Gracie, a 10-year-old spayed cocker spaniel, was presented because she failed to regrow hair five months after surgery to remove a benign skin mass from the left lateral thorax. In the last year, Gracie had also experienced several episodes of superficial pyoderma on her abdomen that was responsive to cephalosporin therapy. The results from the preoperative serum chemistry profile, complete blood count, and urinalysis were within normal limits. The serum T4 concentration was in the low normal range. Hypertension, noted in the health record, was normalized with benazepril treatment. Gracie had a normal appetite, and there were no noticeable changes in thirst or urination. Dermatologic examination revealed a noninflammatory alopecia on the left lateral trunk with clipper marks still sharply visible, as if she were clipped yesterday. A slight scale was present on otherwise healthy skin. There was no pruritus. The ventral abdomen had several large flaccid green pustules 3 to 4 mm across. The results of a skin scraping were negative. Cytology from the pustules revealed large numbers of neutrophils and intracellular and extracellular coccoid bacteria. A trichogram revealed all hairs to be in telogen phase.
What is the most likely cause for Gracie's failure to regrow hair following surgery?
c. Telogen arrest
d. Cyclical flank alopecia