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

Abstract

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. Vaccination is highly recommended, and for some activities it is a mandatory requirement of the relevant authority. As there is a dearth of information relating to the impact of concurrent vaccination on the antibody response to EHV and EIV vaccines, they are usually administered separately, often 2 weeks apart. In a previous study of booster vaccination in Thoroughbred racehorses, concurrent vaccination with whole-virus inactivated carbopoladjuvanted EHV and EIV vaccines did not impact negatively on the antibody response. In this study, investigations were extended to concurrent versus separate primary vaccination of warmblood foals. A field study was conducted to compare the immune response to a carbopol-adjuvanted EHV vaccine and an immune stimulating complex (ISCOM)-adjuvanted EI vaccine administered concurrently and 2 weeks apart. No adverse clinical reactions were observed, the pattern of EI and EHV antibody response was similar for both groups, and there was no evidence that concurrent primary vaccination compromised the humoral response. The results are of relevance to horse owners who wish to decrease veterinary costs, limit handling of young animals, and simplify record keeping by vaccinating concurrently.

Evaluation of concurrent vaccinations with recombinant canarypox equine influenza virus and inactivated equine herpesvirus vaccines

“…This result contradicts that of Gildea et al [ 12 ], in which horses immunized with EIV and EHV on the same day had significantly higher antibody levels 2 weeks post-vaccination than those immunized with EIV alone. In addition, our results also contradicted those of Allkofer et al [ 7 ], where the mean antibody titer of separately vaccinated horses was significantly higher than that of concurrently vaccinated horses at 2 weeks post-vaccination. These differences are probably attributable to the types of vaccines and adjuvants, influenza vaccine strains, and variations in horse species in the experiments.…”

“…EHV is an alpha-herpesvirus of the Herpesviridae family that induces symptoms of upper respiratory diseases similar to those induced by EI; however, it also causes abortion in mares and neurological disorders, such as EHV myeloencephalopathy, in foals [ 6 ]. These viruses spread quickly, especially in naïve populations, leading to the implementation of movement restrictions for horses and disruption of equestrian events [ 7 ]. Additionally, because of their high morbidity, infections with these viruses require strict prevention protocols including disease surveillance, quarantine of affected horses, and regular vaccination programs, which ultimately cause enormous financial losses in the equine industry [ 5 ].…”

“…The concurrent vaccination means that administering different vaccines on the same day, but not combined in the same syringe. It not only decreases veterinary expenses but also reduces the stressful environment for foals by limiting handling and restraint [ 7 ]. Nevertheless, according to previous studies, the efficacy of concurrent administration of EIV and EHV vaccines in horses remains controversial.…”

Equine Influenza Virus: An Old Known Enemy in the Americas

“…A booster must be applied six months after the initial vaccination program. This booster provides protection for 12 months [ 96 , 97 ]. However, it has been reported that annual booster vaccination should not be relied on as the sole preventative measure against EIV, and increasing the frequency of booster vaccinations may be beneficial, particularly in young horses in places with high EIV transmission [ 88 ].…”

Inherent Serum Inhibition of Influenza Virus Neuraminidases

“…Influenza viruses are of international importance due to the widespread infection in different livestock, leading to vaccination being utilized across the veterinary field ( 2 ). Equine influenza viruses are important horse pathogens with policies in place that require horses be vaccinated for equine influenza viruses before participation in events or importation ( 3 , 4 ). Furthermore, due to the transmission of influenza viruses from horses to dogs, as well as the endemic infection of influenza viruses in the canine population, canine vaccination is also recommended for dogs with high risk of exposure ( 5 , 6 ).…”