Evaluation of in vitro activity of herbal formula Di Er You and herb Coptis against bacteria isolated from dogs with otitis externa.

ABSTRACT

OBJECTIVE: To determine the in vitro activity of the herbal formula Di Er You (DEY) and the single-herb Coptis against bacteria cultured from dogs with otitis externa. ANIMALS 32 client-owned dogs diagnosed with otitis externa. METHODS: A sample of otic debris from each patient was collected and plated onto a fresh Sheep's Blood Agar plate in the hospital. After bacterial growth was confirmed, 4 wells were created, numbered randomly, and treated with saline (placebo), DEY, Coptis, and Zymox Otic Enzymatic Solution with 1% Hydrocortisone (Zymox). After 24 hours of incubation, the diameter of the zone of inhibition (dZOI) of each treatment was measured and recorded, and compared among treatments. A sample of the bacterial colonies grown was submitted to an outside lab for bacterial identification. RESULTS: The mean ± SD dZOI values for saline, DEY, Coptis, and Zymox treated wells were 0.25 ± 1.41, 12.47 ± 3.92, 14.25 ± 7.12, and 3.22 ± 5.12, respectively. Post hoc multiple comparisons test revealed that (1) saline-treated wells had significantly smaller dZOI values than the other 3 groups (all P < .001), (2) Zymox treated wells had significantly smaller dZOI values than either herbal treated groups (both P < .001), and (3) DEY treated wells had significantly smaller dZOI values than those treated with Coptis (P = .0042). CLINICAL RELEVANCE The results from this in vitro study suggested that both DEY and Coptis could be effective treatments in inhibiting the growth of bacteria in dogs with otitis externa. Prospective randomized controlled clinical trials are warranted to confirm these findings.