Concurrent development of generalised demodicosis, dermatophytosis and meticillin‐resistant Staphylococcus pseudintermedius secondary to inappropriate treatment of atopic dermatitis in an adult dog

A four-year-old female spayed mongrel dog was presented in May 2015 with a two-year history of poorly controlled atopic dermatitis (AD) and increased pruritus over the last few months. Current medications included Apoquel, prednisone, diphenhydramine and cephalexin. A deep skin scrape revealed Demodex canis and Demodex cornei and superficial cytology revealed coccoid bacteria. Aerobic skin culture revealed meticillin-resistant Staphylococcus pseudintermedius (MRSP) and dermatophyte culture grew Microsporum canis . Therapy included discontinuation and taper of immunosuppressive medications, oral enrofloxacin and ivermectin and Malaseb shampoo. Complete resolution of demodicosis, dermatophytosis and MRSP was accomplished in four months. Long-term control of AD was established by using low-dose prednisone therapy with no relapse in infectious disease. This case illustrates the risk of development of multiple infectious diseases secondary to immunosuppression with multimodal drug therapy for treatment of AD, and it exemplifies the importance of performing in-house diagnostic testing.