians reach for ear cytology before prescribing. A swab of debris goes onto a slide: mites and eggs are visible directly, often with a drop of mineral oil, while yeast and bacteria are identified by shape after staining.[1] It takes about five minutes and is the single most informative step in an itchy ear.
The overlap most articles skip: mites invite infection
Mites and infections are not mutually exclusive. As mites inflame the canal they create the warm, damaged environment Staphylococcus and Malassezia exploit, and secondary infections are commonly documented alongside active infestations.[1] That explains a scenario Canadian owners describe often: the mites are gone, and the ear is still smelly and sore — because a second problem underneath was never swabbed for.
How each one is treated
For mites, veterinarians use proven parasiticides — the isoxazolines (afoxolaner, fluralaner, sarolaner) and macrocyclic lactones such as selamectin and imidacloprid–moxidectin all have supporting evidence, and cleaning the ear before treatment is recommended.[1,5] Because mites travel by contact, every dog, cat and ferret in the household must be treated at the same time, including the ones with no symptoms. Skipping the quiet cat is the most common reason an infestation returns a month later.[1]
For an infection, the sequence is a thorough clean followed by medicated drops chosen to match what cytology found — antifungal, antibacterial, or both, sometimes with an anti-inflammatory to settle the canal.[4] Our Canadian treatment guide walks through the options, and antifungal ear drops for dogs covers the topical options. Regular, gentle at-home ear cleaning supports either treatment and lowers the odds of a repeat.
Because so many canine ear infections are yeast-driven, many owners add inside-out support once the vet has addressed the primary cause. Pure Majesty Pets' Yeast Infection Drops offer gentle daily support for dogs prone to recurring yeast, alongside our yeast-relief collection. That is supportive care — no supplement clears a mite infestation.
When to see your veterinarian
Book an appointment if your dog will not let you touch the ear, if there is bleeding or a swollen, spongy ear flap (an aural hematoma), if the odour is strongly foul, if the head tilts or balance is off — signs the middle or inner ear may be involved — if nothing improves within a few days, or if infections keep returning. Ear disease can perforate the eardrum, and several common ear medications are unsafe once it is ruptured. For a structured home check first, our guide on how to tell if your dog has an ear infection walks you through it. Pure Majesty Pets supports ear and skin health from the inside out, but a veterinary exam is always the safe first move for a painful ear.
Mistakes that make it worse
- Assuming mites. In adult dogs, an itchy ear is far more likely to be yeast or bacteria.
- Treating only the itchy pet. Mites are contagious; leaving one animal untreated restarts the cycle.
- Pouring in hydrogen peroxide, rubbing alcohol or undiluted vinegar. These sting inflamed tissue and deepen the damage.
- Using leftover medication. A neighbour's drops may be the wrong drug — or dangerous if the eardrum is compromised.
- Stopping when the itch stops. Mite eggs and stubborn yeast outlast the visible symptoms.
Frequently asked questions
Can I see ear mites in my dog's ear?
Rarely. Adult mites measure under half a millimetre, so what you actually see is the dark, dry, coffee-ground debris they leave behind. A vet may spot movement through an otoscope, but confirmation comes from a swab under the microscope.
Do dog ear mites smell?
A straightforward mite infestation often has little odour. A strong musty or foul smell usually means yeast or bacteria have moved in on top of the mites, which changes what the ear needs.
Can ear mites cause an ear infection?
Yes. Mites inflame the canal and create the warm, irritated conditions yeast and bacteria thrive in, so secondary Staphylococcus and Malassezia infections are commonly found alongside them. A dog can genuinely have both at once.
Are dog ear mites contagious to my cat — or to me?
Very contagious between dogs, cats and ferrets by direct contact, which is why every pet in the home is treated together. Human infestations are documented but rare; wash your hands after handling an affected animal.
How much does an ear swab cost in Canada?
Fees vary by clinic and province, and cytology is usually billed on top of the exam. Ask when you book — most Canadian clinics quote both over the phone, and it costs less than a wasted course of the wrong medication.
Scientific References
- Companion Animal Parasite Council (CAPC). Otodectic Mite (Otodectes cynotis) guideline, dog. Updated 2019. capcvet.org.
- Saridomichelakis MN, Farmaki R, Leontides LS, Koutinas AF. Aetiology of canine otitis externa: a retrospective study of 100 cases. Vet Dermatol. 2007;18(5):341-347. doi:10.1111/j.1365-3164.2007.00619.x (PMID: 17845623)
- Bond R, Morris DO, Guillot J, et al. Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats: WAVD clinical consensus guidelines. Vet Dermatol. 2020;31(1):27-e4. doi:10.1111/vde.12809
- Nuttall T. Successful management of otitis externa. In Practice. 2016;38(S2):17-21. doi:10.1136/inp.i1951
- Yang C, Huang HP. Evidence-based veterinary dermatology: a review of published studies of treatments for Otodectes cynotis (ear mite) infestation. Vet Dermatol. 2016;27(4):221-e56. doi:10.1111/vde.12340
This article is for general educational purposes and does not replace veterinary advice. Ear disease can involve the eardrum and deeper structures; if your dog's ears are painful, smelly, bleeding or not improving, or if you notice a head tilt or loss of balance, please see your veterinarian for an exam and cytology before starting any treatment.