Dogs get ear mites almost exclusively from direct contact with another infected animal. The mite responsible, Otodectes cynotis, spreads between dogs, cats, foxes, and ferrets, and the single most common source for an adult dog is a cat carrying the mites. Understanding how these tiny parasites move from host to host helps explain why some dogs seem to pick them up repeatedly while others never do.
Direct Contact Is the Primary Source
Ear mites cannot fly or jump. They crawl from one animal to another during close physical contact: nose-to-nose greetings, play, sleeping in the same bed, or a mother nursing her puppies. This direct transfer is by far the most common route. Dogs that spend time around other animals, whether at a dog park, boarding facility, grooming salon, or shelter, face a higher risk simply because they have more opportunities for contact with an infected host.
Cats deserve special mention. As many as 10% of cats carry ear mites without showing any symptoms at all. These silent carriers act as a persistent reservoir, passing mites to dogs that share a household or yard without their owners ever realizing the cat is infested. If your dog has ear mites and you also have a cat, the cat is a likely source even if its ears look perfectly normal.
Contaminated Objects and Surfaces
While direct animal-to-animal spread accounts for most cases, ear mites can also travel on shared bedding, blankets, grooming tools, and other items that touch an infected animal’s head or ears. These indirect sources (sometimes called fomites) matter most in multi-pet homes, shelters, and kennels where animals share equipment and sleeping areas.
The window for this kind of transmission is limited by how long the mites survive without a host. In cooler temperatures around 10°C (50°F), mites can live off a host for 15 to 17 days. In warmer conditions closer to 34°C (93°F), they survive only 5 to 6 days. Under typical indoor conditions, the practical maximum is roughly 12 days. That’s long enough for a mite to hitch a ride on a blanket that hasn’t been washed in a while, but short enough that thorough cleaning breaks the cycle.
Can Dogs Pick Them Up Outdoors?
Dogs that spend a lot of time outside, particularly in wooded areas or tall grass, are more likely to encounter ear mites. The mites can survive briefly in the environment, and wildlife like foxes and stray cats can deposit them in areas your dog explores. That said, mites need a living host to feed on and reproduce, so they don’t build up in soil or grass the way ticks do. The outdoor risk is real but lower than the risk from direct contact with another pet.
Which Dogs Are Most Vulnerable
Puppies and young dogs are infected far more often than healthy adults. Part of this is behavioral: puppies have constant close contact with their mothers and littermates, and mites pass easily among them. Part of it is immunological: a mature immune system offers some resistance that puppies haven’t developed yet.
Dogs that are immunosuppressed or under stress are also more susceptible. An otherwise healthy adult dog can even carry mites without showing symptoms, only developing a full-blown infestation after a stressful event like a move, surgery, or illness. This is one reason ear mites can seem to appear “out of nowhere” in a dog that hasn’t recently been around other animals.
How the Infestation Develops
Once a mite reaches your dog’s ear canal, things move quickly. The entire life cycle, from egg to adult, takes about three weeks. Mites feed on skin oils and ear wax, and their waste products trigger an inflammatory reaction. The classic sign is a dark, dry, crumbly discharge that looks like coffee grounds. This material is a mix of ear wax, dried blood, inflammatory debris, and the mites themselves.
You’ll typically notice your dog scratching at one or both ears, shaking their head, or tilting it to one side. The ears may smell bad and appear red or swollen inside. Some dogs scratch hard enough to cause wounds around the ear that can become infected on their own.
Why All Pets in the Home Need Treatment
Ear mites spread rapidly in a household. If one pet is diagnosed, every dog and cat in the home should be treated, even those with no visible symptoms. Remember that cats especially can harbor mites silently. Skipping a seemingly healthy pet is the most common reason ear mite infestations keep coming back.
Cleaning matters too. Wash or replace all shared bedding, and clean grooming tools thoroughly. Because mites can survive up to two weeks on surfaces in cooler environments, a single deep clean at the start of treatment may not be enough if the home stays cool. Repeating the process a week or two later helps ensure no surviving mites reinfest a freshly treated pet.
How Ear Mites Are Confirmed
A veterinarian typically takes a small sample of the dark ear discharge, places it on a slide with a drop of mineral oil, and examines it under a microscope. The mites are visible as tiny, white, moving specks. In some cases they can even be seen with an otoscope during a routine ear exam. The diagnosis is straightforward, and treatment with modern antiparasitic medications is highly effective when applied to every animal in the household.