Aural haematoma in dogs: a swollen ear flap

Overview

The ear flap and canal form a dog's outer ear. Flexible cartilage determines the flap's shape. On both sides, skin attaches closely to the membrane surrounding the cartilage. Branches of blood vessels pass through small openings in it. In an aural haematoma, fluid usually accumulates on the flap's concave inner surface. The haematoma may affect a small area or fill the whole flap. As blood accumulates, the flap may become a few centimetres thick at its widest point.

A fresh collection feels soft, sometimes like a water balloon. Blood trapped beneath the skin may clot. As swelling subsides, scar tissue can permanently alter the ear's position and shape.

Causes

Itching and ear injuries

Outer ear inflammation often causes itching that makes a dog scratch the ear. Scratching and vigorous head shaking can rupture a small blood vessel in the flap. Sometimes a direct blow or bite injures the flap.

Atopic dermatitis can cause inflammation particularly in ear canal skin. Food allergy can also cause itchy, inflamed ears. With ear mite infestation, intense itching and shaking can lead to an aural haematoma. A grass awn entering the canal can cause sudden irritation.

Ear cartilage and bleeding

The precise mechanism is not known in every case. An early study of 40 affected dogs proposed an immune reaction as the cause. Later tissue samples and blood tests from 15 dogs did not support an autoimmune explanation. Ear cartilage tissue samples have shown defects filled with new tissue rich in blood vessels. One possible mechanism is repeated strain where the ear flap folds. A clotting disorder can allow a haematoma to form without a known injury.

Risk factors

A British study investigated aural haematoma frequency using records from 887 veterinary practices in 2016. A new haematoma was recorded in 0.25% of study dogs during that year. Concurrent outer ear inflammation was recorded in 54.6% of haematoma cases. Allergic skin disease was recorded in 11.3%.

In these British dogs, the likelihood of an aural haematoma increased with age. Affected dogs had a median age of 8.17 years. Dogs without a recorded haematoma had a median age of 4.43 years. Haematomas were also more likely in dogs with greater adult bodyweight. Affected dogs had a median adult weight of 24.90 kg. In the other study dogs, the corresponding median was 13.90 kg. Compared with crossbreeds, the highest odds ratios were in Bull Terriers (7.42), St Bernards (7.28) and French Bulldogs (6.95). V-shaped drop ears had an odds ratio of 1.95 compared with erect-eared breeds. Semi-erect ears had a corresponding odds ratio of 1.60. Pendulous ears had an odds ratio of 0.59 compared with erect-eared breeds.

Typical symptoms

New swelling is usually most obvious on the inside of the ear flap.

• There is a soft, fluid-filled bulge in the flap.
• The swollen area may feel warm.
• Your dog may find the flap tender when touched.
• An ear that normally stands upright may droop under the blood's weight.
• Your dog may scratch the ear or shake their head repeatedly.
• The canal may smell unpleasant if it is also inflamed.

An older haematoma can become firmer as scar tissue forms. The flap may become red even in the early stages of swelling. An itchy dog may rub the ear against the floor or furniture. If canal inflammation is present, the ear may produce yellowish, brown or dark discharge. A sensitive dog may yelp or pull away when you try to examine the swollen ear.

Complications and consequences

A large haematoma may cover part of the canal opening. As blood is absorbed, the flap can become permanently folded or wrinkled: a so-called cauliflower ear. Severe scarring may narrow the canal even after swelling resolves. A surgical wound can become infected. Death of ear flap tissue is another possible complication. The ear can refill, particularly if the cause of irritation remains untreated. Permanent flap deformity may in turn predispose a dog to further outer ear inflammation. Scarring and wrinkling can also remain after treatment.

Diagnosis at the vet

Examining the ear flap and canal

Your vet asks when swelling began and about previous ear infections. A fluid-filled ear flap swelling suggests a haematoma. However, an abscess, cyst or tumour can also cause swelling. A fine-needle sample may be taken for cell examination if needed.

The canal is examined because disease there may underlie the swelling. An otoscope is used to examine the canal and check the eardrum if visible. A painful ear can be examined and cleaned under sedation. Video-otoscopy can improve the view, allow sampling and help remove a deeply lodged foreign body.

Investigating the cause of inflammation

Microscopy of canal discharge can identify bacteria, yeasts or ear mites. Recurrent otitis may require bacterial culture and antibiotic susceptibility testing. Itching and redness elsewhere on the skin may prompt allergy investigations. Investigating food allergy may require an elimination diet of at least 8 weeks, with only carefully selected food. Reintroducing the previous food afterwards helps establish whether symptoms return too.

With recurrent inflammation, canal skin may thicken and the canal narrow.

Ultrasound can reveal connective tissue partitions within a haematoma if needed. These may divide it into separate cavities between which fluid cannot flow.

Treatment

Drainage and medical treatment

Your vet can remove fluid from a fresh haematoma with a needle at the practice. Needle drainage alone works poorly for a longstanding haematoma. In a retrospective study of 49 dogs, all 23 needle-drained haematomas refilled immediately.

In some cases, your vet may combine drainage with local corticosteroid treatment. Oral anti-inflammatory medication may also be used in selected cases. In a small uncontrolled study, 21 of 24 dogs were judged to have at least an 80% improvement in signs after oral corticosteroid treatment. If the anaesthetic risk is high, your vet may consider allowing the haematoma to resolve without intervention.

Surgery and recovery

Surgery is performed under general anaesthesia or deep sedation. The haematoma is opened to remove fluid and clots. Sutures press the skin back against the cartilage, leaving less space for fluid. Instead of one long incision, several small drainage holes measuring 4 or 6 mm can be made in the flap. Sutures are placed along the ear's length to preserve blood vessels as far as possible. Sometimes a drain is attached to let further fluid escape from the cavity. A supporting bandage protects the flap and helps prevent additional shaking-related damage.

Your vet may remove a drain or dressing 3–14 days after the procedure. In some techniques, sutures remain for at least 3 weeks to allow skin to attach to cartilage. After surgery using a long incision and mattress sutures, removal may be possible after 10–14 days. Small drainage holes can be left open to close gradually as healing progresses. If the canal was inflamed, its recovery is checked separately. A new sample may be collected at an otitis recheck 1–2 weeks after treatment starts.

Recurrence and outcomes

A retrospective study of 51 dogs defined recurrence as a new haematoma at the same site after the first treatment month. After local corticosteroid treatment, 17 of 48 haematomas recurred. After multiple drainage-hole surgery, 1 of 24 recurred. Overall, 31% of dogs had multiple haematomas or a new one at another site. One haematoma initially treated with local corticosteroids ultimately underwent drainage-hole surgery.

Platelet-rich plasma prepared from the dog's own blood has been trialled for recurrent haematomas. In a 17-dog study, haematomas returned in 5 dogs within 7 days of the first plasma treatment. Two of these dogs moved to surgery and left the study. Twelve dogs healed after the first plasma treatment, with a mean healing time of 16 days. No recurrence was reported in the 12 dogs participating in telephone follow-up at 6 months. Clinical recovery required resolution of the haematoma, otitis and associated signs. Plasma treatment was not compared with a group treated by another method.

Prevention

Early treatment of irritating ear disease reduces scratching and the risk of further flap injuries. Weekly ear checks can help detect redness, discharge or unpleasant odour promptly. Unnecessary cleaning of a healthy canal may irritate its skin. Dry the ear flaps after swimming or bathing. Plucking canal hairs can irritate a healthy ear and trigger inflammation.

For recurrent otitis, maintenance care is planned according to the underlying condition. Allergic skin disease often needs long-term treatment even after ear inflammation settles.

Important for dog owners

Leave ear flap drainage to your vet because needle drainage requires a carefully cleaned procedure site. Do not use drops left over from a previous ear infection until the new symptoms have been examined. Some cleaners or drops can damage hearing or balance if the eardrum is ruptured.

Avoid inserting a cotton bud into the canal because it may push discharge deeper. Contact your practice if the flap starts bulging again after drainage. Tell your vet about previous ear symptoms or a blow to the ear.

Frequently asked questions

Can an aural haematoma resolve by itself?

Blood in the flap may gradually be absorbed without drainage. However, scar tissue may leave the flap thick and wrinkled. Veterinary examination can also establish whether canal inflammation needs treatment.

Why examine the canal when the swelling is in the flap?

Swelling may develop when a dog scratches an itchy ear or shakes their head vigorously. A canal sample can be checked for yeasts, bacteria or ear mites, for example. Treating the cause of itching reduces the risk of repeated flap damage.

Why does the flap refill after drainage?

Needle drainage removes fluid, but a space may remain between skin and cartilage where it can collect again. Surgery can therefore use sutures to attach the skin back against the cartilage. Continued scratching can damage the flap again.

Can the other ear develop a haematoma?

Haematomas can affect one or both ear flaps. A new one may develop in the other ear later, even after the first has been treated. In one study, dogs with allergic dermatitis had a greater risk of new collections.

When are the ear flap stitches removed?

Removal depends on the technique and how well the flap has healed. With some techniques, stitches support the flap for at least 3 weeks so that skin attaches to cartilage. If the canal was inflamed, your vet also checks its recovery at follow-up.