Colloidal Iron Oxide Formulation for Equine Hoof Disinfection

• Main Authors: Maurizio Isola, Cristina Piccinotti, Massimiliano Magro, Luca Fasolato, Fabio Vianello, Maria Luisa Menandro, Parastoo Memarian, Melissa Rossi, Maria Elena Falomo
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Animals
• Subjects: chlorhexidine; povidone-iodine; hoof; horse; pre-surgical disinfection
• Online Access: https://www.mdpi.com/2076-2615/11/3/766

The presence of bacteria of various origins on horse hoofs enables the onset of infections following trauma or even post-surgical wounds. Thus, the analysis of new antibacterial substances is of fundamental importance. In this study, the antibacterial efficacy of Iron Animals (IA), a stable colloidal suspension of iron oxide, organic acids, and detergents, was tested <i>in vitro</i> and <i>in vivo</i>. <i>In vitro</i> assays were performed to test the unspecific inhibitory effect of IA on both gram-positive and gram-negative bacteria monitoring the microorganism growth by spectrophotometry (optical density OD600) at 37 °C for 24 h. <i>In vivo</i> test consists on the quantification of the bacterial load in colony forming units per gram (CFU/g) of specimens collected from the frog region of the anterior hooves of 11 horses. Sampling followed the application of four disinfectant protocols consisting of two consecutive 3 min scrubs with 50 mL of 10% Povidone-iodine (PI) or 4% Chlorhexidine (CHx), with or without an additional application for 15 min of 10 mL of Iron Animals (PI+IA and CHx+IA). <i>In vitro</i>, IA completely suppressed the bacterial growth of all the tested microorganisms, resulting in effectiveness also against CHx-resistant bacteria, such as <i>Staphylococcus aureus</i>. In vivo, PI emerged as an ineffective protocol; CHx was effective in 18% of cases, but with the addition of IA (CHx + IA) its use emerged as the best disinfectant protocol for horse hoof, achieving the lowest bacterial load in 55% of cases. The addition of IA, after PI or CHx, improves the effectiveness of both disinfectants leading to the highest bactericidal activity in 82% of cases.