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Aural Hematoma in Dogs - A Complete Clinical Overview

Definition

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Anatomy of the Canine Pinna (Relevant to Pathology)

• A central layer of auricular cartilage (scapha)
• Hairless skin on the concave (medial/inner) surface
• Haired skin on the convex (lateral/outer) surface
• Auricular arteries and veins running longitudinally along the medial (cranial/rostral) and lateral (caudal) margins of the pinna
• Small perforating vascular branches that traverse through the cartilage to supply both skin surfaces

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Pathophysiology

1. Mechanical shearing forces are created when a dog shakes its head violently or strikes the pinna against a hard surface.
2. These shearing forces generate a "stress-riser" effect at the junction between the small perforating vessels and the semi-rigid pinnal cartilage.
3. This causes rupture of one or more perforating vessels, with blood escaping into the connective tissue gap between the medial and lateral cartilage layers - causing the central scaphal cartilage to partially separate or "delaminate."
4. Blood accumulates under pressure, expanding the hematoma. The thinner lateral cartilage layer can stretch asymmetrically, while the thicker medial layer resists deformation.
5. If left untreated, fibrin forms, leading to progressive fibrosis, contraction, and thickening of the auricle - resulting in the classic "cauliflower ear" deformity.

Note: Earlier literature suggested the blood collected between the medial pinnal skin and perichondrium, but current evidence points to intra-cartilaginous delamination as the primary mechanism.

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Etiology and Predisposing Causes

Infectious / Parasitic (most common)

• Otitis externa - bacterial (Staphylococcus, Pseudomonas, Proteus) or yeast (Malassezia)
• Ear mites (Otodectes cynotis)
• Flea infestation

Allergic / Hypersensitivity

• Atopic dermatitis (environmental allergies) - the single most common predisposing cause
• Food hypersensitivity / adverse food reactions
• Contact hypersensitivity

Endocrine

• Hypothyroidism
• Hyperadrenocorticism (Cushing's disease)

Structural / Neoplastic

• Polyps, masses, or foreign bodies in the ear canal

Traumatic

• Direct blunt trauma to the pinna
• Vigorous scratching

Autoimmune / Degenerative

• Degenerative changes in auricular cartilage
• Immune-mediated vasculitis

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Signalment and Breed Predisposition

• Dogs are more susceptible than cats.
• Floppy-eared (pendulous ear) breeds are at higher risk: Cocker Spaniels, Basset Hounds, Labrador Retrievers, Golden Retrievers, Beagles.
• Breeds with erect ears can also be affected.
• Typically unilateral; bilateral involvement is rare and should prompt investigation for a systemic or immune-mediated cause.
• Any age, sex, or breed can be affected.

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Clinical Signs

• Soft, fluctuant swelling of part or all of the pinna (the hallmark sign)
• The swelling may feel warm and is typically non-painful or mildly painful on palpation
• Fluid-filled appearance of the ear flap
• Head shaking and head tilting (often the inciting behavior)
• Ear scratching / pawing at the ear
• The pinna may droop or hang more heavily than normal
• Signs of concurrent otitis: malodor, discharge, erythema of the ear canal
• Chronic / untreated cases: pinna thickening, wrinkling, scarring (cauliflower deformity)

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Diagnosis

Physical Examination

• Identification of the classic fluctuant, blood-filled swelling of the pinna
• Palpation reveals a soft-to-firm fluid pocket
• Transillumination or needle aspiration confirms blood within the cavity

Ear Canal Examination (Otoscopy)

• Mandatory to identify the underlying cause
• Examine for: cerumen accumulation, discharge, erythema, foreign bodies, polyps, masses, ear mites
• Collect samples for cytology if discharge is present

Diagnostic Workup for Underlying Cause

• Ear cytology: identify bacteria, yeast, or mites
• Ear culture and sensitivity: if infection is suspected
• Skin allergy testing / food elimination trial: if atopic or food allergy is suspected
• Bloodwork (CBC, biochemistry, thyroid panel): if endocrine disease is suspected
• Ultrasound: can detect internal septa within the hematoma (relevant for surgical planning and for identifying recurrent/loculated hematomas with PRP treatment)

Differential diagnoses include: abscess (warm, painful, may have puncture wound), seroma, neoplasia, and bee sting/insect bite reaction.

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Treatment

1. Treat the hematoma (drain it + prevent reaccumulation)
2. Treat the underlying cause (otitis, allergy, parasites, etc.)
3. Prevent recurrence

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1. Surgical Management (Gold Standard)

• Performed under general anesthesia
• An S-shaped or linear incision is made on the concave (medial/inner) surface of the pinna over the hematoma
• Hematoma contents (blood, fibrin clots) are evacuated and the cavity is flushed
• Multiple through-and-through mattress sutures are placed to obliterate the dead space and directly reappose the skin to the perichondrium/cartilage
• Sutures remain in place for 3-4 weeks to allow fibrous adhesion
• The ear is bandaged to the head to prevent movement and re-injury

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2. Less-Invasive Drainage (Drain Placement)

Passive Drains (e.g., Penrose drain, teat cannula)

• A fenestrated tube (Penrose drain or teat cannula) is placed through the pinna to allow passive drainage
• Can be done under sedation rather than full general anesthesia
• Disadvantage: pinna layers are not directly apposed, increasing risk of fluid reaccumulation and delayed healing

Active/Vacuum Drain System (Laterally Placed)

• A novel approach developed at MSPCA-Angell: a vacuum drain is placed on the convex (lateral) surface of the pinna
• The activated reservoir creates negative pressure, drawing the pinna layers together
• No bandage required; protected by an Elizabethan collar
• Excellent cosmetic results when applied early; minimizes scar tissue deposition
• Advantage: minimally invasive, excellent cosmesis, no bandage needed

CO₂ Laser Incision

• Used in some centers for incisional drainage; reduces bleeding and inflammation

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3. Conservative Management

Aspiration + Intralesional/Intracavitary Corticosteroid

• Blood is aspirated via needle, and a corticosteroid (e.g., triamcinolone, dexamethasone) is injected directly into the cavity
• Reduces inflammation and may prevent recurrence by decreasing exudate formation
• Higher recurrence rate than surgical management
• Useful in dogs that are poor surgical candidates

Oral Corticosteroids (e.g., Prednisolone)

• Oral prednisolone alone has shown efficacy in some studies (PMID: 35652255 - Rüfenacht et al., 2022)
• Works by reducing inflammation, vascular permeability, and re-exudation
• Best suited for early/small hematomas or when surgery is declined
• Risk: systemic steroid side effects; higher recurrence without drainage

Platelet-Rich Plasma (PRP)

• Emerging treatment for recurrent aural hematomas
• PRP is injected after aspiration; promotes healing and tissue reapposition
• Ultrasound can guide treatment by identifying internal septa in complex or recurrent cases (PMID: 37570265 - Palagiano et al., 2023)

Polycaprolactone (PCL) Splint (Novel, 2025)

• A recent case series (JAVMA 2025, PMID: journal article) reported successful AH management in 7 dogs and 3 cats using application of a polycaprolactone splint to compress and reappose pinna layers post-drainage

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Comparison of Treatment Approaches

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Postoperative Care

• Elizabethan collar (E-collar): essential to prevent pawing and re-injury
• Ear bandaging: protects and immobilizes the pinna; prevents head shaking trauma
• Suture removal at 3-4 weeks post-surgery
• Treatment of underlying cause is mandatory to prevent recurrence (e.g., antibiotics/antifungals for otitis, allergen management)
• Recheck examination in 1-2 weeks post-procedure

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Complications

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Prognosis

• Good to excellent with appropriate treatment of both the hematoma and the underlying cause
• Early intervention yields better cosmetic results and lower recurrence
• If the underlying cause (e.g., allergy, chronic otitis) is not controlled, recurrence is highly likely
• Untreated hematomas that organize and fibrose result in a permanently deformed "cauliflower" ear - not life-threatening but cosmetically disfiguring

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Key Clinical Pearls

1. Always identify and treat the underlying cause - without this, recurrence is almost certain.
2. Surgical incision with mattress sutures remains the gold standard for definitive treatment.
3. Early treatment produces the best cosmetic outcomes and reduces the risk of fibrotic deformity.
4. Bilateral aural hematomas are uncommon and should raise suspicion for a systemic or immune-mediated disorder.
5. The hematoma forms by intra-cartilaginous delamination (not under the skin), which is why direct compression/apposition of cartilage layers is key to successful treatment.
6. E-collar compliance is non-negotiable post-treatment.

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• Hardie RJ, Aubrecht AM. Treatment Approaches for Canine Aural Hematoma. Clinician's Brief, May 2023.
• Minimally Invasive Vacuum Drain Technique. MSPCA-Angell.
• Rüfenacht S et al. (2022). Oral prednisolone monotherapy for aural hematoma in dogs. PMID: 35652255
• Palagiano P et al. (2023). PRP treatment with ultrasound detection for recurrent aural hematoma. PMID: 37570265
• Chen Y et al. (2025). PCL splint application for aural hematoma in dogs and cats. JAVMA 263(5).

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Affections of the Hoof - A Complete Veterinary Overview

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Anatomy Relevant to Hoof Pathology

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SECTION I: AFFECTIONS OF THE HORSE'S HOOF

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1. Laminitis (Founder)

1. Sepsis/endotoxemia - Bacteria or bacterial toxins enter the bloodstream (e.g., from grain overload, colitis, retained placenta, metritis), causing vasoactive changes in the laminar vasculature
2. Hormonal/endocrine - Equine Metabolic Syndrome (EMS), Equine Cushing's Disease (PPID); insulin dysregulation causes direct lamellar cell damage
3. Supporting limb laminitis - Increased mechanical load on a contralateral limb following severe lameness or fracture

• Grain/carbohydrate overload (most common)
• Grazing lush pasture (especially ponies)
• Black walnut heartwood shavings exposure
• Excessive road work / hard exercise
• Retained placenta after foaling
• Treatment with corticosteroids

• Developmental phase: After trigger, before clinical signs (12-18 hours in grain overload)
• Acute phase: Active inflammation, severe pain, no rotation yet
• Subacute: Inflammation subsides without structural change
• Chronic: Lamellar failure leads to coffin bone rotation or sinking (founder)

• Classic "sawhorse stance" - weight shifted to hindquarters, forefeet extended
• Bounding digital pulses (palpable at the fetlock)
• Warm hooves
• Unwillingness to move; walks on heels
• Pain on hoof tester application at the toe
• In chronic: "founder rings" (growth rings wider at heel), flat/dropped sole, white line widening

• Immediate removal of inciting cause
• Deep soft bedding or sand (conforming to sole)
• Digital hypothermia (icing feet) - protective in the developmental and early acute stages for septic laminitis
• NSAIDs (phenylbutazone, flunixin) for pain and anti-inflammation
• Therapeutic shoeing (heart bar shoes, deep digital flexor tendon tenotomy in severe rotation)
• Pergolide for PPID; dietary management for EMS

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2. Navicular Disease (Palmar Hoof Pain / Navicular Syndrome)

• Synovitis of the navicular bursa
• Degenerative changes in the navicular bone (cyst formation, ossification of collateral navicular ligaments)
• Erosion of the fibrocartilage on the flexor surface of the navicular bone

• Bilateral forelimb lameness, worse on the concave limb (circle)
• Heel pain on hoof tester application
• Pointing of the affected foot at rest
• Short, choppy stride; toe-first landing
• Gradual deterioration over months to years

• Corrective shoeing with egg-bar or wide-web shoes, rolled toes, raised heels
• NSAIDs
• Bisphosphonates (tiludronate, clodronate) - IV or regional perfusion
• Navicular bursa injections (corticosteroid)
• Neurectomy (palmar digital neurectomy) as a last resort

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3. Hoof Abscess (Subsolar / Sublamellar Abscess)

• White line defects or cracks
• Puncture wounds of the sole
• Hoof wall separations
• Bruising that creates a seroma that becomes infected

• Sudden onset severe (grade 4-5/5) lameness
• Bounding digital pulse
• Warm hoof
• Localized pain on hoof tester
• Swelling above the coronet if abscess tracks upward

• Establish drainage (pare sole, open abscess pocket)
• Poultice the foot to draw remaining infection
• Soaking in warm Epsom salts water
• Keep clean; bandage
• Antibiotics only if cellulitis or severe infection extends proximally

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4. Thrush

• Black, foul-smelling discharge from frog clefts
• Soft, crumbling frog tissue
• Pain on pressure to the frog (may be minimal until advanced)
• Severe cases extend into sensitive frog and digital cushion

• Clean environment (dry bedding)
• Daily hoof picking
• Debridement of necrotic frog tissue
• Topical antiseptics (iodine, copper sulfate, commercial thrush products)
• In severe cases: systemic antibiotics

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5. White Line Disease (Seedy Toe / Hollow Wall)

• Mechanical stress (long toe, underrun heels, poor trimming) creates microfissures at the white line
• Anaerobic bacteria and fungi invade the cavity
• Keratin-digesting organisms break down horn, creating a crumbling, hollow cavity
• Can progress to undermine the entire toe wall

• "Hollow" sound when hoof wall is tapped at the toe
• White line widening visible on solar surface
• Crumbly, gray/black powdery material in the cavity
• Lameness is infrequent unless coffin bone rotation occurs

• Resection of undermined hoof wall (remove the roof of the cavity)
• Debridement and cleaning
• Allow cavity to dry out; topical antiseptics
• Therapeutic shoeing to offload the area
• Treat underlying laminitis if present

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6. Hoof Wall Cracks (Sand Crack / Grass Crack)

• Sand crack (coronary crack): Originates at the coronary band, extends downward. More serious - may involve sensitive laminae
• Grass crack (ground crack): Originates at the bearing surface, extends upward. Usually superficial
• Quarter crack: Located at the quarter region; most common in racehorses
• Toe crack: At the toe

• Correct imbalance and shoeing
• Stabilize the crack with wire sutures, acrylic patch, or hoof staples
• Coronary band injection if scarring is present
• Ensure adequate hoof moisture and nutrition (biotin, methionine, zinc)

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7. Canker (Chronic Hypertrophic Pododermatitis)

• Soft, spongy, cottage cheese-like proliferative tissue on the frog and sole
• Foul odor (less putrid than thrush)
• Bleeds easily on paring
• Lameness variable; may be mild despite extensive lesions
• Does not respond to standard thrush treatment

• Thorough surgical debridement under anesthesia
• Keep hoof clean and dry
• Topical antiseptics (metronidazole-based preparations, copper sulfate)
• Systemic metronidazole ± penicillin
• Bandaging and stall rest
• High recurrence rate

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8. Quittor (Lateral Cartilage Necrosis)

• One or more draining sinuses at or above the coronet band
• Swelling at the coronet
• Lameness
• Chronic, recurring nature

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9. Pedal Osteitis

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10. Sidebone (Ossification of Lateral Cartilages)

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11. Pyramidal Disease (Extensor Process Fracture / Buttress Foot)

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12. Keratoma

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13. Bruised Sole / Corns

• Bruised sole: Hemorrhage and inflammation in the solar corium from excessive concussion, flat feet, or thin soles. Red/purple discoloration on pared sole.
• Corn: A specific bruise at the "seat of corn" (between the wall and bar at the heel). Common in horses with contracted heels or improper shoeing. Treatment: remove pressure, corrective shoeing.

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SECTION II: AFFECTIONS OF THE CATTLE HOOF

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A. INFECTIOUS HOOF LESIONS

1. Digital Dermatitis (Mortellaro's Disease / Hairy Heel Warts)

• M0: Normal skin
• M1: Small (<2 cm), red, active lesion
• M2: Classic large (>2 cm), red/gray, painful, proliferative active lesion
• M3: Healing stage (dark scab)
• M4: Chronic stage (raised, wart-like, proliferative)
• M4.1: M4 with active M2 center

• Acute severe lameness
• Painful ulcerative lesion at the back of the foot (heel bulbs)
• Strawberry-like or wart-like appearance
• Foul odor
• Hair loss around the lesion ("hairy heel warts")

• Individual: Topical tetracycline (oxytetracycline) spray or paste, with or without bandage (remove within 24 hours)
• Herd: Foot baths (tetracycline, copper sulfate, formalin, acidified ionized copper solutions)
• Clean and dry housing; hygiene protocols

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2. Foot Rot (Foul-in-the-Foot / Interdigital Phlegmon)

• Bacteria enter through skin defect in the interdigital space
• Trauma from stones, stubble, moisture, dried mud predisposes to skin damage
• Rapid spread through subcutaneous tissues; characteristic foul smell

• Sudden severe lameness (grade 3-4/4)
• Symmetrical swelling (hot, painful) just above both claws - key distinguishing feature
• Necrosis of interdigital skin; foul smell
• Usually one foot; rear feet more common
• Fever, reduced milk yield, inappetence

• Systemic antibiotics (penicillin, oxytetracycline, ampicillin, florfenicol, ceftiofur) - label directions
• Improvement within 2-3 days expected
• No need to remove necrotic tissue or bandage in uncomplicated cases
• If unresponsive - check for deep digital sepsis (joint/tendon involvement)

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3. Heel Horn Erosion and Interdigital Dermatitis

• Wet, dirty conditions damage the skin and heel horn
• D. nodosus invades, creates virulence factor-mediated tissue damage
• Cycle of excessive horn growth and erosion follows
• Results in V-shaped cracks in the heel bulbs

• V-shaped erosive cracks in the heel horn (characteristic)
• Mild interdigital skin inflammation
• Usually subclinical or mild lameness
• Predisposes to sole ulcers

• Foot baths (formalin, copper sulfate)
• Topical oxytetracycline spray
• Improve hygiene and housing

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B. NON-INFECTIOUS HOOF LESIONS

4. Laminitis in Cattle

• Metabolic disturbances (rumen acidosis, endotoxemia) release vasoactive substances
• Compromised blood supply to the corium
• Damaged keratinocytes produce abnormal, weakened horn
• Results in: sole hemorrhage, sole ulcers, white line disease, and claw deformities

• Ridges along the hoof wall
• Swelling at the coronary band
• Waxy, flaking solar horn; false soles
• Hemorrhage in the sole (yellow/pink discoloration)
• White line abscesses
• Sole ulcers
• All four feet typically affected to varying degrees

• High-concentrate diets / subacute ruminal acidosis (SARA)
• Transition period (periparturient period)
• Poor flooring (hard concrete)
• Obesity

• Dietary management (buffer feeds, rumen health)
• Corrective hoof trimming (Dutch 5-step method)
• Rubber flooring
• Treat secondary lesions

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5. Sole Ulcer (Rusterholz Ulcer / Pododermatitis Circumscripta)

• P3 (distal phalanx) sinks and rotates, losing its suspensory mechanism (as with laminitis)
• P3 exerts pressure on the corium of the sole over the Rusterholz zone
• Corium is compressed, leading to ischemic necrosis and ulceration

• Moderate to severe lameness, one foot
• Characteristic location: plantar (or palmar) aspect of the outer claw, at the junction of sole and heel
• Defect in the sole horn revealing hemorrhagic or granulomatous corium
• May develop proud flesh (exuberant granulation tissue)
• Outer claw of rear feet most common

• Hoof trimming to relieve pressure from the affected claw
• Wooden/plastic block applied to the sound claw (offloads the ulcerated claw)
• Topical treatment (bandage, antiseptics)
• NSAIDs for pain
• Systemic antibiotics if infected

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6. White Line Disease in Cattle

• Lameness
• White line abscess (black, moist track at the white line) - may be severe
• "Bubble" of granulation tissue bulging from a white line abscess

• Open and drain the abscess; debride necrotic horn
• Apply block to the healthy claw
• Bandage; antibiotic if needed

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7. Toe Ulcer and Toe Necrosis

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8. Thin Soles

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9. Corkscrew Claw (Spiral Claw Deformity)

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10. Hoof Fissures in Cattle

• Axial fissure: Between the two claws, at the abaxial cleft; associated with digital dermatitis
• Horizontal fissure (thimble / hardship groove): Transverse groove or crack parallel to the coronary band; associated with systemic illness, periparturient stress, or laminitis events
• Vertical fissure (sandcrack in cattle): Vertical crack from coronary band downward; often associated with trauma or chronic laminitis

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11. Interdigital Hyperplasia (Fibroma / Corn / Tyloma)

• Chronic irritation of the interdigital skin
• Associated with poor hygiene, other infectious hoof lesions (foot rot, digital dermatitis)
• Strain on interdigital ligaments from poor trimming, abnormal conformation, or unstable surfaces
• Considered multifactorial

• Firm, fibrous mass protruding between the claws
• May become traumatized and secondarily infected
• Variable lameness (often mild without secondary infection)

• Small masses: conservative management, improve hygiene
• Large/infected masses: surgical excision under local anesthesia; systemic antibiotics post-operatively

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12. Deep Digital Sepsis in Cattle

• Sequela to untreated or inadequately treated foot rot, sole ulcers, or white line disease
• Inflammatory necrosis reaches the joint space and tendons
• Once the joint is involved, systemic antibiotics alone are ineffective

• Non-weight bearing lameness; unresponsive to antibiotics
• Draining sinus at the coronet or heel
• Severely swollen fetlock/pastern region

• Digit amputation (salvage procedure) is often required
• Joint lavage + parenteral antibiotics + regional intravenous antibiotic perfusion (RIAP)
• Prognosis: guarded to poor for return to full production

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SECTION III: GENERAL PRINCIPLES OF HOOF MANAGEMENT AND PREVENTION

Hoof Care and Preventive Measures

Nutritional Support for Hoof Health

• Biotin: Most evidence-based supplement for hoof horn quality (horses and cattle)
• Methionine and zinc: Structural components of keratin
• Omega-3 fatty acids: Anti-inflammatory; support corium health
• Vitamin E and selenium: Antioxidant support

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Summary Table: Major Hoof Affections at a Glance

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• Merck/MSD Veterinary Manual: Lameness Originating in the Hoof in Cattle (Updated July 2025)
• Merck/MSD Veterinary Manual: Disorders of the Foot in Horses
• Cornell University College of Veterinary Medicine: Foot Health - NYSCHAP