Fifteen percent to 20% of feedlot heifers that recently arrived from several auction markets are anorectic. Physical examination of the heifers shows serous nasal and ocular discharge, short explosive cough, and hyperemia of nasal mucosa. Which of the following is the most likely diagnosis?
a. Atypical interstitial pneumonia
b. Infectious bovine rhinotracheitis
c. Mucosal disease
d. Pasturellosis
e. Mycoplasmosis