Karen L. Cherrone KLC Veterinary Surgical Services, New York, NY, USA The pinna directs sound toward the middle ear. The size and shape of the auricular cartilage (scapha) determines if the pinna is erect or hanging. The lateral surface is convex, and the medial surface (conchal cavity) is concave. The cartilage contains many foramina where blood vessels and nerves enter. Within the concave surface, there is a protuberance (anthelix) that separates the concha from the more distally located and flat scapha. The basal portion of the concha twists as it rolls to form a tube. A separate cartilaginous band, the annular cartilage, fits within the base of this tube. Opposite the anthelix is a cartilage plate called the tragus, delineated by the lateral margin of the opening of the ear canal. Caudal to this, delineating the caudal margin of the ear canal, is the antitragus. There is a gradual decrease in the amount of hair from the apex to the base of the pinna. The external carotid artery branches into the caudal auricular artery, which forms the lateral, intermediate, and medial vascular rami on the convex surface of the pinna. Branches of these vessels enter the foramina of the pinna and supply the concave surface. Sensory innervation is supplied by the second cervical nerve (convex surface) and the auriculotemporal branches of the trigeminal nerve (concave surface).1 The most common indications for pinnectomy are trauma, lacerations, and neoplasia. Cosmetic forms of pinnectomy (e.g., ear‐cropping) are not supported by the author or editor and will not be discussed in this chapter. Acute, minor fresh wounds to the pinna (<6 hours since injury) may be able to be copiously lavaged and primarily repaired. Chronic, minor wounds should have any infection managed first prior to consideration of delayed primary closure. If the wounds or lacerations are severe, subtotal or total pinnectomy may be indicated.1 Any neoplasia that occurs on the skin may occur on the pinna. Actinic lesions are caused by ultraviolet B light (UBV). They begin as erythematous areas and progress to crusts and plaques over time. These lesions are considered pre‐malignant but may develop into carcinoma in situ if left untreated. White cats and poorly pigmented dog breeds (e.g., Dalmatians and Bull Terriers) are at greater risk of these lesions. Avoidance of the sun and sunscreen are recommended to reduce the risk of developing these lesions and other forms of dermal neoplasia.1,2 Squamous cell carcinoma (SCC) of the pinna occurs most commonly in white‐coated, older cats causing an erosive, painful lesion that is invasive into the auricular cartilage. Metastasis is uncommon. When they do metastasize, it is usually to the lungs and regional lymph nodes. Tumors may also be noted on the eyelids and nares. Diagnosis may be obtained via fine needle aspirate or incisional biopsy.1 Hemangioma and hemangiosarcoma of the pinna are considered UVB‐induced. They are most common in white or light‐colored cats and rare in dogs. Hemangiomas are generally small, raised, blue, or purple‐tinged lesions. Hemangiosarcomas tend to be large, ulcerated, invasive, and painful.1 Basal cell carcinomas
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Pinnectomy
Anatomy
Indications for Pinnectomy
Trauma and Lacerations
Neoplasia
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