A group of 6-10 week old lambs and their dams have crusted, proliferative lesions on the lips. PE shows underlying crusts consisting of raised granulation tissue. There are no lesions on the buccal or lingual mucosa. The majority of the lambs are affected, but only 5% of the adult sheep are affected. Affected lambs are active and are nursing. The only adult goat on the farm has similar lesions. The horses, cattle, and pigs on the farm are unaffected. Which of the following is the most appropriate management?
a. Addition of organic iodine to trace mineralized salt
b. Oral administration of griseofulvin
c. Parenteral administation of oxytetracycline
d. Parenteral administration of procaine penicillin G
e. Observation