This three-year-old horse is presented for evaluation of these non-pruritic, non-painful face lesions. Several other young horses in the herd are also affected, and many of these horses also have lesions in the girth area. Which one of the following diagnostic tests would be most likely to identify the cause of the lesions?


a. Bacterial isolation from affected area
b. Determination of serum antibody response to Stephanofilaria stilesi
c. Fungal culture of hair and skin scales
d. Testing for antinuclear antibodies in serum Biopsy