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Tulathromycin and Diclazuril Lack Efficacy against Theileria haneyi, but Tulathromycin Is Not Associated with Adverse Clinical Effects in Six Treated Adult Horses

Authors :
Cynthia K. Onzere
Morgan Hulbert
Kelly P. Sears
Laura B. A. Williams
Lindsay M. Fry
Source :
Pathogens, Vol 12, Iss 3, p 453 (2023)
Publication Year :
2023
Publisher :
MDPI AG, 2023.

Abstract

Equine theileriosis, caused by Theileria haneyi and Theileria equi, leads to anemia, exercise intolerance, and occasionally, death. Theileriosis-free countries prohibit the importation of infected horses, resulting in significant costs for the equine industry. Imidocarb dipropionate is the only treatment for T. equi in the United States, but lacks efficacy against T. haneyi. The goal of this study was to assess the in vivo efficacy of tulathromycin and diclazuril against T. haneyi. Fourteen T. haneyi-infected horses were utilized. Six were treated with eight weekly 2.5 mg/kg doses of tulathromycin. Three were treated daily for eight weeks with 2.5 mg/kg diclazuril. Three were pre-treated with 0.5 mg/kg diclazuril daily for one month to determine whether low-dose diclazuril prevents infection. Following infection, the dose was increased to 2.5 mg/kg for eight weeks. Two infected horses remained untreated as controls. The horses were assessed via nested PCR, physical exams, complete blood counts, serum chemistry panels, and cytology. Tulathromycin and diclazuril failed to clear T. haneyi and the treated and control groups exhibited similar parasitemia and packed cell volume declines. To obtain additional safety data on tulathromycin use in adult horses, necropsy and histopathology were performed on tulathromycin-treated horses. No significant lesions were detected.

Details

Language :
English
ISSN :
20760817
Volume :
12
Issue :
3
Database :
Directory of Open Access Journals
Journal :
Pathogens
Publication Type :
Academic Journal
Accession number :
edsdoj.9e827046b0f430eb2aba1d90e522c08
Document Type :
article
Full Text :
https://doi.org/10.3390/pathogens12030453