Comparative Efficacy of Topical Pyrethroids and Benzoyl Peroxide for Treating Chorioptic Mange in Spanish-Breton Horses

Abstract

Chorioptic mange is a challenging condition to treat due to the superficial locations of the nonhematophagous mite Chorioptes bovis, and while topical acaricides are recommended, the clinical feature relapses are frequent. In a double-blinded clinical trial, three randomized groups of Spanish-Breton horses (n = 32) naturally infected with C. bovis on their legs were evaluated over a period of 70 days. All treatments were applied once every 14 days for three treatments. Before treatment and on Day (D)10, D25, D37, D56, and D70, each leg per animal was scored according to equine pastern dermatitis clinical presentations and severity (1 = mild, 2 = exudative, and 3 = chronic proliferative), and mite reduction was calculated using a 2 cm × 6 cm adhesive tape counting total mites on D36, D56, and D70. The trial aimed to assess the clinical improvement and efficacy of a topical pyrethroid emulsion alone (Group 1), and in combination with benzoyl peroxide (Group 2), compared to a control group (Group 3). The trial also included environmental disinfection. The acaricide efficacy was determined using Abbott’s formula. Our analysis reveals no adverse reactions attributable to the treatment, yet lesions showed limited clinical improvement. Both treatment groups exhibited mite reduction compared to the control. The mite reduction on the evaluated days was 14.58%, 47.62%, and 55.77% for Group 1 and 85.42%, 88.10%, and 78.85% for Group 2, respectively. The mite reduction was significant in Group 2 on D56 and D70 (p < 0.0156) compared to the pretreatment and superior to Group 1 (p < 0.0229) at the end of the study (D70). The age and mite numbers showed no significant connection. In horses with higher clinical scores, there were no significant changes, most probably due to the short length of the study. The combination of benzoyl peroxide with topical pyrethroids can reduce the numbers of C. bovis mites, and it can be considered an alternative therapeutic option in horses.