A Scoping Review of Non-Structural Airway Disease as a Cause of Poor Performance in Racehorses.

The association between poor performance and respiratory disease in Thoroughbred racehorses that do not have a structural abnormality of the respiratory tract, is often based on anecdotal evidence. The objective of this scoping review was to examine the scientific evidence for such associations. Publications were selected based on a search of three databases (PubMed, Scopus, and CAB Direct), in English and without date restriction, followed by a screening process to exclude non-relevant papers, duplicates, and reviews.

Primary vaccination in foals: a comparison of the serological response to equine influenza and equine herpesvirus vaccines administered concurrently or 2 weeks apart.

This study compared concurrent and separate primary vaccination against equid alphaherpesviruses 1 and 4, genus Varicellovirus, subfamily Alphaherpesvirinae, family Herpesviridae, and equine influenza A virus, genus Alphainfluenzavirus, family Orthomyxoviridae. Their vernacular names are equine herpesvirus 1 and 4 (EHV1/4) and equine influenza virus (EIV). Infection with these respiratory pathogens is associated with loss of performance, interruption of training schedules, and on occasion, cancellation of equestrian events.

Evaluation of Current Equine Influenza Vaccination Protocols Prior to Shipment, Guided by OIE Standards.

To facilitate the temporary importation of horses for competition and racing purposes, with a minimum risk of transmitting equine influenza, the World Organisation for Animal Health (Office International des Epizooties, or OIE), formally engaged in a public-private partnership with the Federation Equestre Internationale (FEI) and the International Federation for Horseracing Authorities (IFHA) to establish, within the context of existing OIE standards, a science-based rationale to identify the ideal time period for equine influenza vaccination prior to shipment. Field trials using vaccines based on different technologies were carried out on three continents. The antibody response post-booster vaccination at intervals aligned with the different rules/recommendations of the OIE, FEI, and IFHA, was monitored by single radial haemolysis.

Annual booster vaccination and the risk of equine influenza to Thoroughbred racehorses.

Background: Equine influenza (EI) outbreaks occurred among horses on four racing yards (two National Hunt, one Flat, one mixed National Hunt racing/breeding yard) in Ireland within a 4-week period.

Objectives: To carry out a detailed analysis of racing yards affected in order to identify the source of infection and monitor virus spread among a vaccinated population.

Study Design: Observational field study.

Equine Rhinitis A Virus Infection in Thoroughbred Racehorses-A Putative Role in Poor Performance?

The aim of this study was to identify respiratory viruses circulating amongst elite racehorses in a training yard by serological testing of serial samples and to determine their impact on health status and ability to race. A six-month longitudinal study was conducted in 30 Thoroughbred racehorses (21 two-year-olds, five three-year-olds and four four-year-olds) during the Flat racing season. Sera were tested for the presence of antibodies against equine herpesvirus 1 and 4 (EHV-1 and EHV-4) and equine rhinitis viruses A and B (ERAV and ERBV) by complement fixation (CF) and equine arteritis virus (EAV) by ELISA.

The First Detection of Equine Coronavirus in Adult Horses and Foals in Ireland.

The objective of this study was to investigate the presence of equine coronavirus (ECoV) in clinical samples submitted to a diagnostic laboratory in Ireland. A total of 424 clinical samples were examined from equids with enteric disease in 24 Irish counties between 2011 and 2015. A real-time reverse transcription polymerase chain reaction was used to detect ECoV RNA.

Whole Genome Sequencing of the First H3N8 Equine Influenza Virus Identified in Malaysia.

In August 2015, Malaysia experienced an outbreak of acute respiratory disease in racehorses. Clinical signs observed were consistent with equine influenza (EI) infection. The index cases were horses recently imported from New Zealand.

Molecular Characterisation of Equine Herpesvirus 1 Isolates from Cases of Abortion, Respiratory and Neurological Disease in Ireland between 1990 and 2017.

Multiple locus typing based on sequencing heterologous regions in 26 open reading frames (ORFs) of equine herpesvirus 1 (EHV-1) strains Ab4 and V592 was used to characterise 272 EHV-1 isolates from 238 outbreaks of abortion, respiratory or neurological disease over a 28-year period. The analysis grouped the 272 viruses into at least 10 of the 13 unique long region (U) clades previously recognised. Viruses from the same outbreak had identical multi-locus profiles.

Multifocal Equine Influenza Outbreak with Vaccination Breakdown in Thoroughbred Racehorses.

Equine influenza (EI) outbreaks occurred on 19 premises in Ireland during 2014. Disease affected thoroughbred (TB) and non-TB horses/ponies on a variety of premises including four racing yards. Initial clinical signs presented on 16 premises within a two-month period.

Equid herpesvirus 8: Complete genome sequence and association with abortion in mares.

Equid herpesvirus 8 (EHV-8), formerly known as asinine herpesvirus 3, is an alphaherpesvirus that is closely related to equid herpesviruses 1 and 9 (EHV-1 and EHV-9). The pathogenesis of EHV-8 is relatively little studied and to date has only been associated with respiratory disease in donkeys in Australia and horses in China. A single EHV-8 genome sequence has been generated for strain Wh in China, but is apparently incomplete and contains frameshifts in two genes.

Molecular characterisation of equine group A rotaviruses in Ireland (2011-2015).

The molecular epidemiology of equine group A rotaviruses (RVAs) in Ireland from 2011 to 2015 was investigated. Of 438 diagnostic specimens submitted from foals with enteric disease, 102 (23.3%) were positive for RVA using an immunochromatographic assay.

Genetic typing of bovine viral diarrhoea virus in cattle on Irish farms.

The aim was to carry out a phylogenetic study of bovine viral diarrhoea viruses (BVDV) circulating in Irish cattle herds from 2011 to 2014. Three hundred and twenty five viruses from 267 herds were subtyped by nucleotide sequence analysis of the 5'UTR and/or the N regions. All viruses investigated in this study belonged to species BVDV-1 with BVDV-1a as the prominent subtype (97%).

Concurrent vaccination against equine influenza and equine herpesvirus - a practical approach.

Background: There is a lack of information concerning concurrent administration of vaccines against equine influenza virus (EIV) and equine herpesvirus 1 and 4 (EHV-1/4).

Objectives: The primary objective of this study was to determine the impact of the concurrent use of EIV and EHV-1/4 vaccines in Thoroughbred racehorses on their humoral immune response to EIV.

Methods: This study was carried out on a population of 30 horses using an inactivated whole-virus EIV vaccine and an inactivated EHV-1/4 vaccine.

Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012.

Background: In 2012, equine influenza (EI) virus was confirmed as the cause of outbreaks of respiratory disease in horses throughout South America. In Uruguay and Argentina, hundreds of vaccinated thoroughbred horses in training and racing facilities were clinically affected.

Objective: To characterise the EI viruses detected during the outbreak in Uruguay and Argentina.

The impact of different equine influenza vaccine products and other factors on equine influenza antibody levels in Thoroughbred racehorses.

Reasons For Performing Study: More knowledge of equine influenza (EI) vaccine usage in training yards and the factors that influence serological response to vaccination are required to determine evidence-based vaccination strategies.

Objectives: The aim of this study was to ascertain the vaccination history of a population of Thoroughbred racehorses and identify factors that impacted on their antibody titres against EI.

Study Design: Observational field study.

The evaluation of three diagnostic tests for the detection of equine influenza nucleoprotein in nasal swabs.

Background: Equine influenza (EI) is a highly contagious respiratory disease of horses.

Objectives: The aim of this study was to evaluate two rapid antigen detection kits (Directigen or DFA, and Espline) and a commercial ELISA for the detection of EI nucleoprotein in nasal swabs.

Method: Nasal swab samples from naturally and experimentally infected horses were used to compare the sensitivity and specificity of these assays to virus isolation (VI) and real-time RT-PCR.

The evaluation of a nucleoprotein ELISA for the detection of equine influenza antibodies and the differentiation of infected from vaccinated horses (DIVA).

Background: Antibodies against equine influenza virus (EIV) are traditionally quantified by haemagglutination inhibition (HI) or single radial haemolysis (SRH).

Objectives: To evaluate an ELISA for the detection of antibodies against influenza nucleoprotein in the diagnosis and surveillance of equine influenza (EI).

Methods: The ELISA was compared with the SRH and HI tests.

Epidemiological and virological investigations of equine influenza outbreaks in Ireland (2010-2012).

Background: Outbreaks of equine influenza (EI) in endemic populations cause disruption and economic loss.

Objectives: To identify (i) factors involved in the spread of EI (ii) virus strains responsible for outbreaks (iii) single radial haemolysis (SRH) antibody levels correlating with protection against current virus strains (iv) evidence of vaccination breakdown.

Methods: RT-PCR, virus isolation and SRH were carried out on nasopharyngeal swabs and blood samples collected from horses, ponies and donkeys on affected premises.

Comparison of primary vaccination regimes for equine influenza: working towards an evidence-based regime.

Reasons For Performing Study: Vaccination is crucial to the control of equine influenza (EI). The study was conducted in an effort to lay the groundwork for achieving international harmonisation of regulatory requirements based on scientific evidence of performance of different vaccination regimes.

Objectives: To evaluate the effectiveness of 3 different primary vaccination regimes: vaccination with the minimal intervals permitted by the racing authorities; vaccination in accordance with the manufacturer's instructions and vaccination with the longest intervals permitted by the racing authorities.

Humoral response and antiviral cytokine expression following vaccination of thoroughbred weanlings--a blinded comparison of commercially available vaccines.

Previous studies in experimental ponies using interferon gamma (IFN-γ) as a marker for cell mediated immune (CMI) response demonstrated an increase in IFN-γ gene expression following vaccination with an ISCOM subunit, a canarypox recombinant and more recently, an inactivated whole virus vaccine. The objective of this study was to carry out an independent comparison of both humoral antibody and CMI responses elicited following vaccination with all these vaccine presentation systems. Antibody response of 44 Thoroughbred weanlings was monitored for three weeks following the second dose of primary vaccination (V2) by single radial haemolysis (SRH).

Equine influenza--a global perspective.

To date, equine influenza outbreaks have been reported all over the world with the exception of a small number of island nations including New Zealand and Iceland. Influenza is endemic in Europe and North America and is considered to be of potentially major economic significance to the equine industry worldwide. The importation of subclinically infected vaccinated horses, and inadequate quarantine procedures have resulted in several major outbreaks in susceptible populations for example, in Australia (2007) when more than 76,000 horses on over 10,000 properties were reported as infected.

A comparison of antibody responses to commercial equine influenza vaccines following primary vaccination of Thoroughbred weanlings--a randomised blind study.

Many racing authorities, sales companies and equestrian bodies have mandatory vaccination policies for equine influenza (EI). The consequences of lack of vaccine efficacy include clinical disease, disruption to training programmes, the cancellation of equestrian events and the introduction of virus to susceptible populations. The correlation between antibody against the virus haemagglutinin and protection against influenza has been well established.

The molecular epidemiology of equine influenza in Ireland from 2007-2010 and its international significance.

Reasons For Performing The Study: Antigenic and genetic drift of equine influenza (EI) virus is monitored annually by the Expert Surveillance Panel (ESP), which make recommendations on the need to update vaccines. Surveillance programmes are essential for this process to operate effectively and to decrease the risk of disease spread through the international movement of subclinically infected vaccinated horses. Not only is surveillance necessary to inform vaccine companies which strains are in circulation, but it serves as an early warning system for horse owners, trainers and veterinary clinicians, facilitating the implementation of appropriate prophylactic and control measures.

Management and environmental factors involved in equine influenza outbreaks in Ireland 2007-2010.

Reasons For Performing Study: Outbreaks of equine influenza (EI) in endemic populations continue to cause economic loss despite widespread vaccination.

Hypothesis: To identify the key management and environmental factors that determine the risk of horses contracting EI in an endemic country and to identify control strategies.

Methods: Real time-polymerase chain reaction (RT-PCR), virus isolation and haemagglutination inhibition were carried out on nasopharyngeal swabs and clotted blood samples collected from horses and ponies showing signs of respiratory disease.

A comparison of antibody responses to commercial equine influenza vaccines following annual booster vaccination of National Hunt horses - a randomised blind study.

Protection against equine influenza virus (EIV) relies largely on the production of circulating antibodies specific for the haemagglutinin (HA) glycoprotein. The objective of this study was to determine the antibody response of National Hunt horses in training to booster vaccination. The antibody response to the six equine influenza vaccines available in Ireland (three whole inactivated vaccines, two subunit vaccines and a canary pox recombinant vaccine), was monitored by single radial haemolysis (SRH) for six months post vaccination.