Pinna (Ear Flap)
The external cartilaginous projection of the ear that captures and funnels sound waves into the ear canal.
💬 In Plain English
The pinna (plural: pinnae) is the visible outer ear flap of your dog or cat. Composed of a thin framework of elastic cartilage covered on both sides by skin and fur, the pinna is controlled by more than a dozen tiny muscles that allow pets to rotate, tilt, and perk their ears independently to pinpoint sounds. Because the skin is tightly bound to cartilage with fragile blood vessels sandwiched between, vigorous head shaking from ear infections or allergies can rupture these vessels, causing blood to pool inside the flap and inflate it like a puffy pillow (an aural hematoma).
🔬 Clinical & Technical Depth
For Vets & TechniciansFormal Clinical Definition
External cartilaginous projection composed of auricular cartilage enveloped by integument, designed for acoustic funneling, impedance matching, and thermoregulation.
Why Veterinarians Use It
Veterinarians inspect the pinnae for signs of allergic erythema, mite crusts, vasculitis, alopecia, and aural hematomas.
Clinical Context Encountered
Examined during routine ear checks or when treating dogs with swollen "pillow" ear flaps.
Clinical Reference Guide (Anatomical Structure)
Anatomical Location
Paired dorsolateral structures of the cranial vault attached to the auricular cartilage of the external ear canal.
Normal Physiological Function
Collects and focuses acoustic waves into the vertical auditory canal; assists in non-verbal canine/feline body language communication.
🐕 vs 🐈 Species Differences
Dogs exhibit tremendous conformational variation from erect prick ears to heavy pendulous drop ears (which trap moisture and yeast); cats almost uniformly maintain erect triangular pinnae.
- •A balloon-like fluid swelling of the ear flap (aural hematoma) requires prompt veterinary care: left untreated, the clot contracts into a permanently disfigured "cauliflower ear."
❓ Questions to Ask Your Veterinarian
Take these actionable questions with you to your next clinic visit or appointment:
- 1If an aural hematoma is present, should it be drained or surgically repaired with mattress sutures?
- 2Has the underlying ear canal infection (otitis externa) triggering the head shaking been treated?
- 3Are the crusts on the pinna margin caused by Sarcoptes mites or fly strike?
Academic & Clinical References
- Diseases of the Pinna in Dogs and CatsOrganization: Merck Veterinary Manual • Accessed: 2026-01-10https://www.merckvetmanual.com