Effect of sodium bisulfate on skin and hooves of horses

Objective-To evaluate the safety of sodium bisulfate for use in horse barn environments by determining its irritant effect on skin and hooves. Animals-6 female mixed-breed ponies. Procedure-Sodium bisulfate was applied to clipped intact skin of 6 ponies t o evaluate its irritant effect after single (48 hours) and repetitive (6 h/ d for 10 days) applications; similar areas of skin were used as untreated c ontrol sites. In addition, sodium bisulfate was applied to the sole of both front hooves of each pony and covered with wet gauze, and the entire hoof was covered with adhesive tape for 48 hours. Results-Contact with moistened sodium bisulfate for 48 hours had no effect on pony skin. Contact with sodium bisulfate for 6 hours on 10 consecutive d ays did not cause gross changes but did cause mild to moderate microscopic changes including epidermal necrosis, hyperkeratosis, capillary congestion, edema, and diffuse mixed inflammatory cell infiltrate. All changes were li mited to the epidermis and superficial dermis. Gross changes in hoof sole, signs of lameness, and increase in digital pulse pressure or pulse intensit y were not detected. Conclusions and Clinical Relevance-Duration of contact with sodium bisulfat e in this study was in excess of that expected under typical husbandry cond itions. Despite this fact, gross changes in skin and hooves were not detect ed. Microscopic lesions were confined to the epidermis and superficial derm is. Results suggest that contact with sodium bisulfate under these conditio ns is safe.