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Journal of parasitology research2025; 2025; 8948099; doi: 10.1155/japr/8948099

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 p C. bovis mites, and it can be considered an alternative therapeutic option in horses.
Copyright © 2025 Juan D. Carbonell et al. Journal of Parasitology Research published by John Wiley & Sons Ltd.
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Publication Date: 2025-04-22 PubMed ID: 40308533PubMed Central: PMC12041626DOI: 10.1155/japr/8948099Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This double-blind randomized trial in 32 Spanish-Breton horses found that adding benzoyl peroxide to a topical pyrethroid markedly reduced Chorioptes bovis mite counts compared with pyrethroid alone, although visible pastern dermatitis lesions improved only modestly. No adverse reactions were observed, and environmental disinfection was included for all groups.

What the study asked and why it matters

  • Question: Does combining benzoyl peroxide (a keratolytic/degreasing agent) with a topical pyrethroid improve outcomes for chorioptic mange in horses compared with a pyrethroid alone?
  • Importance: Chorioptes bovis lives superficially in crusts and hair, making it hard for acaricides to reach; relapses are common, and clinical resolution often lags behind mite kill.
  • Clinical gap: While topical acaricides are recommended, robust comparative data in heavily feathered draft-type horses are limited.

Study design at a glance

  • Population: 32 Spanish-Breton horses naturally infested on the legs with Chorioptes bovis.
  • Design: Double-blinded, randomized, three-arm clinical trial with follow-up to Day (D)70.
  • Groups:
    • Group 1: Topical pyrethroid emulsion alone.
    • Group 2: Topical pyrethroid combined with benzoyl peroxide.
    • Group 3: Control (no active treatment).
  • Treatment schedule: Applications once every 14 days for three treatments.
  • Environmental component: Disinfection implemented to reduce reinfestation pressure.
  • Clinical assessments: Each leg scored for equine pastern dermatitis severity (1 = mild, 2 = exudative, 3 = chronic proliferative) at baseline and D10, D25, D37, D56, D70.
  • Parasitological assessments: Adhesive tape (2 × 6 cm) mite counts on D36, D56, D70.
  • Efficacy metric: Abbott’s formula, calculated as efficacy (%) = 100 × (C − T) / C, with C = mean mite count in controls and T = mean mite count in a treated group.
  • Safety: Monitoring for adverse reactions throughout.

Key results

  • Safety: No adverse reactions were attributable to the treatments.
  • Clinical signs: Lesions showed limited improvement across groups despite treatment and mite reduction.
  • Mite reduction (Abbott’s efficacy):
    • Group 1 (pyrethroid alone): 14.58% (early), 47.62% (mid), 55.77% (D70).
    • Group 2 (pyrethroid + benzoyl peroxide): 85.42% (early), 88.10% (mid), 78.85% (D70).
  • Statistical significance: The reduction in Group 2 was statistically significant versus control on D56 and D70; both treated groups outperformed control overall.
  • Overall interpretation: Adding benzoyl peroxide substantially enhanced mite suppression compared with pyrethroid alone, but this did not translate into marked short-term clinical resolution within 70 days.

Mechanistic rationale for the combination

  • Pyrethroids: Neurotoxic to mites (sodium channel modulators) but may have limited penetration through crusts, scales, and heavy feathering.
  • Benzoyl peroxide: Keratolytic, degreasing, and follicular-flushing; can reduce surface debris and enhance cutaneous penetration of co-applied acaricides.
  • Proposed synergy: By clearing keratin and exudate, benzoyl peroxide likely improves pyrethroid contact with superficial mites, explaining higher efficacy.

Why mite kill did not fully match clinical improvement

  • Lag effect: Inflammatory changes, hyperkeratosis, and crusting may persist after mites are reduced.
  • Secondary factors: Bacterial/yeast overgrowth and self-trauma can sustain dermatitis independent of current mite burden.
  • Anatomic challenges: Dense feathering and pastern conformation can trap moisture and irritants, slowing visible recovery.
  • Re-exposure risk: Even with disinfection, environmental or in-contact sources can maintain low-level mite presence.

Strengths

  • Prospective, double-blind randomization increases internal validity.
  • Natural infestations in a relevant draft-type breed enhance real-world applicability.
  • Objective mite counts plus clinical scoring provide complementary endpoints.
  • Inclusion of environmental disinfection reflects good practice and controls a major confounder.

Limitations

  • Sample size (n = 32 across three arms) may limit power to detect differences in clinical scores.
  • Short-to-moderate follow-up (70 days) may not capture relapse dynamics beyond the study window.
  • Adhesive tape sampling captures a small area and may under- or over-represent whole-limb mite loads.
  • Clinical scoring scale (1–3) is coarse; subtle changes may be missed.
  • Only topical regimens were compared; no head-to-head with other contemporary options.

Clinical implications

  • Therapeutic choice: A pyrethroid plus benzoyl peroxide regimen can meaningfully reduce C. bovis counts and is a reasonable option when pyrethroid alone underperforms.
  • Treatment cadence: Repeated applications at two-week intervals (three total) were well tolerated and effective for mite reduction in this cohort.
  • Expectations: Counsel owners that visible lesion resolution may lag behind mite kill; adjunctive care for secondary infection/inflammation may be needed.
  • Application technique: Thorough cleansing and, when appropriate, careful trimming of feathers/crusts can improve penetration and outcomes.
  • Biosecurity: Disinfect environments and tackle in-contact animals and fomites (bedding, brushes, wraps) to limit reinfestation.
  • Monitoring: Reassess at 4–10 weeks; consider extending or repeating cycles if clinical signs persist despite parasitological improvement.

Future directions

  • Optimize protocols: Define ideal contact times, concentrations, and number of cycles for combination therapy.
  • Broader comparisons: Head-to-head trials against other topical or systemic ectoparasiticides and integrated regimens.
  • Outcome measures: Finer-grained clinical scales, owner-reported outcomes, and quality-of-life metrics.
  • Long-term control: Studies focusing on relapse prevention, environmental management intensity, and seasonality.
  • Resistance and safety: Surveillance for acaricide tolerance and extended safety profiling across breeds and ages.

Bottom line

  • Adding benzoyl peroxide to a topical pyrethroid substantially improved mite reduction (roughly 80–88% mid-study, ~79% by D70) compared with pyrethroid alone (~56% by D70), without added adverse effects. Visible dermatitis improved only modestly over 70 days, so pairing effective mite control with diligent environmental hygiene and lesion-focused supportive care remains essential.

Cite This Article

APA
Carbonell JD, Fernández N, Escobar MJ, Álvarez MT, Sánchez L, Hernández A, Meana A. (2025). Comparative Efficacy of Topical Pyrethroids and Benzoyl Peroxide for Treating Chorioptic Mange in Spanish-Breton Horses. J Parasitol Res, 2025, 8948099. https://doi.org/10.1155/japr/8948099

Publication

Journal of parasitology research
ISSN: 2090-0023
NlmUniqueID: 101526294
Country: United States
Language: English
Volume: 2025
Pages: 8948099
PII: 8948099

Researcher Affiliations

Carbonell, Juan D
  • Department of Animal Health, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.
Fernández, Nélida
  • Faculty of Veterinary, University Alfonso X El Sabio, Madrid, Spain.
Escobar, Manuel J
  • Clinical Horse Veterinarians, Madrid, Spain.
Álvarez, Maria T
  • Clinical Horse Veterinarians, Madrid, Spain.
Sánchez, Lucia
  • Clinical Horse Veterinarians, Madrid, Spain.
Hernández, Aday
  • Clinical Horse Veterinarians, Madrid, Spain.
Meana, Aránzazu
  • Department of Animal Health, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.

Conflict of Interest Statement

The authors declare no conflicts of interest.

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