Veterinary Research Communications

, Volume 32, Issue 1, pp 75–92 | Cite as

Effects of oral tetrachlorvinphos fly control (Equitrol®) administration in horses: Physiological and behavioural findings

  • J. Berger
  • S. Valdez
  • B. Puschner
  • C. M. Leutenegger
  • I. A. Gardner
  • J. E. Madigan
Original Article
First Online:
Received:
Accepted:

Abstract

Highly reactive horses may pose risks to humans involved in equestrian activities. Among the factors that may affect horses’ reactivity to external stimuli are pesticides used for fly control in equine facilities. The organophosphorus (OP) insecticide tetrachlorvinphos (TCVP) is used as a feed-through larvicide to prevent completion of the fly larval life cycle in horse manure. TCVP exerts its effect by inhibiting the enzyme cholinesterase (ChE) leading to the accumulation of the neurotransmitter acetylcholine (AChE) in synapses of the central and peripheral nervous systems. The aim of the present study was to investigate alterations of whole-blood ChE levels associated with feeding a commercially available product (Equitrol, Farnam Companies, Inc.) to horses for fly control. A second aim was to report neurological, physiological and behavioural findings in addition to profiles of selected immune markers (IFN-γ, IL-12p40 and COX-2) and serum thyroid hormones during and after a 30-day treatment period of TCVP feeding. The results indicated significant decreases in whole-blood ChE activity and concomitant behavioural alterations, manifested as increased reactivity and decreased controllability in treated horses. No changes were detected in physiological or neurological parameters, immune markers or thyroid hormones in treated (n = 6) or control (n = 4) horses during the course of the study.

Keywords

TCVP Horse Behaviour Stimulus reactivity Acetylcholinesterase Butyrylcholinesterase 
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Copyright information

© Springer Science + Business Media B.V. 2007

Authors and Affiliations

  • J. Berger
    • 1
    • 7
  • S. Valdez
    • 2
  • B. Puschner
    • 3
  • C. M. Leutenegger
    • 4
  • I. A. Gardner
    • 5
  • J. E. Madigan
    • 6
  1. 1.Behaviour Service, Veterinary Medical Teaching HospitalUniversity of CaliforniaDavisUSA
  2. 2.San Luis Rey Equine HospitalBonsallUSA
  3. 3.California Animal Health and Food Safety LaboratoryUniversity of CaliforniaDavisUSA
  4. 4.IDEXX LaboratoriesWest SacramentoUSA
  5. 5.Department of Medicine and Epidemiology, School of Veterinary MedicineUniversity of CaliforniaDavisUSA
  6. 6.Department of Medicine and Epidemiology, Lucy Whittier Molecular and Diagnostic Core Facility, School of Veterinary MedicineUniversity of CaliforniaDavisUSA
  7. 7.Veterinary Medicine and EpidemiologyUniversity of CaliforniaDavisUSA

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