Diluted sodium hypochlorite (bleach) in dogs: antiseptic efficacy, local tolerability and in vitro effect on skin barrier function and inflammation.

BackgroundDiluted sodium hypochlorite represents an inexpensive and widely available topical antiseptic, but there are no tolerability and efficacy data in veterinary dermatology. ObjectivesTo determine the in vivo antibacterial effect and tolerability of topical diluted bleach application and to assess its in vitro effect on skin barrier lipids and anti-inflammatory properties on keratinocytes. MethodsTopical hypochlorite at 0.05% and tap water were applied to both sides of the thorax of four healthy dogs. The anti-inflammatory effect on canine keratinocytes was determined by real-time polymerase chain reaction; skin barrier integrity was assessed by evaluating stratum corneum lipid changes in canine stratified epidermal constructs. ResultsThe cell viability of primary keratinocytes treated with water and diluted hypochlorite at 0.005 and 0.01%, reduced the percentage of viable cells by 10%. The exposure of primary keratinocytes to 0.005% diluted hypochlorite significantly reduced the induction of inflammatory genes chemokine ligand-2 (CCL2; P = 0.015) and thymus and activation-regulated chemokine (TARC/CCL17, P = 0.032). There were no changes in skin lipid ceramide and nonceramide fractions in stratified epidermal constructs cultured for 17 days with 0.05% hypochlorite. Topical hypochlorite at 0.05% and tap water were well-tolerated without signs of skin irritation. Although a marked reduction in bacterial counts was seen within 20 min of diluted bleach application compared to the tap water control, this was only marginally significant (P = 0.06). Conclusions and clinical importanceThe results indicate that a topical diluted bleach solution, at either 0.05 or 0.005% hypochlorite concentrations, is a well-tolerated antiseptic that also exhibits anti-inflammatory properties.