Epidemiology and reproductive outcomes of EHV‐1 abortion epizootics in unvaccinated Thoroughbred mares in South Africa

Abstract

Ethical animal researchThis was a retrospective study performed on data collected from privately owned animals that received the highest standards of care. All activities were conducted with informed owners. 2 Conflict of interestThere are no conflicts of interest. Source of fundingThe Equine Research Centre of the University of Pretoria funded the study. AcknowledgementsThe authors gratefully acknowledge the cooperation and generous assistance of the owners and staff of Moutonshoek and Summerhill. Conclusions:The marked difference in morbidity between the two epizootics may be associated with routes of introduction or intervention strategy dictated by availability of molecular diagnostic techniques. Unexpectedly, EHV-1 was not more commonly associated with post-abortion complications.

Genetic diversity of equine herpesvirus 1 isolated from neurological, abortigenic and respiratory disease outbreaks

“…Respiratory infections are common, and the virus can also cause multiple abortion outbreaks, neonatal death and neurological damage that may lead to fatal paralysis (Goehring, Landolt, & Morley, 2010; Irwin et al., 2007; Mumford et al., 1987; Schulman, Becker, van der Merwe, Guthrie, & Stout, 2014). After initial infection of the upper respiratory tract epithelium, a highly cell‐associated viraemia develops (Gibson, Slater, & Field, 1992; Scott, Dutta, & Myrup, 1983).…”

Report of the Fourth International Havemeyer Workshop on Equid Herpesviruses (EHV) EHV‐1, EHV‐2 and EHV‐5

“…In South Africa, herpesvirus abortion outbreaks were described in unvaccinated pregnant mares on two very large stud farms [6]. Successful control of the outbreaks depended on early detection using quantitative PCR, application of D.I.S.H.…”

“…(Disinfect, Isolate, Sample, Hygiene), and vaccination of pregnant broodmares. The sub-division of broodmares into even smaller groups within sight and sound of the original group members probably minimises separation stress [6]. EHV-1 can remain stable in water and sediment for up to 3 weeks under experimental conditions [7].…”

Equine herpesvirus‐1: Dealing practically but effectively with an ever present threat

“…In mares in late pregnancy, transport, relocation, social group change and other forms of stress may increase the risk of latently infected horses starting nasal shedding of EHV-1 as well as the virus crossing the placenta in the pregnant uterus, resulting in fetal infection and abortion [5]. As recommended in the HBLB Codes of Practice and by Schulman et al [3] pregnant mares with similar foaling dates should be maintained in small groups from as early in their pregnancies as possible without transportation and re-mixing until they have successfully foaled. Pregnant mares, that arrive following transportation and social disruption, such as those bought from sales or attending veterinary clinics, should always be considered as being 'high risk' for EHV abortion and should be managed accordingly with particular due diligence to the potential risk they pose.…”