Chapter 122 Pinna and External Ear Canal

Question 1

What is the major blood supply to the middle ear

Answer 1

Tympanic artery (derived from the maxillary artery and enters through small foramen caudal to the TMJ)

Question 2

What is the major blood supply to the convex surface of the pinna and its branches

Answer 2

Caudal auricular artery branches off the external carotid artery and forms lateral, intermediate, and medial vascular rami on the convex surface of the pinna

Question 3

Where are the carotids in relation to the bulla

Answer 3

External carotid is ventral to the bulla
Internal carotid is medial to the bulla

Question 4

Whats the most common bacteria in canine otitis media

Answer 4

70% of ears cultured in one study had S. pseudintermedius
others - Pseudomonas spp. and Malassezia yeast

Question 5

Most commonly diagnosed tumor of the ear and what breed is overrepresented

Answer 5

Ceruminous gland adenocarcinoma – Most commonly diagnosed aural tumor in dogs and cats
Cocker spaniels overrepresented – 16% of patients with ceruminous gland adenocarcinoma and 39% of ceruminous gland adenoma

Question 6

What percentage of aural tumors are malignant in cats vs dogs

Answer 6

87.5% of aural tumors in cats are malignant
60% in dogs are malignant