A dog’s ear drooping on one side usually signals one of a handful of problems: an ear infection, a blood blister inside the ear flap, a nerve issue, or, in puppies of erect-eared breeds, simply normal development. The drooping itself isn’t a disease but a symptom, and figuring out which cause is behind it depends on what other signs you’re seeing alongside it.
Ear Infections: The Most Common Cause
Outer ear infections are the single most frequent reason a dog’s ear starts hanging lower than usual. Swelling, fluid buildup, and pain make the ear feel heavy and uncomfortable, so your dog holds it down or off to the side. You’ll often notice other clues: a waxy yellow, reddish-brown, or dark discharge, a bad or fruity smell, redness inside the ear canal, and your dog scratching or shaking their head repeatedly.
When an outer ear infection goes untreated, it can spread deeper into the middle ear. Middle ear infections are more serious because several important nerves run right alongside that space. Damage to those nerves can cause a noticeable head tilt, loss of balance, rapid back-and-forth eye movements, and even facial paralysis on the affected side, where the lip and jaw look slack. Cavalier King Charles Spaniels are particularly prone to a condition called primary secretory otitis media, where thick mucus builds up behind the eardrum even without an obvious outer ear infection, causing pain, a head tilt, and balance problems.
Aural Hematoma: A Sudden, Puffy Droop
If your dog’s ear became swollen and floppy very suddenly, you’re likely looking at an aural hematoma. This happens when a blood vessel inside the ear flap bursts, filling the space between the skin and cartilage with blood. The ear flap looks puffy, feels soft and warm to the touch, and droops under its own weight. It can appear almost overnight.
Hematomas sometimes follow a direct knock or injury, but more often they develop after prolonged, vigorous head shaking or scratching from an underlying ear infection or allergy. The shaking itself ruptures the blood vessel. Without treatment, the blood eventually reabsorbs on its own, but the ear flap typically heals crumpled and thickened, sometimes called “cauliflower ear.”
Surgical drainage is the most reliable fix. A vet makes a small incision, removes the clot, and places sutures through the ear flap to hold the layers of skin back together while healing. Drainage tubes or bandages come out within 3 to 14 days, and most dogs recover fully within about two weeks. In more severe cases, sutures may stay in place a bit longer. The chance of the hematoma returning after surgery is very low.
Ear Mites and Chronic Irritation
Ear mites are tiny parasites that live inside the ear canal, feeding on wax and oils. They trigger intense itching and inflammation. In dogs with normally upright ears, the irritation and swelling can cause the ear to droop. You’ll typically see a crusty, blackish-brown discharge that looks like dried shoe polish, and your dog will scratch at the affected ear relentlessly. In severe cases, the ear canal becomes so inflamed it produces pus, and the eardrum can rupture. Left unchecked, the constant scratching and head shaking from mites can also lead to a hematoma, compounding the problem.
Nerve Damage and Facial Paralysis
Sometimes a drooping ear has nothing to do with what’s happening inside the ear itself. The facial nerve controls muscle tone across one side of the face, including the muscles that hold the ear in its normal position. When that nerve is damaged, the ear loses its ability to stand or move normally and simply hangs.
Facial nerve paralysis can result from a middle ear infection pressing on the nerve, trauma, or a tumor near the nerve’s path. In some dogs, no cause is ever identified. This is called idiopathic facial paralysis. Dogs with this condition show a drooping ear, a sagging lip on the same side, drooling, and food collecting in the cheek on the paralyzed side. The drooping looks different from infection-related drooping because the ear flap itself isn’t swollen, red, or warm. It simply lacks muscle tone.
Vestibular Disease and Head Tilts
A condition that sometimes gets mistaken for a droopy ear is vestibular disease, which affects the balance system. Dogs with vestibular disease tilt their entire head sharply to one side, which can make it look like one ear is drooping when really the whole head is off-kilter. Other signs are hard to miss: stumbling or walking in circles, falling to one side, rapid eye flicking, and sometimes nausea or refusal to eat.
Idiopathic vestibular syndrome, the most common form, comes on suddenly and looks alarming but typically improves quickly over a few days to weeks. It’s most common in older dogs and is sometimes called “old dog vestibular disease.” The peripheral balance system malfunctions without a clear reason, then gradually resets itself. A persistent head tilt may linger even after other symptoms resolve.
Normal Development in Puppies
If you have a young puppy of a breed that’s supposed to have erect ears, like a German Shepherd, Siberian Husky, or Belgian Malinois, one ear flopping while the other stands up is almost always normal. Ear cartilage strengthens gradually, and during teething (roughly 3 to 6 months of age), ears frequently go up, flop back down, or take turns. One ear may stand weeks before the other catches up. This back-and-forth is especially common around 4 to 5 months and resolves on its own in most puppies as the cartilage firms up after teething finishes.
What to Look For at Home
Before calling your vet, a quick inspection can help you describe what’s going on. Gently lift the ear flap and look inside the canal. You’re checking for a few specific things:
- Discharge color. Yellow, reddish-brown, or dark waxy buildup suggests infection. Black, crumbly debris points toward mites.
- Smell. A sour, yeasty, or fruity odor is a strong sign of infection.
- Swelling of the flap. A puffy, balloon-like ear flap that feels warm and soft is likely a hematoma.
- Pain response. If your dog flinches or yelps when you touch the base of the ear or when they open their mouth to chew, the problem may involve the middle ear.
- Balance and coordination. Stumbling, circling, or a head tilt alongside the droopy ear points to either vestibular disease or a deeper ear infection affecting the nerves.
How Vets Diagnose the Cause
A vet will typically start with an otoscopic exam, using a lighted scope (or a tiny video camera) to look down the ear canal and check for redness, foreign objects, polyps, or a damaged eardrum. If discharge is present, they’ll take a small sample for ear cytology, examining it under a microscope to identify whether bacteria, yeast, mites, or just inflammatory cells are present. Cytology that shows inflammation without any organisms usually points to allergies or irritation rather than infection.
For suspected middle ear involvement or nerve damage, imaging like X-rays, CT scans, or MRI may be needed to see structures behind the eardrum. If vestibular disease is suspected, the vet will evaluate eye movements, balance, and coordination to determine whether the problem is peripheral (inner ear) or central (brain).
Why Timing Matters
Ear problems that seem minor can escalate. Untreated outer ear infections can push deeper into the middle ear, where nerve damage becomes a real risk. Hematomas left alone heal with permanent scarring and deformity of the ear flap. Chronic mite infestations can cause hearing loss. If you notice discharge, swelling, odor, pain, or any balance problems alongside that drooping ear, those are signs the problem needs professional attention sooner rather than later.