Evaluation of residual antibacterial effects on canine skin surface and hair following treatment with five commercial mousse products against Staphylococcus pseudintermedius.

BACKGROUND Antibacterial effect studies of commercial antiseptics typically have evaluated hair and not the skin. OBJECTIVES To evaluate the antibacterial effects of mousse products on both canine skin and hair. ANIMALS Fifteen short-haired and eight long-haired dogs without skin disease. MATERIALS AND METHODS Five mousses were applied once: (1) 2% chlorhexidine and 2% miconazole; (2) 0.05% phytosphingosine; (3) 2% salicylic acid and 10% ethyl lactate; (4) 3% chlorhexidine and 0.5% climbazole; and (5) 2% chlorhexidine and 1% ketoconazole. Skin swabs and hair were collected from application sites before treatment, and at 1 h and at Day (D)2, D4, D8, D10 and D14 post-treatment. Skin swabs and hair were placed on Mueller-Hinton plates inoculated with Staphylococcus pseudintermedius inoculum suspension. Inhibition zones were measured after incubation. RESULTS Inhibition was not noted with mousses 2 and 3. In mousse 5, inhibition zone sizes produced by swabs from long- and short-haired dogs were not significantly different (p = 0.105), and all swabs and hair produced inhibition until D14, regardless of hair length. By contrast, in mousse 1, inhibition zones produced by swabs from long-haired dogs were smaller than those from short-haired dogs (p < 0.001), and swabs from long-haired dogs produced a shorter duration of bacterial inhibition than hair. CONCLUSIONS AND CLINICAL RELEVANCE The antibacterial effects of mousse 5 were not affected by hair length. Hair may be acceptable for evaluating effects on the skin in short-haired dogs. However, long hair may interfere with product distribution and duration of bacterial inhibition. Therefore, the evaluation of hair alone may overestimate clinically relevant antibacterial effects.